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Behavior and Design of Grouted Anchors Loaded in Tension Including Edge and Group Effects and Qualification of Engineere...


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BEHAVIOR AND DESIGN OF GROUT ED ANCHORS LOADED IN TENSION INCLUDING EDGE AND GROUP E FFECTS AND QUALIFICATION OF ENGINEERED GROUT PRODUCTS By JENNIFER LYNN BURTZ A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLOR IDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS OF THE DEGREE OF MASTER OF ENGINEERING UNIVERSITY OF FLORIDA 2003

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ii ACKNOWLEDGMENTS There are many individuals whose aid a nd guidance made this thesis and the accompanying research a success. The author extends the utmost thanks to Dr. Ronald A. Cook. His extensive knowledge and support proved invaluable. The discussions held with Dr. H. R. Hamilton, III were extremely us eful in the development of aspects of the testing program. In addition, the author wish es to thank Dr. John M. Lybas for his help in the completion of this thesis. The author also wishes to thank J ohnny Fung, Brian Simoneau, Chuck Broward, Vanessa Grillo, Kim Lammert, and Brian Korn reich for their assistance, knowledge, and time. Appreciation is also owed to Marcus Ansley from the Florida Department of Transportation for his knowledge and financ ial support and to Walter Hanford from Chemrex for his generous donation of materials. Finally, the author is indebted to her cl ose friends and family. The value of their support cannot be measured.

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iii TABLE OF CONTENTS page ACKNOWLEDGMENTS .................................................................................................. ii TABLE OF CONTENTS................................................................................................... iii LIST OF TABLES............................................................................................................. vi LIST OF FIGURES .......................................................................................................... vii ABSTRACT....................................................................................................................... xi CHAPTER 1. INTRODUCTION .........................................................................................................1 2. BACKGROUND ...........................................................................................................2 2.1 Types of Anchor Systems....................................................................................... 2 2.2 Bonded Anchors...................................................................................................... 3 2.2.1 Adhesive Anchors.......................................................................................... 4 2.2.2 Grouted Anchors............................................................................................ 6 2.3 Previous and Current Studies with Grouted Anchors............................................. 8 3. BEHAVIORAL MODELS..........................................................................................11 3.1 General.................................................................................................................. 11 3.2 Concrete Capacity Design (CCD) Method ........................................................... 11 3.3 Uniform Bond Stress Model................................................................................. 12 4. DEVELOPMENT OF TEST PROGRAM ..................................................................17 4.1 General.................................................................................................................. 17 4.2 Single Grouted Anchor Test Program................................................................... 18 4.3 Group Grouted Anchor Test Program................................................................... 20 5. IMPLEMENTATION OF TEST PROGRAM ............................................................21 5.1 General.................................................................................................................. 21

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iv 5.2 Concrete................................................................................................................ 21 5.3 Specimen Preparation ........................................................................................... 22 5.4 Installation Procedure ........................................................................................... 23 5.5 Apparatus.............................................................................................................. 24 5.6 Loading Procedure................................................................................................ 26 5.7 Data Reduction...................................................................................................... 29 5.7.1 Displacement Calculations for Single Anchor Tests ................................... 29 5.7.2 Displacement Calculations for Group Anchor Tests ................................... 29 6. TEST RESULTS..........................................................................................................31 6.1 General.................................................................................................................. 31 6.2 Single Grouted Anchor Test Results..................................................................... 31 6.3 Group Grouted Anchor Test Results..................................................................... 34 7. TESTED FACTORS INFLUE NCING GROUT BOND STRENGTH.......................36 7.1 General.................................................................................................................. 36 7.2 Strength versus Curing Time ................................................................................ 36 7.3 Threaded Rod versus Deformed Reinforcing Bar ................................................ 37 7.4 Threaded Rod versus Smooth Rod ....................................................................... 37 7.5 Regular Hex Nut versus Heavy Hex Nut.............................................................. 38 7.6 Hole Drilling Technique ....................................................................................... 39 7.7 Damp Hole Installation......................................................................................... 39 7.8 Elevated Temperature........................................................................................... 40 7.9 Summary............................................................................................................... 40 8. DISCUSSION ON DESIGN METHOD FOR GROUTED ANCHORS ....................42 8.1 Current Models ..................................................................................................... 42 8.2 Predicted Model for Grouted Anchor Behavior.................................................... 42 8.3 Proposed Critical Edge Di stance and Critical An chor Spacing Revision............. 43 8.4 Proposed Model for Single Grouted Anchors....................................................... 45 8.5 Proposed Design Model for Grouted Anchor Groups .......................................... 47 9. DISCUSSION ON PROPOSED PRODUCT APPROVAL TESTS ...........................48 9.1 General.................................................................................................................. 48 9.2 Grout/Concrete Bond Stress ( 0)........................................................................... 49 9.3 Test Series to Establish Steel/Grout Bond Stress ( ............................................ 49 9.4 Strength versus Curing Time ................................................................................ 50 9.5 Threaded Rod versus Deformed Reinforcing Bar ................................................ 50 9.6 Hole Drilling Technique ....................................................................................... 51 9.7 Moisture Condition of Hole.................................................................................. 51 9.8 Elevated Temperature........................................................................................... 53 9.9 Horizontal and Overhead Hole Orientation (Optional) ........................................ 53

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v 9.10 Long-term Load (Optional)................................................................................. 55 9.11 Additional Factors............................................................................................... 56 10. SUMMARY, CONCLUSIONS, AND RECOMMENDATIONS...............................57 10.1 Summary............................................................................................................. 57 10.2 Conclusions......................................................................................................... 57 10.3 Recommendations............................................................................................... 59 APPENDIX A NOTATION.................................................................................................................61 B TENSILE LOAD VS. DISPLAC EMENT GRAPHS FOR BASELINE AND HOLE DRILLING TECHNIQUE TEST SERIES..............................................64 C TENSILE LOAD VS. DISPL ACEMENT GRAPHS FOR EDGE DISTANCE TEST SERIES.........................................................................................71 D TENSILE LOAD VS. DISPL ACEMENT GRAPHS FOR GROUP TEST SERIES.............................................................................................................. 76 E REPRESENTATIVE PHOTOGRAPHS OF ANCHOR SPECIMENS FROM TESTING..........................................................................................................84 F COMPILATION OF PROD UCT APPROVAL TEST RESULTS..............................90 REFERENCE LIST ...........................................................................................................95 BIOGRAPHICAL SKETCH .............................................................................................97

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vi LIST OF TABLES Table page 5-1 Summary of testing progr am for grout product CA ....................................................23 5-2 Grout installation summary .........................................................................................24 6-1 Summary of single anchor test results exhibiting bond failure ...................................32 6-2 Summary of baseline singl e anchor test results...........................................................34 6-3 Summary of multiple anchor test results.....................................................................35 7-1 Summary of tested factor s influencing grout bond strength.......................................41 B-1 Individual baseline and hole dril ling technique anchor test results............................65 C-1 Individual edge dist ance anchor test results................................................................72 D-1 Individual group anchor test results............................................................................77

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vii LIST OF FIGURES Figure page 2-1 Types of anchor systems................................................................................................2 2-2 Examples of typical unheaded and headed grouted anchors .........................................7 2-3 Typical bond failures at the steel/gr out and grout/concrete interfaces for unheaded grouted anchors.............................................................................................7 2-4 Typical bond failure at the grout/concrete interface and concrete cone breakout failure of headed grouted anchors.................................................................................8 3-1 Calculation of AN0 for the CCD method ......................................................................12 3-2 Projected areas for single anchors and anchor groups for the CCD method...............13 3-3 Calculation of AN0 for the uniform bond stress model using the anchor diameter ......14 3-4 Projected areas for single anchors and anchor groups for the uniform bond stress model using the anchor diameter ......................................................................15 3-5 Calculation of AN0 for the uniform bond stress model using the hole diameter ..........15 3-6 Projected areas for single anchors and anchor groups for the uniform bond stress model using the hole diameter ..........................................................................15 5-1 Single anchor test apparatus ........................................................................................26 5-2 Group anchor test apparatus ........................................................................................27 5-3 Minimum reaction positions of test apparatus for headed anchors .............................27 5-4 Diagram of displacement calculati on for individual anchor in group test ..................30 8-1 Critical edge distance of 8 d0 compared to experimental results..................................44 8-2 Critical anchor spacing of 16 d0 compared to experimental results .............................44 8-3 Critical edge distance of 5 d0 compared to experimental results..................................45

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viii 8-4 Critical anchor spacing of 10 d0 compared to experimental results .............................46 B-1 Graphs of test results of first installation of core-drilled anchors...............................66 B-2 Graphs of test results of second installation of core-drilled anchors..........................67 B-3 Graphs of test results of third installation of core-drilled anchors..............................68 B-4 Graphs of test results of first installation of hammer-drilled anchors ........................69 B-5 Graphs of test results of second in stallation of hammer-drilled anchors....................70 C-1 Graphs of test results of core-dri lled anchors installed 4.5 inches away from one edge ........................................................................................................... ..73 C-2 Graphs of test results of core-dri lled anchors installed 6.0 inches away from one edge ........................................................................................................... ..74 C-3 Graphs of test results of core-dri lled anchors installed 7.5 inches away from one edge ........................................................................................................... ..75 D-1 Graphs of results of first core-dri lled anchor group installed with anchor spacing of 5.0 inches................................................................................................... 78 D-2 Graphs of results of second core-drill ed anchor group installed with anchor spacing of 5.0 inches................................................................................................... 79 D-3 Graphs of results of th ird core-drilled anchor gr oup installed with anchor spacing of 5.0 inches................................................................................................... 80 D-4 Graphs of results of first core-dri lled anchor group installed with anchor spacing of 9.0 inches................................................................................................... 81 D-5 Graphs of results of second core-drill ed anchor group installed with anchor spacing of 9.0 inches................................................................................................... 82 D-6 Graphs of results of th ird core-drilled anchor gr oup installed with anchor spacing of 9.0 inches................................................................................................... 83 E-1 Typical grout/concrete bond failure of single core-drilled anchor with grout plug.............................................................................................................. ......84 E-2 Typical grout/concrete bond failure of single anchor with secondary shallow concrete cone ........................................................................................................... ...84

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ix E-3 Grout/concrete bond failure of single core-drilled anchor with secondary shallow cone removed and grout plug exposed..........................................................85 E-4 Typical grout/concrete bond failure of single hammer-drilled anchor with grout plug.............................................................................................................. ......85 E-5 Typical grout/concrete bond failure of single hammer-drilled anchor with secondary shallow concrete cone and grout plug .......................................................86 E-6 Typical grout/concrete bond failure of single core-drilled anchor installed 4.5 inches from one edge with grout plug and diagonal cracking of surrounding concrete................................................................................................................ .......86 E-7 Typical grout/concrete bond failure of single core-drilled anchor installed 6.0 inches from one edge with grout plug...................................................................87 E-8 Typical grout/concrete bond failure of single core-drilled anchor installed 7.5 inches from one edge with grout plug...................................................................87 E-9 Typical surface view of cone failure of quadruple fastener anchor group with anchor spacing of 5 inches..................................................................................88 E-10 Typical dissection view of cone failure of quadrupl e fastener anchor group with anchor spacing of 5 inches.................................................................................88 E-11 Typical grout/concrete failure of quadruple fastener anchor group with anchor spacing of 9 inches.........................................................................................89 F-1 Strength versus curing time for product CA ...............................................................90 F-2 Strength versus curing time for product CG ...............................................................90 F-3 Strength versus curing time for product PB................................................................91 F-4 Comparison of average failure loads for installation with threaded rods and smooth rods......................................................................................................... .91 F-5 Comparison of average bond stresses fo r installation with threaded rods and reinforcing bars .................................................................................................... 92 F-6 Comparison of average failure loads for installation of headed anchors with regular hex nuts and heavy hex nuts...................................................................92 F-7 Comparison of average failure loads for installation in core-drilled and hammer-drilled holes ..................................................................................................93

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x F-8 Comparison of average bond stresses fo r installation in damp and dry holes ............93 F-9 Comparison of average failure loads for tests performed at ambient and elevated temperatures..................................................................................................9 4

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xi Abstract of Thesis Presen ted to the Graduate School Of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Engineering BEHAVIOR AND DESIGN OF GROUT ED ANCHORS LOADED IN TENSION INCLUDING EDGE AND GROUP E FFECTS AND QUALIFICATION OF ENGINEERED GROUT PRODUCTS By Jennifer Lynn Burtz August 2003 Chair: Ronald A. Cook Major Department: Civil and Coastal Engineering Based on experimental test results, a set of design equations were developed for computing the tensile pullout resistance of headed and unheaded single and group grouted anchors. Edge distance and group sp acing effects are considered, and values for the critical edge distance a nd critical anchor spacing are proposed. The results of this testing program, along with those from previ ous experimental programs, were analyzed to ascertain grout susceptibilit y to various installation and in -service factors. Stemming from these results, a series of product approva l tests was proposed to determine if an engineered grout product is suit able for a desired application.

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1 CHAPTER 1 INTRODUCTION A typical grouted anchor consists of a steel rod and the gr out product installed into a hole drilled in hardened concrete. Grout products can be either cementitious or polymer based and installed into the hole with a headed or unheaded anchor. This paper explores the behavior of both single and groups of grouted an chors loaded in tension in uncracked concrete. The parameters consid ered are hole drilling technique, anchor diameter, edge effects, and group effects. These results, along w ith the results from existing test databases, form the basis fo r a proposed design model for grouted anchors and product approval tests for engineered grout products. The American Concrete Institute (ACI) 318-02 (ACI 2002) includes a new Appendix D addressing anchorage to concrete Design procedures for cast-in-place anchors and post-installed mech anical anchors are included in Appendix D. As a result of extensive testing, the AC I 318 committee is currently working on including adhesive anchors in Appendix D. Grouted anchors are also being considered for inclusion.

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2 CHAPTER 2 BACKGROUND 2.1 Types of Anchor Systems Anchor fastenings to concrete can be di vided into two main categories: cast-inplace and post-installed anchors. Figure 2-1 presents a diagram summarizing the types of anchors available and the pr oducts used for installation. Figure 2-1 Types of anchor systems Cast-in-place anchors are inst alled by first connecting them to the formwork prior to pouring concrete. A cast-in-place anchor is typically composed of a headed steel bolt or stud. The main load transfer mechanis m is through bearing on the head. Extensive testing has been performed on cast-in-place anchors, and a design model has been Cast-in place Post-installed Expansion Mechanical Bonded Adhesive Grouted Polymer Hybrid System Cementitious Polymer Anchor Systems Undercut Headed J & L Bolts Studs

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3 developed to accurately predict their beha vior. Systems comprised of cast-in-place anchors behave predictably but are fixed in their location after th e concrete is cast. Post-installed anchors offer more flexib ility, and their use is now common. Systems of post-installed an chors include: mechanical (expansion and undercut) and bonded (adhesive and grouted) anchors. Expa nsion anchors are installed by expanding the lower portion of the an chor through either torque -controlled or displacementcontrolled techniques, and load is transferred through fric tion between the hole and the expanded portion of the anchor. Undercut an chors are installed in a similar manner to expansion anchors, but they possess a slightly oversized hole at the base of the anchor embedment. Load is transferred through bear ing of the base of the undercut anchor on the hole. Both adhesive a nd grouted anchors fall under th e heading of bonded anchors. This paper is primarily concerned with th e comparison of grouted anchors to cast-inplace and adhesive anchors. 2.2 Bonded Anchors Post-installed bonded anchors can be categor ized as either adhesive or grouted. An adhesive anchor can be either an unheaded threaded rod or a de formed reinforcing bar and is inserted into hardened concrete in a predrilled hole that is typically 10 to 25 percent larger than the diam eter of the anchor. These anchors are bonded into the hole using a two-part structural a dhesive consisting of a resin and a curing agent to bind the concrete and steel together. Contrastingly, a grouted anchor can be an unheaded threaded rod, a deformed reinforcing bar, a headed bolt, a headed stud, a smooth rod with a nut on the embedded end, or a threaded rod with a nut on the em bedded end. Grouted anchors are installed into hardened concrete in predrilled holes th at are typically 50 to 200 percent larger than

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4 the diameter of the anchor. For the purposes of this paper, the break point between an adhesive anchor and a grouted an chor is when the hole diameter is equal to one and a half times the anchor diameter; all anchors installed in holes greater than or equal one and a half times the anchor diameter shall be considered as grouted anchors. Engineered grouts can be cementitious or polymer based. Cementitious grouts are composed of primarily fine aggregates, por tland cement, and water; polymer grouts are similar in nature to the structural adhesive used to bind adhesive anchors to concrete but also contain a fine aggregate component. 2.2.1 Adhesive Anchors The curing time of adhesive products is rapid, which makes them ideal for situations requiring a quick set. Different products can be used to install adhesive anchors. These products can be polymers (e poxies, polyesters, or vinylesters) or hybrid systems. Cook et al. (1998) explain that when the resin and curing agent are mixed, the products undergo an exothermic reaction result ing in the formation of a polymer matrix that binds the anchor and the concrete togeth er. Adhesive anchors are typically installed in clean dry holes to attain maximum bond strength. Applied load is transferred from the adhesive anchor to the concrete by one of two mechanisms: mechanical interlock or chemical binding to the concrete. Cook et al. (1998) proposed a model to design adhesive anch ors and to predict anchor strength. This model was develope d by comparing the test results from an international test database of single adhesive anchors to several di fferent design models. The uniform bond stress model was proposed and provided the best fit to the database.

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5 McVay et al. (1996) also showed the uniform bond stress model to be rational through comparison of predictions from nonlinear comp uter analysis to experimental results. Product approval standards and guidelines fo r adhesives currently exist in several published documents. The International Congress of Building Officials Evaluation Service (ICBO ES) AC58 (ICBO ES 2001) lists and describes various tests for evaluating adhesive performance under different anchor c onfigurations and inst allation conditions. The mandatory tests include single anchor test s in tension and in sh ear, critical edge distance tests for single anchors in tension, tests for critical anchor spacing in anchor groups, and tests for sensitivity to in-service temperature conditions. The Florida Method of Test FM 5-568 (FDOT 2000) describes the te sts required by the Florida Department of Transportation (FDOT) for determining the bond strength and sensitivity to installation and service conditions of adhesive bonde d anchors and dowels. This document references both the American Society for Testing and Materials (ASTM) E 488-96 (ASTM 2001d) and ASTM E 1512-01 (ASTM 2001e) in respect to how tests on anchor systems should be performed. The FM 5-568 recommends that tension tests, damp hole installation tests, elevated temperature tests, horizontal orientation te sts, short-term cure tests, and long-term loading tests be perf ormed on anchor systems. Cook and Konz (2001) experimentally investigated the sens itivity of 20 adhesive products to various installation and service conditions through 765 tests. Installation factors examined included variations in the condi tion of the drilled hole, conc rete strength, and concrete aggregate. Service conditions considered in cluded short-term cure and loading at an elevated temperature.

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6 2.2.2 Grouted Anchors Grouted anchors can be bonded to concrete with either polymer or cementitious products. Anchors bonded with a polymer grout are intended to be installed into dry holes and under similar conditions as adhesive anchors. Polymer grouts are very similar to adhesive products in composition. Both polymer adhesive products and polymer grouts contain a resin component and a curi ng agent (hardener), and polymer grouts are additionally comprised of a third component, a fine aggregate that se rves as a filler. Polymer grouts usually have a rapid cure ti me, and anchors can be loaded hours after installation. The dry components of cementitious grout products are usually prepackaged. Water is added at the time of installation, acco rding to the manufacturer’s guidelines, to achieve the desired viscosity. Anchors bonded with a cementitious gr out are intended to be installed in clean, damp holes in order to prevent excess water loss into the concrete from the grout, which would reduce the bond stre ngth of the grout. To ensure that this does not occur, the holes are usually satura ted by filling them with water for a minimum of 24 hours prior to installation unless otherwise stat ed in the manufact urer’s directions. Grouted anchors can be installed with or without a head at the embedded end, as shown in Figure 2-2. The presence of a head, or the lack thereof, affects the load transfer mechanism from the anchor to the grout. Howe ver, load is transferred from the grout to the concrete primarily through bond and mechanic al interlock regardless of the presence or absence of a head. Unheaded anchors installed by using a threaded rod or a deformed reinforcing bar transfer load to the grout through bond and mechanical interlock. These anchors are

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7 expected to experience a bond failure either at the steel/grout interface or the grout/concrete interface with a secondary sh allow concrete cone. Previous testing performed at the University of Florida by Kornreich (2001) and Zamora (1998) confirms that these failure modes occur. Figure 23 shows the typical failure modes for unheaded grouted anchors. Figure 2-2 Examples of typical unheaded and headed grouted anchors Figure 2-3 Typical bond failures at the stee l/grout and grout/concrete interfaces for unheaded grouted anchors Headed anchors installed with a headed bolt or a smooth rod with a nut at the embedded end of the anchor transfer load to the grout through b earing on the head. Unheaded g routed anchor Headed g routed anchor h e f d 0 > 1.5d d 0 > 1.5d Bond failure at steel/ g rout interface Bond failure at grout/concrete interface

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8 These anchors are expected to fail either in a bond failure at the gr out/concrete interface with a secondary shallow cone or in a fu ll concrete cone breakout depending on the bond strength of the grout. Failure at the steel/g rout interface is precluded due to the presence of the head. Similar to unheaded grouted anchors, previous testing performed at the University of Florida by Kornreich (2001) and Zamora (1998) confirms these failure modes occur. Figure 2-4 shows the typical failure modes for headed grouted anchors. Figure 2-4 Typical bond failure at the grout /concrete interface and concrete cone breakout failure of headed grouted anchors 2.3 Previous and Current Studies with Grouted Anchors Experimental and analytical studies fo cusing on the strength and behavior of grouted anchors under tensile load have been presented in published literature. In the earlier stages of grouted anc hor research, the theoretical be havior of polymer grouts was examined. James et al. (1987) presented an analysis of post-inst alled epoxy (polymer) grouted anchors in reinforced concrete ba sed on linear and non linear finite element models and comparisons to previously re ported experimental data. Parameters considered in this study included various ra tios of embedment depth to bolt diameter, different grout properties, and two concrete failure theories: the maximum tensile stress criteria and the Mohr-Coulomb criteria. According to James et al. (1987), when bond Bond failure at grout/concrete interface Concrete breakout failure

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9 failure occurs at the grout/concrete interface, testing has shown that the load capacity was directly related to the size of the drilled hole. As the hole size increased, the load capacity of the epoxy was increased due to th e increase in bond area and displacement of the head of the bolt also increased. If hi gher strength grouts are utilized, the shear strength of the concrete will control, a nd failure at the grout/concrete interface is precluded. Additionally the location of the reaction ring was crucial because, if it was too close to the anchor, it could result in falsely inflated anchor strength. Other studies were experimental in natu re and examined the behavior of polymer and cementitious grouts while varying physical parameters. One such experimental study was reported by Zamora (1998) and contai ned 290 tension tests on post-installed unheaded and headed grouted anchors. Th e bond strength of unheaded and headed grouted anchors was tested for influence of anchor diameter, hole diameter, embedment depth, grout product (cementitious or polyme r), installation conditions, and concrete strength. A product approval test program fo r grout products was also investigated, and the following tests were performed: damp hole installation, elevated temperature, threaded rod versus deformed reinforcing bar, regular hex nut versus heavy hex nut, and a test series to establish bond st ress at the grout concrete inte rface. Portions from Zamora (1998) pertaining to behavior and design of grouted anchors installed in uncracked concrete away from a free edge and under tens ile load are presented in Zamora et al. (2003). Test results showed unheaded grouted anchors experienced a bond failure and, in general, behaved similar to adhesive anchor s, and headed grouted anchors experienced either a bond failure at the grout/concrete in terface or a concrete cone breakout. This study recommended that the strength of unheaded grouted anchors be predicted using the

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10 uniform bond stress model; the strength of headed grouted anchors was recommended to be taken as the smaller strength of a bond failure at the grout/concrete interface or a concrete cone breakout. Differences in bond strengths were found to exist between installation of threaded rods and deformed reinforcing bars when cementitious grouts were utilized. Cementitious grouts experi enced a lower bond strength when installed using a heavy hex nut as opposed to a regular hex nut; the effect wa s opposite for the one polymer grout product tested. Additionally, tests indicated that the bond strength of polymer grouts was generally reduced with an increase in temperature or damp hole installation. These resu lts are discussed in detail in Chapter 7. In a more recent experimental program Kornreich (2001) tested post-installed headed and unheaded grouted anchors by vary ing several parameters. Tests included: grout strength versus curing time, bond of grout to smooth steel, bond of grout to concrete, and basic bond strength at the st eel/grout interface. Based on the results obtained, recommended design equations were presented including capacity reduction factors. In the present paper, the results of pos t-installed headed grouted anchor tests examining the effects of hole drilling techniqu e, edge distance eff ects, and group spacing effects are presented. The results from previ ous studies and existi ng test databases on headed and unheaded grouted anchors a nd cementitious and polymer grouts are considered. All of this information is combined into recommendations for design specifications for grouted anchors and pr oduct approval tests for engineered grout products.

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11 CHAPTER 3 BEHAVIORAL MODELS 3.1 General In previous testing programs, grouted anchors were expected to behave in a similar manner to either cast-in-place headed anchors or post-insta lled adhesive anchors depending on whether the anchors were headed or unheaded. Both cast-in-place headed anchors and post-installed adhesive anchor s have been extensively studied, and behavioral models have been developed th at accurately predict anchor strength. The Concrete Capacity Design (CCD) method and the uniform bond stress model were therefore used to evaluate the behavior of grout ed anchors in this test program, as well as in previous test programs. The development, applicability, and genera l equations of these models are presented in the following sections. 3.2 Concrete Capacity Design (CCD) Method Fuchs et al.(1995) first proposed th e CCD method in 1995. This model was created to predict the failure loads of cast-in-place headed anchors and post-installed mechanical anchors loaded in tension or in shear that form a full concrete cone. The mean tensile capacity for single cast-in-place headed anchors installed in uncracked concrete is predicted by the following equations: 5 1 0 ,' 40ef c ch f N (lbf) (1a) or

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12 5 1 0 ,' 7 16ef c ch f N (N) (1b) Similarly, the CCD method predicts the tensile capacity of cast-in-place headed anchor groups using the following equations: 0 , 0 c e c N N cN A A N (lbf or N) where ef e ch c 5 1 3 0 7 0, (2) Figures 3-1 and 3-2 are ad apted from figures found in ACI 318-02 Appendix D (ACI 2002). Figure 3-1 illustra tes the calculation of AN0. Figure 3-2 depicts the projected areas for single anchors and groups of an chors for the CCD method as well as the calculation of AN. Figure 3-1 Calculation of AN0 for the CCD method 3.3 Uniform Bond Stress Model As mentioned in the previous chapte r, Cook et al. (1998) compared several different models, and the unifo rm bond stress model using th e anchor diameter was found to be the best fit to the test database. As a result, a uniform bond stress can be assumed

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13 along the entire embedment depth of the adhesi ve anchor and accurately predict the bond strength when the embedment length does not exceed 25 times the anchor diameter. For Figure 3-2 Projected areas for single anchor s and anchor groups for the CCD method grouted anchors with the hole di ameter greater than or equal to one and a half times the anchor diameter, bond failure can be distinguishe d at either the steel/g rout interface or at the grout/concrete interface. Zamora et al. ( 2003) presented two variations of this model to account for failure at the inner and outer surfaces of the bonding agent as shown in the following equations for single anchors installed away from a free edge: efh d N 0 (lbf or N) (3) efh d N0 0 0 ,0 (lbf or N) (4) Lehr and Eligehausen (2001) proposed an extension of the uniform bond stress model for unheaded adhesive anchor groups sh own below in Equation (5). This equation could also be applied to gr outed anchor groups that e xperience a bond failure at the steel/grout interface. When bond failure occurs at the grout/concrete interface, Equation (5) may be revised as shown in Equation (6). In this way, the tens ile capacity of anchor groups can be predicted by the uniform bond st ress model using the following equations:

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14 0 , 0 N A A Ne N N (lbf or N) where d ce8 3 0 7 0, (5) 0 , 00 0 0 N A A Ne N N (lbf or N) where 0 ,8 3 0 7 00d ce (6) Figures 3-3 through 3-6 are adapted fo r the uniform bond stress model from similar figures for the CCD method f ound in ACI 318-02 Appendix D (ACI 2002). Figures 3-3 and 3-5 show the calculation of AN0 for bond failure at the steel/grout and grout/concrete interfaces, respectively. Figures 3-4 and 3-6 depict the projected areas for single anchors and groups of anchors for th e uniform bond stress model as well as the calculation of AN at the steel/grout and grout/c oncrete interfaces, respectively. Figure 3-3 Calculation of AN0 for the uniform bond stress model using the anchor diameter 8 d 8 d 8 d 8 d AN0 = [2(8)d][2(8)d] = 256 d2

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15 Figure 3-4 Projected areas for single anchor s and anchor groups for the uniform bond stress model using the anchor diameter Figure 3-5 Calculation of AN0 for the uniform bond stress model using the hole diameter Figure 3-6 Projected areas for single anchor s and anchor groups for the uniform bond stress model using the hole diameter Since adhesive anchors are typically inst alled in holes with diameters only 10 to 25 percent larger than the anchor diameter, Za mora (1998) conjectured that it is difficult to differentiate between a failure at the steel/grout interface and the grout/concrete interface. However, grouted anchors are usually installed in holes with diameters ranging 8 d0 8 d0 8 d0 AN = (c1 + 8d0)(2 x 8d0) If c1 < 8d0 A N c1 AN = (c1 + s1 + 8d0)(c2 + s2 + 8d0) If c1 and c2 < 8d0 and s1 and s2 < 16d0 A N 8 d0 s1 c1 8 d0 c2 s2 8 d0 8 d0 8 d0 8 d0 AN0 = [2(8)d0][2(8)d0] = 256 d0 2 8 d 8 d 8 d AN = (c1 + 8d)(2 x 8d) If c1 < 8d A N c1 AN = (c1 + s1 + 8d)(c2 + s2 + 8d) If c1 and c2 < 8d and s1 and s2 < 16d A N 8 d s1 c1 8 d c2 s2

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16 from 50 to 200 percent larger than the anchor diameter. The larger hole size makes it easier to determine at which in terface a bond failure occurred. Equation (3) has been shown by Cook et al (1998) to be a good approximation of single adhesive anchor tensile strength even though the interface at which bond failure occurred is not always readily apparent. Si milarly, Equation (5) is applicable to groups of adhesive anchors according to Section 7.12 of the Structures Design Guidelines for Load and Resistance Factor Design (FDOT 2002 b). In general, both Equation (3) and Equation (4) are applicable to evaluating the strength of single grout ed anchors since the interface at which bond failure occurred is more easily observed. For headed grouted anchors experiencing bond failure, only E quation (4) should be considered when determining the tensile strength since failure at the steel/grout interface is precluded by the presence of the head. The applicability of Equation (6) to headed grouted anchor groups will be examined in this test program.

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17 CHAPTER 4 DEVELOPMENT OF TEST PROGRAM 4.1 General The objective of this test program was to perform addi tional grouted anchor tests in order to provide a more complete picture of the behavior of engine ered grout products. The results of these tests, along with current te st databases, will be used to evaluate the applicability of existing desi gn models, to recommend a design model to predict strength of grouted anchors, and to advocate a series of product approval tests to perform in the assessment of engineered grouts. Previous test programs have not fully addressed the failure mode of grouted anchor s at the grout/concrete interfa ce. In order to develop a complete design model, this failure mode needs to be further examined. To investigate the behavior of grouted anchors experiencing this failure mode, this test program chose certain parameters in an attempt to force a failure at the grout/concrete interface. Concrete strength was selected to prevent a concrete cone breakout failure. All anchor specimens were post-installed with a non-shrink cementitious grout product, CA (cementitious grout product A) for the purposes of this paper, as headed anchors to preclude a failu re at steel/grout interface. In addition, the hole diameter was minimized, allowing only a small clearance between the heavy hex nut of the headed anchor and the side of the hole, to promote a grout/concrete bond failure. To properly evaluate this failure mode, ot her anchor parameters were varied. The experimental program included factors ofte n encountered during de sign and installation of anchors including hole dri lling technique (diamond-headed core drill or rotary impact

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18 hammer drill), anchor diameter, edge dist ance effects, and group spacing effects. Embedment depth was held constant. The te st program was separated into two primary sections: single and group grouted anchor test s. In general, each single anchor series consisted of at least three re petitions, and each group anchor series consisted of three repetitions. 4.2 Single Grouted Anchor Test Program In the single grouted anchor test program, three separate inst allations of headed grouted anchors were conducted. Each installation contained a baseline series of anchors grouted into core-drilled holes. All baseline series consisted of three repetitions except the first baseline series, which contained five tests. Other installation parameters were explored in addition to the base line series of tests to esta blish which factors affect the general anchor strength and to quant ify this effect where present. The first installation in the single groute d anchor test program was comprised of ten anchors, separated into tw o series of five, and aimed to test the potential effects of hole drilling techniques. All ten anchors were 0.625 inch (1 5.9 mm) in diameter, smooth steel rods with threaded ends, and headed using a heavy hex nut. In addition, the embedment depth was 5 inches (127.0 mm) measur ed from the top of th e nut to the top of the concrete, and the edge distance of 12 inches (304.8 mm) was sufficiently large to eliminate concern of edge distance effects. Th e baseline series consisted of five of the aforementioned anchors damp-installed into core-drilled holes 1.5 inches (38.1 mm) in diameter. The second single anchor series in the first installation va ried one factor from the baseline series; these five anchors were damp-installed into hammer-drilled holes 1.5 inches (38.1 mm) in diameter.

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19 The second installation in this test pr ogram consisted of 11 anchors with the purpose of examining edge effects and to furt her inquire into eff ects arising from hole drilling techniques. All anchor s in this installation were 0.75 inch (19.1mm) in diameter, smooth steel rods with threaded ends, and headed using a heavy hex nut. As in the previous installation, all anc hors were embedded 5 inches (127.0 mm), and all holes were 1.5 inches (38.1 mm) in diameter. The baseline series consisted of three anchors dampinstalled into core-dri lled holes. The second series in this installation contained three anchors damp-installed into hammer-drilled ho les. All anchors in both of these series were installed a minimum of 15 inches (381 mm ) from the edge of the concrete block to eliminate the possibility of edge effects. The final test series on this installation was comprised of five anchors damp-installed in proximity to a single edge. These anchors were 7.5 inches (190.5 mm) from one edge and a minimum of 24 inches (609.6 mm) from all additional edges. The third installation contained 13 anc hors and endeavored to observe edge distance effects in more detail. All anchor s in this installation were 0.75 inch (19.1 mm) in diameter, smooth steel rods with threaded ends, and headed with a heavy hex nut. Again, all anchors were embedded 5 inches ( 127.0 mm); all holes were core-drilled and 1.5 inches (38.1 mm) in diameter. The baseline series consisted of three anchors dampinstalled and placed a minimum of 15 inches (381 mm) from all edges to preclude this type of effect. The two edge effects series included five anchors damp-installed 6 inches (152.4 mm) from one edge and five anchors damp-installed 4.5 inches (114.3 mm) from one edge. All ten anchors were placed a minimum of 24 inches (609.6 mm) from the remaining edges.

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20 4.3 Group Grouted Anchor Test Program In the group grouted anchor test progra m, two separate installations of quadruple fastener headed grouted anchor groups were carried out. In order to evaluate the group effect, the single anchor strength N0 must be established. For this reason, a baseline series, as discussed in the previous secti on, was installed in the same concrete on the same day as the group specimens. This allowe d for a direct compar ison of group strength to the strength of a single anchor. The first quadruple fastener series of three tests was installed in the first installation. Each anchor group contained f our anchors 0.625 inch (15.9 mm) in diameter with smooth steel shafts, threaded ends, and headed using heavy hex nuts. All anchors were embedded 5 inches (127.0 mm) deep in holes 1.5 inches (38.1 mm) in diameter and spaced 5 inches (127.0 mm) from each adjacent anchor to form a square. The second series of three tests was insta lled in the third installation. Each anchor group included four anchors 0.75 inch (19.1 mm ) in diameter with smooth steel shafts, threaded ends, and headed using heavy hex nut s. All anchors were embedded 5 inches (127.0 mm) deep in holes 1.5 inches (38.1 mm) in diameter and spaced 9 inches (228.6 mm) from each adjacent anchor to form a square.

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21 CHAPTER 5 IMPLEMENTATION OF TEST PROGRAM 5.1 General This test program consisted of two c oncrete pours and three sets of anchor installations. All tests were unconfined tension tests and performed in general accordance with applicable sections of ASTM E 488-96 (ASTM 2001d) and ASTM E 1512-01 (ASTM 2001e). General test methods for single and group post-installed and cast-in-place anchorage systems are presented in ASTM E 488. More specific testing procedures for bonded anchors ar e addressed in ASTM E 1512. 5.2 Concrete For both pours, concrete was ordered from a local ready-mixed plant that batched, mixed, and delivered the concre te to the University of Fl orida Structures Laboratory. The first pour occurred on February 22, 2002; the second pour occurred on July 18, 2002. All concrete was FDOT Class II to achiev e the compressive strengths necessary to preclude a concrete cone breakout failur e. The mix design specified a 28-day compressive strength of 3400 psi, but cylinde r tests yielded a compressive strength of 6460 to 7670 psi. Wooden formwork was utiliz ed to construct the seven rectangular blocks in each pour: six blocks 4x4x1.25 feet (1219x1219x381 mm) and one block 4x8x1.25 feet (1219x2438x381 mm). Each block cont ained a single steel reinforcing mat to accommodate handling stresses and prevent cracking. The reinforcement was located 9 inches (228.6 mm) down from the top surface of the concrete. This distance was greater than the embedment de pth of the anchors, which a voided any interactions during

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22 testing and failure. After the concrete was poured, consolidated, and smoothed, the blocks were covered with plastic sheets for three days to cure; the blocks were then removed from the formwork. Blocks were al lowed to sit for a minimum of 28 days after pouring to attain adequate stre ngth before drilling holes. C oncrete compressive strength was determined through cylinder tests perf ormed in accordance with ASTM C 39-01 (ASTM 2001a). 5.3 Specimen Preparation Once the concrete had sufficiently cured, the required holes for the anchors were drilled into the concrete blocks by using either a core drill or a hammer drill. The holes were drilled deeper than the desired embedm ent depth to provide room for the nut, the end of the anchor, and a pocket of grout at the base of each hole. A summary of the dimensions, hole drilling technique, type of an chor installed, and the type of test being performed can be found in Table 5-1. After the completion of hole drilling, th e holes were cleaned according to the grout manufacturer’s directions. This was accomplished by first vacuuming out the loose matter resulting from the drilling process. Next, the holes were flushed several times with clean water, and the water was vacuum ed out each time. The holes were then brushed, while damp, using a bottlebrush in accordance with the grout manufacturer’s directions. The holes were flushed several more times with clean water, and the water was vacuumed out each time. Then the holes were prepared for installation according to the grout manufacturer’s instructions. This consisted of filling the cleaned holes with water for a minimum of 24 hours to allow for a damp hole installation. The holes were sealed with duct tape to prevent foreign ma tter from entering. Just prior to anchor installation, the duct tape was removed and excess water was vacuumed out. The anchors

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23 were cleaned prior to installa tion using paint thinner as a de greaser accordi ng to the grout manufacturer’s recommendations. Table 5-1 Summary of testing program for grout product CA Installation # Tested Effect Hole Type Anchor Diameter d in (mm) Hole Diameter d0, in (mm) Embedment Depth hef, in (mm) Edge Distance c in (mm)a Spacing s in (mm)b # of Tests n 1 Baseline Core 0.625 (15.9) 1.5 (38.1) 5.0 (127.0) N/A N/A 5 1 Hammer Hammer 0.625 (15.9) 1.5 (38.1) 5.0 (127.0) N/A N/A 5 1 Group Core 0.625 (15.9) 1.5 (38.1) 5.0 (127.0) N/A 5.0 (127.0) 3 2 Baseline Core 0.750 (19.1) 1.5 (38.1) 5.0 (127.0) N/A N/A 3 2 Hammer Hammer 0.750 (19.1) 1.5 (38.1) 5.0 (127.0) N/A N/A 3 2 Edge Core 0.750 (19.1) 1.5 (38.1) 5.0 (127.0) 7.5 (190.5) N/A 5 3 Baseline Core 0.750 (19.1) 1.5 (38.1) 5.0 (127.0) N/A N/A 3 3 Edge Core 0.750 (19.1) 1.5 (38.1) 5. (127.0) 4.5 (114.3) N/A 5 3 Edge Core 0.750 (19.1) 1.5 (38.1) 5.0 (127.0) 6.0 (152.4) N/A 5 3 Group Core 0.750 (19.1) 1.5 (38.1) 5.0 (127.0) N/A 9.0 (128.6) 3 a Edge distances designated as N/ A refer to anchors installed at > 8 d0. b Spacing between anchors designated as N/A refers to anchors installed at > 16 d0. 5.4 Installation Procedure Three separate anchor installations were performed at the University of Florida Structures Laboratory in 2002. All installa tions were conducted similarly, and grout cubes were also cast whenever anchors were installed. The compressi ve strength of the grout product was determined through the tes ting of grout cubes in accordance to ASTM C 109-99 (ASTM 2001b). The holes were filled approximately 75% full, and the headed anchors were inserted. The anchors were shifted about in the holes to remove any entrapped air and then supported in positi on at the proper embedment depth. Moist curing occurred for seven days by wrapping th e anchors with saturated paper towels and covering the slabs with plastic sh eets to retain the moisture. For the first installa tion, a field representative from the grout manufacturer was on site to oversee, train, and assist in the instal lation process. This ensured that the grout

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24 was proportioned, mixed, and installed to th e manufacturer’s specifications. For all installations, the grout product CA was mixed to a fluid consistency with a high torque electric drill and mixing paddle for five minut es. The grout mixture was then subjected to a standard 1725 mL flow cone test in accordance with ASTM C 939-97 (ASTM 2001d). The grout product, date of installati on, flow rate, and minimum cure time from all three installations are summarized in Ta ble 5-2. The flow rates fell within the manufacturer’s requirements of 25 to 30 seconds with a tole rance of 1 second. Table 5-2 Grout installation summary Installation # Date of Installation Grout Product Flow Rate (seconds) Minimum Grout Cure Time (days) 1 April 11, 2002 CA 31 28 2 July 11, 2002 CA 26 14 3 August 22, 2002 CA 25 14 5.5 Apparatus A schematic diagram of the equipment us ed in the tension tests for the single grouted anchors can be seen in Figure 5-1. The tests performed were unconfined, since the position of the reactions was in accordance with ASTM E 488. Figure 5-3 shows the positions of these reactions in relation to the anchor specimen. The equipment setup was designed to allow direct measur ement of the load and displ acement of the single anchor specimens. The test apparatus c onsisted of the following parts: Reaction ring efh Diameter 4 Two steel wide range flange section Three steel bearing plat es for center apparatus One 120 kip (534 kN) hydraulic ram One 200 kip (890 kN) load cell

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25 One 1.125 inch (28.6 mm) diameter pull bar/coupling rod and retaining nut Coupling nut Steel plate for Linear Variable Differential Transformers (LVDT’s) Two LVDT’s (2 inch range) The edge distance tests used two steel channe ls instead of the reac tion ring due to the anchor proximity to one edge of the concrete block. The equipment used in the group grouted anchor tension tests is shown in the schematic diagram in Figure 5-2. These tests were also unconfined due to the position of the reactions as shown in Fi gure 5-3. The equipment setup was designed to allow direct measurement of the load and displacement for each individual anchor as well as the whole group. The test apparatus consisted of the following parts: Reaction ring s h Diameteref 4 Two steel wide range flange section Two steel channels Three steel bearing plat es for center apparatus One pull plate 12x12x2 inches (304.8x304.8x50.8 mm) One 120 kip (534 kN) hydraulic ram One 200 kip (890 kN) load cell Four 100 kip (445 kN) load washers One 1.125 inch (28.6 mm) diameter pull bar/coupling rod and retaining nut

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26 Four steel angles Two steel frames for potentiometers Four steel bearing plates for single anchors Four potentiometers (1.5 inch range) C-Clamps of various sizes Figure 5-1 Single anchor test apparatus 5.6 Loading Procedure To pull out a single grouted anchor, the anchor was connected to the coupling rod using a coupling nut. The reacti on ring/steel channels and steel flanges were arranged to provide an unconfined test surface. The hydraulic ram was placed atop these supports so that the pull rod passed through its center. The load cell was placed between two bearing plates above the hydraulic ram. Finally, a re taining nut was tightened down the coupling rod to the topmost bearing plate, and the LVDT’s we re secured in position. PullBar Load Cell Hydraulic Ram Coupling Nut LVDT LVDT Plate Reaction Ring Concrete Block Test Anchor Grout Layer

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27 Figure 5-2 Group anchor test apparatus Figure 5-3 Minimum reaction positions of test apparatus for headed anchors Load Cell Hydraulic Ram Steel Channel Load Washer Steel Pull Plate Pull Bar Potentiometer Reaction Rin g Test Anchor Grout La y er Concrete Block h ef Reaction Reaction d 0 2 he f d 2 he f

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28 The hydraulic ram was powered and advanced using a 10,000 psi (68,950 MPa) electric pump. The pump was outfitted with tw o valves. The first controlled the supply to the ram from the pump. The other regulated a bypass from the ram to the oil reservoir. These valves were manually adjusted to contro l the load applied to the anchor specimen. This setup was used in tandem with a data acquisition system capable of continuously measuring and recording the lo ad and displacement readings. The typical single anchor testing pr ocedure contained the following steps: 1. Assembling the test a pparatus as described above 2. Start data acquisition a nd LabVIEW software (NI 1999) 3. Adjust the LVDT’s to be in range 4. Start pump and pull out anchor 5. Stop test and disassemble apparatus The loading procedure for the group tests wa s similar to the singl e anchor tests. Each anchor passed through holes in the pull plate, and th e coupling rod passed through the center hole and was secured with a nut. A load washer was placed on top of each anchor and secured with a bearing plate and a nut. The rest of the test apparatus was assembled as shown in Figure 5-2. The hydrau lic ram was operated in the same manner as in the single anchor tests. The data acq uisition program was also similar but modified to record the readings from the main load cell, the four load wa shers, and the four potentiometers. The typical group anchor testing pro cedure contained the following steps: 1. Assembling the test a pparatus as described above 2. Start data acquisition and LabVIEW software (NI 1999)

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29 3. Adjust the potentiometers to be in range 4. Start pump and pull out anchor 5. Stop test and disassemble apparatus 5.7 Data Reduction 5.7.1 Displacement Calculations for Single Anchor Tests Single anchor specimens were located directly under the coupling rod. Two LVDT’s were used to measure displacemen t readings. The displacement of a single anchor during testing was calculated by taking the mean of these two readings. 5.7.2 Displacement Calculations for Group Anchor Tests For each test conducted, the potentiometers were placed at the same location on the pull plate. This position was 5 inches (127 mm) measured from the center of the pull plate through the cen ter of the sides and 7.07 inches (179.6 mm) measured from the center of the pull plate through the corners. Thus, the poten tiometers formed a square 10 inches (254 mm) on each side. All anchor displacements were calculated assuming that the pull plate was rigid. The deflection of each anchor relative to the concrete block was found using displacement readings and the ge ometry of the test setup. The overall displacement of the group wa s computed as the mean of the four potentiometers: 44 3 2 1d d d d dtot (inches or mm) (7) The displacement of the single anchors within the group was calculated according to the test geometry as shown in Figure 5-4:

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30 Figure 5-4 Diagram of displa cement calculation for individu al anchor in group test 07 7,s d d d dtot poten n tot n (inches) (8a) or 6 179,s d d d dtot poten n tot n (mm) (8b) 7.07 inches s dtot d n dn,poten Steel Pull Plate Potentiometer Pull Rod Test Anchor Grout Layer

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31 CHAPTER 6 TEST RESULTS 6.1 General The following sections provide a summary of all test series performed. All tests were performed using the same cementitious grout product, CA. A total of three installations were performed. All anchors were post-installed as headed with an effective embedment depth of 5 inches. Appendix B provides the load-displacement graphs and detailed results for baseline and hole dril ling technique anchor tests. The loaddisplacement graphs and detailed results for an chors installed near one edge are presented in Appendix C. Finally, Appendi x D contains the load-displacement graphs and detailed results for the quadruple fast ener group anchor tests. 6.2 Single Grouted Anchor Test Results Three types of single anchor tests were pe rformed. First, baseline anchors were installed in core-drilled holes. Second, anchors testing the e ffects of hole drilling technique were installed in hammer-drilled hol es. Finally, anchors we re installed in coredrilled holes at various distances from one e dge of the concrete block and subsequently tested. Table 6-1 provides a summary of the test results for each type of single anchor test performed that resulted in bond failure (i.e tests exhibiting steel failure are excluded from Table 6-1). In general, single anchor s experienced a failure at the grout/concrete interface accompanied frequently by the formation of a shallow secondary concrete cone as evidenced by the diagonal cracking that wa s observed in the conc rete after testing.

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32 Frequently, this secondary concrete cone did not remain attached to the anchor during the tension tests, and cracking and spalling of th e concrete was observed on the surface of the concrete block in addition to the internal diagonal crack s aforementioned. Photographs of representative failed specime n are contained in Appendix E. Table 6-1 Summary of single anchor test results exhibiting bond failure Installation # Test Series Tested Effect N0 kips (kN) Abond in2 (mm2) 0 psi (MPa) COV # of Tests in Calculation 1 CD 1 Baseline 29.4 (131) 23.6 (15200) 1250 (8.60) 0.046 5 1 HD 1 Hammer 30.3 (135) 23.6 (15200) 1290 (8.90) 0.012 2 2 CD 2 Baseline 35.1 (156) 23.6 (15200) 1490 (10.3) 0.040 3 2 HD 2 Hammer 29.0 (129) 23.6 (15200) 1230 (8.50) 0.326 3 2 E 7.5 Edge 7.5 31.9 (142) 23.6 (15200) 1350 (9.30) 0.099 5 3 CD 3 Baseline 39.3 (175) 23.6 (15200) 1670 (11.5) 0.097 3 3 E 4.5 Edge 4.5 28.7 (128) 23.6 (15200) 1220 (8.40) 0.086 5 3 E 6.0 Edge 6.0 32.5 (145) 23.6 (15200) 1380 (9.50) 0.070 5 For the first installation, the average bond stress for the baseline series of coredrilled holes was 1250 psi (8.60 MPa) with a coefficient of variation of 0.046. For the test series containing hammer-d rilled holes, three of the sp ecimens experienced a steel failure at a level below the ultimate anchor stress capacity specified by the manufacturer. The average bond stress for the remaining tw o specimens installed in hammer-drilled holes was 1290 psi (8.90 MPa) with a coeffi cient of variation of 0.012. Normalizing the mean of the hammer-drilled series with the m ean of the baseline series yields a ratio of 1.03 times the baseline series bond stress. In the second installation, the average bond stress for the baselin e series of coredrilled holes was 1490 psi (10.3 MPa) with a coefficient of variation of 0.040. Anchors installed in hammer-drilled holes were also tested and resulted in an average bond stress of 1230 psi (8.50 MPa) and a coefficient of va riation of 0.326. Normalizing the mean of the hammer-drilled series with the mean of the baseline series yields a ratio of 0.826

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33 times the baseline series bond stress. Anchors were also tested for edge effects in the second installation. The average bond stress fo r anchors installed in core-drilled holes 7.5 inches away from one edge was 1350 psi (9. 30 MPa) with a coefficient of variation of 0.099. Normalizing the mean of the edge dist ance series with the mean of the baseline series yields a ratio of 0.909 times the baseline series bond stress. Baseline anchors, as well as those installe d near one edge, were tested in the third installation. The average bond stre ss for the baseline series of anchors installed in coredrilled holes was 1670 psi (11.5 MPa) with a coefficient of variation of 0.097. Anchors installed in core-drilled holes 4.5 inches aw ay from one edge had an average bond stress of 1220 psi (8.40 MPa) with a coefficient of va riation of 0.086. Normalizing the mean of the edge distance series with the mean of th e baseline series yields a ratio of 0.730 times the baseline series bond stress. Finally, the average bond stress of anchors installed in core-drilled holes 6.0 inches away from one edge was 1380 psi (9.50 MPa) with a coefficient of variation of 0.0700. Normalizing th e mean of the edge distance series with the mean of the baseline series yields a rati o of 0.827 times the baseline series of the bond stress. For further comparison, all 11 baseline test results from the three installations were combined into one database. The average bond stress was 1390 psi (9.60 MPa) with a coefficient of variation of 0.192. Th e coefficient of vari ation is less than 0.200, which generally indicates that the grout product’s behavior is reasonably consistent when repeated in the given application. FDOT Section 937 (FDOT 2002a) limits the coefficient of variation for uniform bond stress to 20%, which serves as a basis for using

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34 this limit for the purposes of this paper. Table 6-2 provides a summary of the tests performed to establish 0 for grout product CA in the current paper. Table 6-2 Summary of baseline single anchor test results Installation # N0 kips (kN) 0 psi (MPa) COV n 1 29.4 (131) 1250 (8.60) 0.046 5 2 35.1 (156) 1490 (10.3) 0.040 3 3 39.3 (175) 1670 (11.5) 0.097 3 All 32.7 (145) 1390 (9.58) 0.192 11 6.3 Group Grouted Anchor Test Results Two sets of quadruple fastener group anchor test series were in stalled and tested. All anchors were installed in core-drilled hole s. All parameters, except anchor spacing, were held constant. Table 6-3 provides a summary of the group test series results. In the first anchor installation, groups of grouted anchors were installed in coredrilled holes with an anchor sp acing of 5 inches. All of the re petitions in this test series experienced a concrete cone br eakout failure. Due to this, an average bond stress could not be calculated. The averag e total tensile failure load wa s 64.1 kips (285 kN) with a coefficient of variation of 0.040. According to the CCD method show n in Equation (2), the predicted strength of the grouted anchor groups with an chor spacing of 5 inches was 69.6 kips. Groups of grouted anchors were also inst alled in core-drilled holes in the third installation. In this test seri es, the anchor spacing was increa sed to 9 inches. All of the repetitions in this test series exhibited a bond failure at the grout/concrete interface. The average total tensile failure load was 104 kips (460 kN) with a coefficient of variation of 0.027. The average bond stress of the anchor group was 1100 psi (7.60 MPa). The predicted strength of the grout ed anchor groups using the diameter of the hole in the

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35 uniform bond stress model was 74.4 kips. This value is conservati ve, and a revision to the critical spacing will be presented in the proposed design model in Chapter 8. Table 6-3 Summary of multiple anchor test results Installation # Tested Effect Group in Series f'c at test psi (MPa) Failure Modea Ntest kips (kN) 0,test psi (MPa) 1 G 5.0 1 7670 (52.9) cone 63.4 (282) NA 1 G 5.0 2 7670 (52.9) cone 66.9 (298) NA 1 G 5.0 3 7670 (52.9) cone 62.0 (276) NA N 64.1 (285) COV 0.040 3 G 9.0 1 7330 (50.5) g/c 105 (465) 1110 (7.65) 3 G 9.0 2 7330 (50.5) g/c 106 (469) 1119 (7.72) 3 G 9.0 3 7330 (50.5) g/c 100 (446) 1065 (7.34) N 104 (460) COV 0.027 a Tests in which a failure at the grout/concrete interface occurred are designated as g/c.

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36 CHAPTER 7 TESTED FACTORS INFLUENCI NG GROUT BOND STRENGTH 7.1 General Grouted anchor performance can be infl uenced by a wide variety of factors ranging from grout properties, to installation conditions, to loading and environmental conditions while in-service. It is important to understa nd the effects that various conditions have on grout bond strength to enable proper design of a structure. Testing of a variety of potential effects were performe d over the course of several grouted anchor testing programs with the purpose of determ ining what types of product approval tests might apply to engineered grout products. The following is a written summary of these results. Graphical representations of these results can be found in Appendix F. 7.2 Strength versus Curing Time Kornreich (2001) performed tests on unheaded threaded rods installed using three different grout products: one polymer (PB) and two cementitious (CA and CG) grouts. Tests were performed at 24 hours, 3 days, 7 days, 14 days, and 28 days. The rate at which the grouts attained thei r full bond strength appeared to be product dependent. However, the polymer based grout product se emed to reach its full bond strength in a shorter time period; product PB appeared to reach full stre ngth after only 24 hours. Grout CG matured to full strength after 7 days, and grout CA did not attain full strength until 14 days after installation. Cu rrently, FM 5-568 (FDOT 2000) onl y requires a short-term cure test for adhesive anchors in wh ich tests are performed at only 24 hours.

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37 7.3 Threaded Rod versus Deformed Reinforcing Bar Zamora (1998) performed tests to inves tigate the potential differences between the grout bond strength of unheaded threaded rods and deformed reinforcing bars. Four cementitious grout products were examined. Three of the four products experienced a lower bond strength when the gr out was installed with a defo rmed reinforcing bar. Two of these showed small decreases; products CB and CF experienced a reduction in bond strength of 9% and 4%, respectively. However, the bond strength of product CD diminished by 27%. The fourth product, CC, showed a 104% increase in bond strength when installed with deformed reinforcing bars. However, this product is no longer marketed for this application and should not be used to draw conclusions. The effect on bond strength appears to be product dependent, and products should be tested to observe if a significant strength variation, defined as over 20% for the purposes of this paper, occurs. This limit on bond strength variation is similar to the limit set forth in ICBO ES AC58 (ICBO ES 2001) for variation between st rengths obtained from testing anchors installed in damp holes a nd in baseline dry holes. 7.4 Threaded Rod versus Smooth Rod Kornreich (2001) compared the bond streng th of grouts for unheaded threaded rods and unheaded smooth rods for both cementitious and polymer grout products. For all three products tested, the bond strength for smooth rods was lower than that for threaded rods. However, the amount of bond strength reduction seemed dependent on the type of grout product installed. Grout produc ts CA and CG experienced an 91% and a 81% reduction in bond strengt h, respectively. The polymer grout product tested, PB, exhibited a 53% decrease in bond strength. All of these reductions in bond strength are

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38 sufficiently large such that it is recommended that unheaded smooth rods should not be relied upon in tension. 7.5 Regular Hex Nut versus Heavy Hex Nut Zamora (1998) performed a test series to examine the possible effects that the use of various types of nuts in headed anchor a pplications have on pu llout resistance. The study found that a difference in pullout resist ances existed depending on the type of nut that was used. The pullout resistance of anchors installed with cementitious grouts decreased when a heavy hex nut was used. Products CA, CB, and CC demonstrated a reduction in pullout resistance of 15%, 19%, and 8%, resp ectively, when installed with a heavy hex nut. Contrastingly, the pullout resistance increased by 10% when anchors were installed using polymer grout product PA and a heavy he x nut instead of a re gular hex nut. Since only one polymer grout product was tested, it is unclear if all polymer grouts behave in a similar manner. When installed with a regular hex nut, products CA, CB, CC, and PA exhibited a coefficient of variation of 0.052, 0.136, 0.070, and 0.066, respectively. Products CA, CB, CC, and PA had a coe fficient of variation of 0.124, 0.150, 0.093, and 0.034, respectively, when a heavy hex nut was used for installation. The change in pullout resistance appears to be dependent on the grout product used. However, when the regular hex nut and heavy hex nut tests are considered in tandem for each product, the coefficients of variation are 0.126, 0.187, 0.086, and 0.058 for products CA, CB, CC, and PA, respectively. These coefficients of variat ion are not significant as they are less than 20%, and, therefore, it seems that it is unnecessa ry to test products using different types of nuts.

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39 7.6 Hole Drilling Technique Two test series comparing headed anc hors installed in hammer-drilled holes to those installed in core-drilled holes were pe rformed in the testing program of the current paper. In one test series, there was essent ially no difference between the bond strength of anchors installed in the two types of holes. When anchors were installed in hammerdrilled holes, the bond strength increased by 3% with a coefficient of variation of 0.012. A subsequent test series examined the same grout product, CA. It was found that the results of anchors installed in hammer-drill ed holes were widely scattered with a coefficient of variation of 0.326, and the av erage bond strength was 17% lower than the bond strength of the baseline an chors installed in core-drilled holes. Combining the results of both test series yi elded a coefficient of varia tion of 0.244. These tests from different installations could be considered to gether since each series was normalized with respect to the baseline se ries of that installation. It is possible that when the holes were hammer-drilled the pores in the concrete became filled with dust from the drilling proces s. The presence of this dust could have prevented the grout product from fully bonding to the concrete even though the cleaning procedures recommended by the manufacturer were performed. This could account for the scatter observed in one of the two installations. It is recommended that tests be performed on cementitious grouts to determine if sensitivity to hole drilling technique exists whenever they are to be installed in holes drilled in a ma nner other than that recommended by the manufacturer. 7.7 Damp Hole Installation This test series consisted of anchors installed in damp holes free of standing water. Zamora (1998) tested three polymer grouts: PA, PB, and PC. Two of the products

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40 had a noticeable bond strength reduction when in stalled in damp holes rather than dry holes. Product PB experienced a 17% st rength reduction, and product PC exhibited a 27% decrease in bond strength. A third pr oduct, PA, experienced a bond strength increase 11%. The effect of a damp hole installation on bond strength seems significant and product dependent. Therefore, polymer grout products should be tested for the effects of this vari able on bond strength. 7.8 Elevated Temperature Anchors installed with polymer grouts ar e believed to be more sensitive to temperature variations than cementitious pr oducts. Zamora (1998) tested two polymer grouts, PA and PB, at elevated temperatures and found a reduction in bond strength of 6% for both products when compared to those te sted at ambient temperature. It appears that the bond strengths of th ese two products are not greatly influenced by elevated temperatures. However, Cook and Konz (2001) perfor med similar elevated temperature sensitivity tests on 15 adhesive products. Of the 15 products tested, ten exhibited a bond strength variation of greater than 20%. Adhesive products consist of two components: a resin and a hardener. Polyme r grouts contain similar components as adhesives with a filler for the additional third component. Sin ce adhesive products are strongly influenced by elevated temperatures and polymer grout products are similar in composition, it is important to test polymer grout products being for sensitivit y to elevated temperature. 7.9 Summary Previous testing programs, as well as the current testing program, have tested the bond strength sensitivity of various grouts to several installation conditions. The effects of strength versus curing time, threaded rod versus deformed reinforcing bar for

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41 cementitious grouts, threaded rod versus smooth bar, varying types of nuts on headed anchors, hole drilling technique for cemen titious grouts, damp hole installation for polymer grouts, and elevated temperature we re tested for polymer grouts. Table 7-1 provides a brief summary of the tested variab le of interest, the type of grout product installed, and a short explanation of the results of testing. Table 7-1 Summary of tested fact ors influencing gr out bond strength Grout Type Test Cementitious Polymer Strength vs. Curing Time Effect appears product dependent; generally slower than polymer One product tested Threaded Rod vs. Deformed Reinforcing Bar Effect appears product dependent Not tested Threaded Rod vs. Smooth Bar Large reduction in bond strength for both products tested Reduction in bond strength; one product tested Regular Hex Nut vs. Heavy Hex Nut Reduction in pullout resistance for heavy hex; amount appears product dependent Increase in pullout resistance for heavy hex; unclear if this is a general pattern for polymer products Hole Drilling Technique Effect is not consistent and results are at times widely scattered Not tested Damp Hole Installation Not tested Effect appears product dependent Elevated Temperature Not tested Reduction in bond strength

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42 CHAPTER 8 DISCUSSION ON DESIGN METHOD FOR GROUTED ANCHORS 8.1 Current Models Previous studies have developed design models for adhesive anchors as well as cast-in-place anchors. Cook et al. (1998) found the uniform bond stress model to be an adequate predictor of adhesive anchor behavi or. Similarly, Fuchs et al. (1995) found that the strength of cast-in-place an chors can be accurately predicted using the CCD method. Equations describing the uniform bond stress model and the CCD method are shown in Chapter 3. Modification factor s can be applied to both models to account for anchors near a free edge or spaced close enough to act as an anchor group. 8.2 Predicted Model for Grouted Anchor Behavior Grouted anchors can experience one of th ree different embedment failure modes: failure at the steel/grout interface, failure at the grout/concrete interfac e, or concrete cone breakout failure. Steel failure may also occur. The embedment failure mode and strength can be predicted from equations that repres ent the behavior of each failure mode. The lowest of these predicted stre ngths indicates the expected fa ilure mode unless this failure mode is prevented by physical constraints of the anchor configuration. For example, failure at the steel/grout interface is not possible if a headed anchor is utilized. As previously mentioned, equations to predict anchor strength when failure occurs from a concrete cone breakout or at the steel/grout interface have undergone extensive testing. Zamora (1998) proposed usin g the hole diameter instead of the anchor diameter in the uniform bond stress model to predict anchor strength when failure occurs

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43 at the grout/concrete interface. This substitution was shown previously in Equation (4). Using the failure load obtained from testing, the bond stress, 0, can be calculated. Anchors in the current test program were designed to exhibit a failure at the grout/concrete interface. It was predicted that the bond strength would correspond to the failure load calculated using the hole diameter in the uniform bond stress model. Therefore, the critical edge di stance was expected to be 8 d0, and the critical spacing between adjacent anchors wa s anticipated to be 16 d0 as shown previously in Figure 3-6. However, Figures 8-1 and 8-2 show that the coefficients of 8 and 16 are overly conservative for predicting the mean anchor bond strength for anchors installed near a free edge and in fastener groups, respectively. Figure 8-1 depicts a plot of the normalized anchor strength versus edge distance. To normalize, the test result and the predictive curve were divided by the predic ted strength of a single anc hor installed away from an edge and surrounding anchors. Figure 8-2 pr esents a graph of the normalized anchor group strength versus anchor spacing. The te st result and predictive curve were divided by four times the predicted stre ngth of a single anchor insta lled away from an edge and surrounding anchors to normalize. Theref ore, the behavior of grouted anchors experiencing a bond failure at the grout/concrete interface can be better represented if the critical edge and spacing distances are revised. The following sections provide recomme nded equations and m odification factors for determining the design strength of si ngle grouted anchors and groups of grouted fasteners in uncracked concrete using Lo ad and Resistance Factor Design (LRFD). 8.3 Proposed Critical Edge Distance a nd Critical Anchor Spacing Revision Different values for the critical edge di stance and anchor spacing were considered by graphically fitting design equa tions to the test data. It was assumed that the critical

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44 024681012 0 0.5 1 1.5 Edge Distance (inches)Normalized Anchor Strength Figure 8-1 Critical edge distance of 8 d0 compared to experimental results 024681012 0 0.2 0.4 0.6 0.8 1 Anchor Spacing (inches)Normalized Anchor Group Strength Figure 8-2 Critical anchor spacing of 16 d0 compared to experimental results anchor spacing is twice the cr itical edge distance, simila r to the existing uniform bond stress model. The values chosen to best f it the experimental data of the current paper’s Equation (6) with single anchor Equation (6) with anchor group

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45 test program were 5 d0 for the critical edge distance and 10 d0 for the critical spacing between anchors. Figures 8-3 and 8-4 di splay how these new coefficients more accurately predict the mean failure loads obt ained during testing and are normalized as discussed in the previous s ection for Figures 8-1 and 8-2. In Figure 8-4, the proposed equation predicts a higher strength for bond fa ilure at the grout/concrete interface than that found from testing when th e anchor spacing equals 5 inches. This was as expected since the failure mode observed during te sting was a concrete cone breakout which occurred at a lower load than a failure at the grout/concrete interface. 024681012 0 0.5 1 1.5 Edge Distance (inches)Normalized Anchor Strength Figure 8-3 Critical edge distance of 5 d0 compared to experimental results 8.4 Proposed Model for Single Grouted Anchors For single unheaded grouted anchors, it is recommended that the design strength be taken as the smaller of the bond strengths ca lculated at the steel/grout interface and at the grout/concrete interface using Equation (9) and Equation (10), respectively. The following design equations are based on the uni form bond stress model and a 5% fractile.

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46 024681012 0 0.2 0.4 0.6 0.8 1 Anchor Spacing (inches)Normalized Anchor Group Strength Figure 8-4 Critical anchor spacing of 10 d0 compared to experimental results ) ( ', 0 ef e b bh d N (lbf or N) (9) ) ' ( '0 0 0 ,0 0ef e b bh d N (lbf or N) where 0 ,5 3 0 7 0 '0d ce (10) For single headed grouted anchors, it is recommended that the design strength be taken as the smaller of the bond strength calcu lated at the grout/concre te interface and the concrete cone breakout strength using Equations (10) and (11a or 11b), respectively. The following design equations are based on the CCD model and a 5% fractile. ) 30 ( '5 1 0 ef c e c c c ch f N (lbf) (11a) or

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47 ) 6 12 ( '5 1 0 ef c e c c c ch f N (N) (11b) 8.5 Proposed Design Model for Grouted Anchor Groups For groups of unheaded grouted fastener s, it is recommended that the design strength be taken as the smaller of the bond strengths calculated at the steel/grout interface and at the grout/concrete interface usin g Equations (12) and (13), respectively. The following design equations are based on the uniform bond stress model and a 5% fractile. ) ` ( '0 0 N A A NN N b b (lbf or N) (12) ) ` ( '0 00 0 N A A NN N b b (lbf or N) (13) For groups of headed grouted anchors, it is recommended that the design strength be taken as the smaller of the bond strength ca lculated at the grout/c oncrete interface and the concrete cone breakout strength using E quations (13) and (14), respectively. The following design equation is based on the CCD model and a 5% fractile. ) ( '0 0 c N N c cone cN A A N (lbf or N) (14) In Equations (12 and 14), AN and AN0 are calculated as shown in Figures 3-4 and 3-2, respectively. In Equation (13), AN and AN0 are calculated as show n in Figure 3-6 except using a critical edge distance of 5 d0 and a critical anchor spacing of 10 d0.

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48 CHAPTER 9 DISCUSSION ON PROPOSED PRODUCT APPROVAL TESTS 9.1 General A good grout product will possess th e following desirable qualities: flowability for ease of placement and sufficient working time low sensitivity to hole drilling technique low sensitivity to hole cleaning technique low sensitivity to moisture condition of hole low sensitivity to temperature differentials rapid development of bond strength consistent bond strength when in stalled using various types of anchors The following sections present the proposed product approval tests to evaluate engineered grout products. In all of the fo llowing, the maximum coefficient of variation is limited to 20% unless otherwise stated by th e Engineer for the given application. This is similar to the aforementioned limit placed on the coefficient of variation for uniform bond stress in FDOT Section 937 (FDOT 2002a) fo r adhesives. As mentioned in Section 7.3, the level that constitutes a significan t change in bond strength is 20% for the purposes of this paper. Additi onally, in all sections a minimum of five repetitions should be performed in accordance with ASTM E 488 (ASTM 2001d). When only steel failure occurs, ASTM E 488 requires a minimum of three repetitions.

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49 9.2 Grout/Concrete Bond Stress ( 0) This proposed product approval test a llows the grout/concrete bond stress ( 0) to be determined for a given grout product. Th is value can be calculated from the anchor strength if a bond failure occurs at the gr out/concrete interface. Failure at the grout/concrete interface is a failure mode that occurs infrequently, but test parameters can be configured to force this failure mode to o ccur. This failure mode can be achieved by using a headed anchor to preclude failure at the steel/grout interface and minimizing the hole diameter. Additionally, a bond failure at the grout/concrete interface can be achieved by using a higher strengt h concrete such that the tensile capacity associated with a grout/concrete bond failure will be less than th e breakout capacity of the concrete. All anchors shall be installed per manufacturer in structions using a 0.75 in ch diameter anchor headed with a heavy hex nut and installed in a 1.5 inch diameter hole with an embedment length of 5 inches measured from the top of the nut. Once 0 is determined for a grout product, it can be used in calculations for predicting the strength of various anchor configurations such as edge distance and group tests. 9.3 Test Series to Establish Steel/Grout Bond Stress ( This test series allows the steel/grout bond stress ( to be determined for a given grout product. This value can be calculated fr om the bond strength if a failure is forced at the steel/grout interface. This failure mode can be initia ted by using unheaded anchors installed in concrete whose breakout capacity is greater th an the bond capacity of the grout product. All anchors sh all be installed in accordan ce with the manufacturer’s instructions and as unheaded to promote a failu re at the steel/grout interface. All anchors shall be installed per manufacturer instru ctions using a 0.75 inch diameter unheaded

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50 anchor installed in a 1.5 inch diameter hol e with an embedment length of 5 inches measured from the base of the anchor. Once has been determined for a grout product, it can be used in subsequent st rength prediction calculations. 9.4 Strength versus Curing Time In certain scenarios, it may be necessary for an anchor to sustain loading a short time after installation. It is advantageous to know when a product develops sufficient strength so that premature loading, and the resulting problems, may be avoided. In the same vein, construction time may be saved if it is known that a part icular grout product achieves sufficient strength in a short amount of time. Anchors shall be installed according to manufacturer directions and as unheaded. Polymer grouted and quick setting cementitious grouted anchors should be tested at 24 hours and 7 days. Non-quick setting cementitious grouted anchors should be tested at 7 days and 28 days. A minimum of five anchors should be tested at each interval. The interval at which the bond st rength reaches a sufficient value should be noted. This knowledge can be used in construction schedulin g as well as in choosing a grout product whose strength development fits into a given time frame. 9.5 Threaded Rod versus Deformed Reinforcing Bar It is important to compare the bond strength a grout product possesses for threaded rods and deformed reinforcing ba rs. Both of these materials are commonly installed in the field, so being able to pred ict how they will behave while in-service is imperative. This test program should inve stigate the performance of unheaded grouted anchors installed with a threaded rod and comp are this behavior to that when a deformed reinforcing bar is installed. Installation using a threaded r od shall be considered as the baseline series. Unheaded anchors must be used to try to force a fail ure at the steel/grout

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51 interface. A failure at this location will allow calculation of the bond stress, directly from the bond strength. All anchors shall be installed in accord ance with the manufac turer’s directions and as unheaded. The resulting bond strength s should be compared. Ideally, the grout product would exhibit similar bond strengths for both types of anchors. The results from testing of threaded rods and reinforcing bars should be compared. If the deformed reinforcing bar average bond strength is mo re than 20% less than the average bond strength of threaded rods, or if the coefficien t of variation of the deformed reinforcing bar test series exceeds the aforementioned maximu m, the grout product should be limited to installation with threaded rods. 9.6 Hole Drilling Technique Anchor test series should include the baseline series of installing headed anchors in core-drilled holes according to the manufact urer’s directions as well as a series of headed anchors installed per manufacturer inst ructions except in holes drilled with the hole drilling technique to be evaluated. In orde r to evaluate the effect of the hole drilling technique, a bond failure at the grout/concrete interface must occur. Therefore, all anchors shall be installed using the type of nut, anchor diameter, hole diameter, and embedment depth described in S ection 9.2. If either the coef ficient of variation for the tested hole drilling technique or the reduction in the bond strength between the baseline and the variable test series exceed the limit of 20%, the grout product tested should not be installed in holes drilled using th e tested hole drilling technique. 9.7 Moisture Condition of Hole Bond strength can be influenced by th e moisture condition of the hole depending on the type of grout product used for anc hor installation. Cementitious grout products

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52 commonly require installation in damp holes to prevent excessive water loss from the grout to the concrete, which could reduce the bond strength of the gr out. Polymer grouts are usually installed in dry holes to allow th e chemical reactions to occur, thus binding the grout to the concrete. If a polymer grouted anchor is installed in a damp hole (i.e. a core-drilled hole that has not been given su fficient time to dry), the presence of water could impede the bonding process, thus reducing the bond strength. Grout products being evaluated should be tested for sensitivit y to damp or dry hole conditions. In order to evaluate the effect of the moisture conditi on of the hole, it is necessary for failure to occur at the grout/concrete inte rface. Therefore, all anchors shall be installed using the type of nut, anchor diameter hole diameter, and embedmen t depth described in Section 9.2. In the damp hole installation test seri es, polymer grouted anchors should be installed as headed and according to the ma nufacturer’s instructions, except the holes shall be damp at the time of installation as described in Section 5.3. Additionally, a baseline series needs to be installed as pe r manufacturer instructions. The bond strength from the baseline series and the damp hole in stallation series should be compared. ICBO ES AC58 (ICBO ES 2001) states that all dampness specimen results shall be at least 80% of the average of the baseline specimens. Th e appropriate restrictio ns, if any, should be assigned to the polymer grout product base d on the bond strength re sults evaluated in accordance with ICBO ES AC58 and the maximum coefficient of variation as set forth in this paper. In the dry hole installation test series, cementitious grouted anchors should be installed in accordance with the manufacturer ’s instructions, except the holes shall be dry

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53 at the time of installation. Additionally, a baseline series needs to be installed per manufacturer instructions. The bond strength from the baseline series and the dry hole installation series should be compared. Dry specimen shall be considered in a similar manner to dampness specimen. All dry hole insta llation specimen results shall be at least 80% of the average of the baseline series. The coefficient of vari ation of the dry hole installation series shall be less than the aforementioned maximum. The appropriate restrictions, if any, should be assigned to the cementitious grout product based on the bond strength results. 9.8 Elevated Temperature This parameter is considered more criti cal for polymer grouts as they are believed to be more sensitive to temperature changes. Test series of headed and unheaded anchors installed, cured, and tested at elevated temperature (110 F; 43.3 C) should be performed. The anchors should be installed in accordance with the manufacturer’s directions, except at elevated temperature. The bond strengths from each series should then be compared. The grout product may be approved for use in elevated temperature applications if the average bond strength at elevated temperature is not more than 20% less than the bond strength of the baseline series and the coefficient of variation of the elevated temperature series is less than the limit set forth in this paper. 9.9 Horizontal and Overhead Hole Orientation (Optional) Bond strength has the pote ntial to be significantly reduced when anchors are installed at an orientation other than verti cally downward. This reduction is due to the grout settling unevenly or flow ing out of the hole. For a horizontal installation, the anchor is perpendicular to the vertical face of the concrete. The anc hor potentially settles against the lower surface of the hole resulting in a nonuniform grout thickness around

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54 the anchor. Additionally, air voids can form along the upper hole surface. This diminishes the bond area and thus results in a corresponding reduction in bond strength. For an overhead orientation, the anchor is installed vertically upward. The grout wants to flow out of the hole, and the anchor potentially settles in an outward movement. This settlement can result in a reducti on in the effective embedment depth and corresponding losses of bond area and bond strength. In order to minimize the punitive effects an alternate hole orientation can have on bond strength, it is highly recommended that cem entitious grouts should not be installed in this type of application. Non-quick se tting cementitious grouts are not sufficiently viscous, and their initial set time is too long to make their use pract ical for alternate hole orientation installations. Similarly, polymer grouts possessing low viscosities should also not be utilized. In the optional horizontal hole orientati on test series, grouted anchors shall be installed in accordance with manufacturer directions, excep t in horizontally oriented holes. The bond strength from the baseline series installed in vertical holes and horizontal hole orientation series should be compared. If the bond strength is reduced by more than the limit set forth in this paper when installed horizontally, or if the coefficient of the horizontal hole test series exceeds the aforementioned maximum, the grout product shall be excluded from installation in horizontally oriented holes. Similar optional tests to those perfor med on anchors in th e horizontal hole orientation test series shoul d be performed on grouted anchors installed in overhead holes. This test series should also be compared to the baseline series. Similarly, if the reduction in bond strength or the coefficient of variation of the ove rhead test series

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55 exceed the limits set forth in this paper, th e grout product shall be excluded from use in this application. 9.10 Long-term Load (Optional) Anchors subjected to sustained tension loading may undergo displacements due to creep. If the rate of displacement does not attenuate, the anchor displacement will reach unacceptable levels. The variable of interest is the amount of displacement. Therefore, the applied load should not induce failure. The applied load shoul d be a service level load that can be taken as a pe rcentage of the tensile load that incites failure. Similar to FM 5-568 (FDOT 2000), it is recommended that a tensile load that is 40% of the mean failure load value from the baseline series be used. This test series is optiona l unless sustained long-term lo ad is anticipated. Both headed and unheaded anchors shall be tested. In these test series, anchors should be installed per the manufacturer’s directions. In accordance with FM 5-568, creep tests shall be performed at elevated temperature. Displacements should be measured more frequently near the beginning of the loading period. It is recommended that di splacement data should be sampled for a minimum of 42 days. At the end of 42 days, th e load can be removed from the anchors. In accordance with FDOT Section 937 (FDOT 2002a), the rate of displacement shall decrease during the 42 day loading period. Al so, at the end of the loading period, the total creep displacement shall be less than 0.03 inch (0.75 mm) and less than 0.003 inch (0.075 mm) during the last 14 days of loading. The anchors that have not exceeded the pr edefined displacement limit should then be reloaded in tension and tested to failure. The bond st rength from these reloaded anchors should be compared to that of the baseline test series. If the coefficient of

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56 variation or the reduction in bond strength of the creep test series exceed the limits set forth in this paper, it may be appropriate to limit the use of the produc t to applications in which service loads would not need to be su stained long-term. If the level of creep displacement exceeds the limit, the anchor can be considered to have failed. 9.11 Additional Factors Other factors may also need to be cons idered when determining whether a grout product can be used in a certain application. Some additional factors are: repeated loads, freezing and thawing cycles, seismic (shear a nd tension), cracked concrete, and concrete aggregate. Testing methods for these fact ors are outside the scope of this report.

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57 CHAPTER 10 SUMMARY, CONCLUSIONS, AND RECOMMENDATIONS 10.1 Summary This thesis addresses the behavior of headed and unheaded grouted anchors installed in uncracked concrete tested in tensi on. Data from this test program as well as a summary of data from other test programs ar e presented. A variety of products, anchor configurations, installation conditions, edge distances, and group anchor spacings have been tested. Test results were used to establish if existing behavioral models for adhesive and cast-in-place anchors could be extended to accurately predict the strength of grouted anchors. These models are the uniform bond stress model and the concrete capacity design model, respectively. Additionally, factors that constitute a desirable grout product are discussed. The results from various in stallation and service condition tests are analyzed, and product approval tests for grouts are proposed. 10.2 Conclusions Grouted anchor behavior varies depe nding on the product used for installation, whether the anchor is installed as unheaded or headed, installed near an edge, installed in an anchor group, and what installation and se rvice conditions the anchor is exposed to. Four different failure modes exist for grouted anchors: bond failure at the steel/grout interface, bond failure at the grout/concrete in terface, concrete breakout failure, and steel failure. Ignoring steel failure, unheaded gr outed anchors predominantly experience a bond failure at the steel/grout in terface, but a bond failure at the grout/concrete interface has also been observed. Again, ignoring st eel failure, headed grouted anchors may

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58 experience either a bond failure at the grout /concrete interface or a concrete cone breakout. In general, the capacity of unheaded gr outed anchors can be predicted by the uniform bond stress model (Equations (3) a nd (5)), which is based on the bond stress ( ) at the steel/grout inte rface. If the grout/concrete bond stress ( 0) is low enough, a bond failure may occur at the grout concrete in terface (Equations (4) and (6)). The failure mode can be predicted based on which equa tion yields the smaller bond strength. For design, the expected anchor strength can be taken as th e lesser of Equation (9) and Equation (10). Bond failure at the steel/gr out interface is pr ecluded for headed grouted anchors by the presence of the head. The capacity of headed grouted anchors can be predicted by either the uniform bond stress model (Equations (4) and (6)) or the concrete capacity design model (Equations (1a or 1b) and (2)). The failure mode can be predicted by which of these two models yields the lower result. For design, the expected anchor strength can be taken as the lesser of Equation (10) and Equations (11a or 11b). The test program reported in this thesis indicated that the critical edge distance and critical anchor spacing of the uniform bond stress model currently used for adhesive anchors were not accurate for grouted anchors. The data were analyz ed, and the critical edge distance for grouted anchors was found to be 5 d0; the critical anchor spacing for grouted anchors was found to be 10 d0. This report includes an analysis of test s of installation and service conditions. The tests performed in the current test program and in previous testing programs led to the following conclusions:

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59 Products develop strength at differe nt rates. In general, polymer grouts develop a significant portion of strength more rapidly than cementitious grouts. The type of grout product used to install the anc hor can greatly influence the anchor strength. Unheaded smooth rods should not be relied upon in tension. Headed grouted anchors are not sensitive to the type of nut (regular hex or heavy hex) used on the embedded end during installation. The moisture condition of the hol e affects the bond strength of anchors installed with polymer grout s, and it is conjectured that cementitious grouts can also be sensitive to the moisture condition of the hole. Polymer grouts are believed to be sensitive to elevated temperatures since they are simila r in composition to adhesives, which have been shown to possess this sensitivity. 10.3 Recommendations Based on the test results presented in this thesis, the following tests are proposed to establish grout product properties and sensitivities: Establish 0. Establish Establish strength development curve. Compare threaded rod versus deformed reinforcing bar. Evaluate sensitivity to hole drilling technique.

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60 Evaluate sensitivity to moisture condition of hole. Evaluate sensitivity to elevated temperature. Additionally, hole orientation and long-term loading (creep ) tests are proposed as optional tests. A comprehensive design model for gr outed anchors is needed, and the CCD method and modifications to the uniform bond stress model were shown to accurately predict anchor capacity. It was observed that installati on and service conditions will affect the behavior of grouted anchors, a nd product approval tests were proposed to investigate some of these effects. Further testing is recommended to establish safety factors for the aforementioned installation and service conditions. Future study is recommended for the following topics not addressed in this paper: The effect of repeated loads on the performance of grouted anchors. The effect of freezing and thawi ng cycles on the performance of grouted anchors. The effects of seismic forces (shear and tension) on the performance of grouted anchors. The effect of cracked concrete members on the performance of grouted anchors. The effect of various concrete aggregates on the performance of grouted anchors.

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61 APPENDIX A NOTATION c = distance from center of an anchor shaft to the edge of concrete, in (mm). c1 = distance from the center of an anchor shaft to the edge of concrete in one direction, in (mm). c2 = distance from the center of an anchor shaft to the edge of concrete in the direction orthogonal to c1, in (mm). d = diameter of the anchor, in (mm). d0 = diameter of the hole, in (mm). di = net potentiometer displacement; subscript ranges from 1 to 4 for quadruple fastener anchor groups, in (mm). dn = distance from the surface of the conc rete to the bottom of the pull plate at each anchor in an anchor group; subscript ranges from 1 to 4 for quadruple fastener anchor groups, in (mm). dn,poten = distance from the surface of the conc rete to the bottom of the pull plate at each potentiometer in an anchor group; subscript ranges from 1 to 4 for quadruple fastener anchor groups, in (mm). dtot = overall displacement of an anchor group, in (mm). f’c = concrete compressive strength, psi (N/mm2). hef = effective anchor embedment depth, in (mm). k = factor based on a 5% fractile, 90% confidence, and number of tests performed. n = number of tests performed. s = anchor center-to-center spacing, in (mm). s1 = anchor center-to-center sp acing in one dire ction, in (mm).

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62 s2 = anchor center-to-center sp acing in the dir ection orthogonal to s1, in (mm). Abond = bonded surface area between grout and concrete, in2 (mm2). AN = projected concrete failure area of an anchor or group of anchors, for calculation of strength in tension, in2 (mm2). AN0 = projected concrete failure area of one anchor, for calculation of strength in tension when not lim ited by edge distance or spacing, in2 (mm2). N = general mean tensile strength for an anchor group with unspecified failure mode, lbf (N). N0 = general mean tensile strength for a single anchor with unspecified failure mode, lbf (N). Nc,0 = mean tensile strength for concrete c one breakout of a single anchor, lbf (N). N ,0 = mean tensile strength for steel/grout failure of a single anchor, lbf (N). N 0,0 = mean tensile strength for grout/conc rete failure of a single anchor, lbf (N). Nc = mean tensile strength for concrete cone breakout of an anchor group, lbf (N). Ntest = tensile strength of a single anchor or an anchor group for one test repetition, lbf (N). N = mean tensile strength for steel/gr out failure of an anchor group, lbf (N). N 0 = mean tensile strength for grout/conc rete failure of an anchor group, lbf (N). N’c,0 = nominal tensile strength for concrete cone breakout of a single anchor, lbf (N). N’ ,0 = nominal tensile strength for steel/ grout failure of a single anchor, lbf (N). N’ 0,0 = nominal tensile strength for grout/conc rete failure of a single anchor, lbf (N). N’cone = nominal tensile strength for concre te cone breakout of an anchor group, lbf (N). N’ = nominal tensile strength for steel/ grout failure of an anchor group, lbf (N). N’ 0 = nominal tensile strength for grout/c oncrete failure of an anchor group, lbf (N). COV = coefficient of variation.

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63 b = strength reduction factor fo r bond failure (0.85 is recommended). c = strength reduction factor for conc rete cone breakout (0.75 is recommended). = mean uniform bond stress at the steel/grout interface, psi (MPa). 0 = mean uniform bond stress at th e grout/concrete inte rface, psi (MPa). 0,test = uniform bond stress at the grout/conc rete interface for a single anchor or an anchor group in one test repetition, psi (MPa). ’ = (1-kCOV) nominal uniform bond stress at the steel/grout interface, psi (MPa). ’0 = 0(1-kCOV) nominal uniform bond stress at the grout/concrete interface, psi (MPa). ,e = modification factor, for strength in tension, to account for edge distances when bond failure occurs at the steel/grout interface. 0,e = modification factor, for strength in tension, to account for edge distances when bond failure occurs at the grout/concrete interface. c,e = modification factor, for strength in tension, to account for edge distances when concrete cone breakout failure occurs.

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64 APPENDIX B TENSILE LOAD VS. DISPLACEMENT GRAPHS FOR BASELINE AND HOLE DRILLING TECHNIQUE TEST SERIES This appendix contains the results from testing of single anchors installed away from an edge. Table B-1 lists the detail s about each test performed including the installation number, the effect being tested, the anchor number in the given test series, the average concrete compressive stress at the time of testing, the failure mode, the tensile strength of the anchor, and the bond stress of the anchor. Figures B-1 through B-5 depict the axial tensile load versus the vertical di splacement for the various tests performed. The title of each graph within the figures denotes information about the test being performed. The first two letters in the title sp ecify the type of hole drilled. Core-drilled holes are represented by CD, a nd hammer-drilled holes are represented by HD. The first number identifies the test series of the hole type. The second number identifies the individual anchor in the series.

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65 Table B-1 Individual baseline and hole dr illing technique anchor test results Installation # Tested Effect Anchor in Series f'c at test psi (MPa) Failure Mode Ntest kips (kN) 0,test psi (MPa) 1 Baseline 1 6600 (45.5) g/c 27.6 (123) 1170 (8.07) 1 Baseline 2 6600 (45.5) g/c 30.2 (134) 1280 (8.84) 1 Baseline 3 6680 (46.1) g/c 28.67 (127) 1220 (8.39) 1 Baseline 4 6680 (46.1) g/c 29.2 (130) 1240 (8.54) 1 Baseline 5 6680 (46.1) g/c 31.1 (138) 1320 (9.09) 1 Hammer 1 6600 (45.5) g/c 30.0 (134) 1280 (8.79) 1 Hammer 2 6600 (45.5) steel 26.1 (116) NA 1 Hammer 3 6680 (46.1) g/c 30.6 (136) 1300 (8.94) 1 Hammer 4 6680 (46.1) steel 24.4 (109) NA 1 Hammer 5 6680 (46.1) steel 24.1 (107) NA 2 Baseline 1 7200 (49.6) g/c 35.8 (159) 1520 (10.5) 2 Baseline 2 7200 (49.6) g/c 36.1 (160) 1530 (10.6) 2 Baseline 3 7200 (49.6) g/c 33.5 (149) 1420 (9.80) 2 Hammer 1 7200 (49.6) g/c 38.9 (173) 1650 (11.4) 2 Hammer 2 7200 (49.6) g/c 20.0 (89.2) 851 (5.86) 2 Hammer 3 7200 (49.6) g/c 28.0 (125) 1190 (8.19) 3 Baseline 1 7330 (50.5) g/c 41.7 (186) 1770 (12.2) 3 Baseline 2 7330 (50.5) g/c 41.3 (184) 1750 (12.1) 3 Baseline 3 7330 (50.5) g/c 34.9 (155) 1480 (10.2)

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66 Figure B-1 Graphs of test results of first installation of core-d rilled anchors A) First test in series; B) Second test in seri es; C) Third test in series; D) Fourth test in series; E) Fifth test in series; F) Comparison of all test in series (a)(b) (c)(d) CD 1-1 27.56970 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips CD 1-2 30.189090 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips CD 1-3 28.657260 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips CD 1-4 29.186510 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips (e)(f) CD 1-1, CD 1-2, CD 1-3, CD 1-4, CD 1-50 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips CD 1-5 31.072450 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips A) B) C) D) F) E)

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67 Figure B-2 Graphs of test resu lts of second installation of co re-drilled anchors A) First test in series; B) Second test in series; C) Third test in series; D) Compar ison of all test in series (a)(b) (c)(d) CD 2-1 35.764720 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips CD 2-1, CD 2-2, CD 2-3 0 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips CD 2-2 36.049530 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips CD 2-3 33.491850 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips A) B) C) D)

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68 Figure B-3 Graphs of test results of third installati on of core-drilled an chors A) First test in series; B) Second test in se ries; C) Third test in series; D) Comparison of all test in series (a)(b) (c)(d) CD 3-1 41.740990 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips CD 3-1, CD 3-2, CD 3-3 0 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips CD 3-2 41.308840 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips CD 3-3 34.935430 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips A) B) C) D)

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69 Figure B-4 Graphs of test resu lts of first installation of ha mmer-drilled anchors A) First test in series; B) Second test in series; C) Third test in series; D) Fourth test in series; E) Fifth test in series; F) Comparison of all test in series (a)(b) (c)(d) HD 1-1 30.041090 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips HD 1-2 Steel Broke 26.079540 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips HD 1-3 30.55210 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips HD 1-4 Steel Broke 24.41320 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips (e)(f) HD 1-1, HD 1-2, HD 1-3, HD 1-4, HD 1-50 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips HD 1-5 Steel Broke 24.049690 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips A) B) C) D) F) E)

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70 Figure B-5 Graphs of test re sults of second installation of hammer-drilled anchors A) First test in series; B) S econd test in series; C) Third te st in series; D) Comparison of all test in series (a)(b) (c)(d) HD 2-1 38.86170 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips HD 2-1, HD 2-2, HD 2-3 0 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips HD 2-2 20.044010 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips HD 2-3 27.989950 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips B) C) D) A)

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71 APPENDIX C TENSILE LOAD VS. DISPLACEMENT GRAPHS FOR EDGE DISTANCE TEST SERIES This appendix contains the results from testing of single anchors installed near one edge. Table C-1 lists the details about each test performed including the installation number, the effect being teste d, the anchor number in the given test series, the average concrete compressive stress at th e time of testing, the failure mode, the tensile strength of the anchor, and the bond stress of the anchor Figures C-1 through C-3 depict the axial tensile load versus the vertical displacement for the various tests performed. The title of each graph within the figures denotes inform ation about the test being performed. The first letter in the title specifies that an e dge test is being performed. The first number identifies the edge distance of the test series The second number identifies the individual anchor in the series.

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72 Table C-1 Individual edge distance anchor test results Installation # Tested Effect Anchor in Series f'c at test psi (MPa) Failure Mode Ntest kips (kN) 0,test psi (MPa) 2 Edge 7.5 1 6460 (44.5) g/c 29.7 (132) 1260 (8.70) 2 Edge 7.5 2 6460 (44.5) g/c 31.95 (142.14) 1360 (9.35) 2 Edge 7.5 3 6460 (44.5) g/c 36.5 (162) 1550 (10.7) 2 Edge 7.5 4 6460 (44.5) g/c 33.1 (147) 1400 (9.67) 2 Edge 7.5 5 6460 (44.5) g/c 28.3 (126) 1200 (8.29) 3 Edge 4.5 1 7600 (52.4) g/c 32.2 (143) 1370 (9.42) 3 Edge 4.5 2 7600 (52.4) g/c 28.2 (126) 1200 (8.26) 3 Edge 4.5 3 7600 (52.4) g/c 30.1 (134) 1280 (8.80) 3 Edge 4.5 4 7600 (52.4) g/c 26.7 (119) 1130 (7.81) 3 Edge 4.5 5 7600 (52.4) g/c 26.3 (117) 1110 (7.68) 3 Edge 6.0 1 7330 (50.5) g/c 36.2 (161) 1540 (10.6) 3 Edge 6.0 2 7330 (50.5) g/c 30.9 (137) 1310 (9.04) 3 Edge 6.0 3 7330 (50.5) g/c 32.6 (145) 1390 (9.55) 3 Edge 6.0 4 7330 (50.5) g/c 32.3 (144) 1370 (9.45) 3 Edge 6.0 5 7330 (50.5) g/c 30.4 (135) 1290 (8.90)

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73 Figure C-1 Graphs of test results of core-d rilled anchors installed 4.5 inches away from one edge A) First test in series ; B) Second test in series; C) Th ird test in series; D) Fourth test in series; E) Fifth test in series; F) Comparison of all test in series (a)(b) (c)(d) E 4.5-1 32.18530 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips E 4.5-2 28.225710 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips E 4.5-3 30.081610 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips E 4.5-4 26.698520 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips (e)(f) E 4.5-1, E 4.5-2, E 4.5-3, E 4.5-4, E 4.5-5 0 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips E 4.5-5 26.2490 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips B) C) D) F) E) A)

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74 Figure C-2 Graphs of test results of core-d rilled anchors installed 6.0 inches away from one edge A) First test in series ; B) Second test in series; C) Th ird test in series; D) Fourth test in series; E) Fifth test in series; F) Comparison of all test in series (a)(b) (c)(d) E 6.0-1 36.231660 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips E 6.0-2 30.89360 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips E 6.0-3 32.638690 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips E 6.0-4 32.294470 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips (e)(f) E 6.0-1, E 6.0-2, E 6.0-3, E 6.0-4, E 6.0-5 0 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips E 6.0-5 30.419990 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips A) B) C) D) F) E)

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75 Figure C-3 Graphs of test results of core-d rilled anchors installed 7.5 inches away from one edge A) First test in series ; B) Second test in series; C) Th ird test in series; D) Fourth test in series; E) Fifth test in series; F) Comparison of all test in series (e)(f) E 7.5-1, E 7.5-2, E 7.5-3, E 7.5-4, E 7.5-5 0 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips E 7.5-5 28.329580 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips (a)(b) (c)(d) E 7.5-1 29.737660 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips E 7.5-2 31.953680 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips E 7.5-3 36.47250 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips E 7.5-4 33.050690 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips A) B) C) D) F) E)

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76 APPENDIX D TENSILE LOAD VS. DISPLACEMENT GRAPHS FOR GROUP TEST SERIES This appendix contains the results from te sting of anchor groups. Table D-1 lists the details about each test pe rformed including the installation number, the effect being tested, the group number in the given test seri es, the average concrete compressive stress at the time of testing, the failure mode, the anchor number in the given test series, the tensile strengths of the individual anchor s as well as the anchor group, and the bond stresses of the individual anchors and the anchor group. Figures D-1 through D-6 depict the axial tensile load versus the vertical di splacement for the various tests performed. The title of each graph within the figures denotes information about the test being performed. The first letter in the title speci fies that a group test is being conducted. The first number identifies the anchor spacing of the test series. The second number identifies the group in a series. The remaining letters specify the load measuring instrument being used. The load washer on each anchor is re presented by LW, and the overall load cell for the anchor group is represented by OLC. The third number identifies the individual anchor on which data is being measured.

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77 Table D-1 Individual group anchor test results Installation # Tested Effect Group in Series f'c at test psi (MPa) Failure Mode Anchor Ntest kips (kN) 0,test psi (MPa) 1 Error NA 2 13.7 (61.1) NA 3 15.2 (67.5) NA 4 13.2 (58.5) NA 1 G 5.0 1 7670 (52.9) cone All 63.4 (282) NA 1 Error NA 2 13.8 (61.2) NA 3 16.1 (71.8) NA 4 16.2 (72.1) NA 1 G 5.0 2 7670 (52.9) cone All 66.9 (298) NA 1 Error NA 2 16.7 (74.1) NA 3 13.67 (60.8) NA 4 15.0 (66.6) NA 1 G 5.0 3 7670 (52.9) cone All 62.0 (276) NA 1 Error Error 2 27.5 (122) 1170 (8.05) 3 28.6 (127) 1210 (8.37) 4 25.3 (112) 1070 (7.39) 3 G 9.0 1 7330 (50.5) g/c All 105 (465) 1110 (7.65) 1 Error Error 2 22.2 (98.7) 942 (6.49) 3 24.3 (108) 1030 (7.10) 4 32.7 (145) 1390 (9.57) 3 G 9.0 2 7330 (50.5) g/c All 106 (469) 1120 (7.72) 1 Error Error 2 21.1 (93.7) 894 (6.16) 3 23.4 (104) 991 (6.83) 4 25.5 (114) 1080 (7.47) 3 G 9.0 3 7330 (50.5) g/c All 100 (446) 1070 (7.34)

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78 Figure D-1 Graphs of results of first core-d rilled anchor group installed with anchor spacing of 5.0 inches A) Load on first anc hor; B) Load on second anchor; C) Load on third anchor; D) Load on fourth anchor; E) Comparison of all anchor loads in test; F) Load on entire anchor group (a)(b) (c)(d) G 5-1 LW 1Instrument Malfunction0 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips G 5-1 LW 2 13.726620 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips G 5-1 LW 3 15.178560 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips G 5-1 LW 4 13.161290 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips (e)(f) G 5-1 LW 1-4 0 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips G 5-1 OLC 63.350370 10 20 30 40 50 60 70 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips A) B) C) D) F) E)

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79 Figure D-2 Graphs of results of second core-d rilled anchor group in stalled with anchor spacing of 5.0 inches A) Load on first anc hor; B) Load on second anchor; C) Load on third anchor; D) Load on fourth anchor; E) Comparison of all anchor loads in test; F) Load on entire anchor group (a)(b) (c)(d) G 5-2 LW 1Instrument Malfunction0 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips G 5-2 LW 2 13.755450 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips G 5-2 LW 3 16.135720 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips G 5-2 LW 4 16.196540 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips (e)(f) G 5-2 LW 1-4 0 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips G 5-2 OLC 66.927940 10 20 30 40 50 60 70 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips A) B) C) D) F) E)

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80 Figure D-3 Graphs of results of third core-d rilled anchor group installed with anchor spacing of 5.0 inches A) Load on first anc hor; B) Load on second anchor; C) Load on third anchor; D) Load on fourth anchor; E) Comparison of all anchor loads in test; F) Load on entire anchor group (a)(b) (c)(d) G 5-3 LW 1Instrument Malfunction0 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips G 5-3 LW 2 16.651670 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips G 5-3 LW 3 13.655230 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips G 5-3 LW 4 14.961430 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips (e)(f) G 5-3 LW 1-4 0 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips G 5-3 OLC 61.995050 10 20 30 40 50 60 70 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips A) B) C) D) F) E)

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81 Figure D-4 Graphs of results of first core-d rilled anchor group installed with anchor spacing of 9.0 inches A) Load on first anc hor; B) Load on second anchor; C) Load on third anchor; D) Load on fourth anchor; E) Comparison of all anchor loads in test; F) Load on entire anchor group (a)(b) (c)(d) G 9-1 LW 1Instrument Malfunction0 5 10 15 20 25 30 35 40 45 -0.10-0.050.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips G 9-1 LW 2 27.498680 5 10 15 20 25 30 35 40 45 -0.10-0.050.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips G 9-1 LW 3 28.599580 5 10 15 20 25 30 35 40 45 -0.10-0.050.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips G 9-1 LW 4 25.260890 5 10 15 20 25 30 35 40 45 -0.10-0.050.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips (e)(f) G 9-1 LW 1-4 0 5 10 15 20 25 30 35 40 45 -0.10-0.050.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips G 9-1 OLC 104.594550 10 20 30 40 50 60 70 80 90 100 110 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips A) B) C) D) F) E)

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82 Figure D-5 Graphs of results of second core-d rilled anchor group in stalled with anchor spacing of 9.0 inches A) Load on first anc hor; B) Load on second anchor; C) Load on third anchor; D) Load on fourth anchor; E) Comparison of all anchor loads in test; F) Load on entire anchor group (a)(b) (c)(d) G 9-2 LW 1Instrument Malfunction0 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips G 9-2 LW 2 22.193610 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips G 9-2 LW 3 24.251500 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips G 9-2 LW 4 32.704220 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips (e)(f) G 9-2 LW 1-4 0 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips G 9-2 OLC 105.503090 10 20 30 40 50 60 70 80 90 100 110 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips A) B) C) D) F) E)

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83 Figure D-6 Graphs of results of third core-d rilled anchor group installed with anchor spacing of 9.0 inches A) Load on first anc hor; B) Load on second anchor; C) Load on third anchor; D) Load on fourth anchor; E) Comparison of all anchor loads in test; F) Load on entire anchor group (a)(b) (c)(d) G 9-3 LW 1Instrument Malfunction0 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips G 9-3 LW 2 21.061490 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips G 9-3 LW 3 23.348210 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips G 9-3 LW 4 25.522930 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips (e)(f) G 9-3 LW 1-4 0 5 10 15 20 25 30 35 40 45 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips G 9-3 OLC 100.317560 10 20 30 40 50 60 70 80 90 100 110 0.000.050.100.150.200.25 Axial Displacement, inTensile Load, kips A) B) C) D) F) E)

PAGE 95

84 APPENDIX E REPRESENTATIVE PHOTOGRAPHS OF ANCHOR SPECIMENS FROM TESTING Figure E-1 Typical grout/concrete bond failure of single core-d rilled anchor with grout plug Figure E-2 Typical grout/concre te bond failure of single anc hor with secondary shallow concrete cone

PAGE 96

85 Figure E-3 Grout/concrete bond failure of si ngle core-drilled anchor with secondary shallow cone removed and grout plug exposed Figure E-4 Typical grout/concre te bond failure of single ha mmer-drilled anchor with grout plug

PAGE 97

86 Figure E-5 Typical grout/concre te bond failure of single ha mmer-drilled anchor with secondary shallow concrete cone and grout plug Figure E-6 Typical grout/concrete bond failure of single core-d rilled anchor installed 4.5 inches from one edge with grout plug a nd diagonal cracking of surrounding concrete

PAGE 98

87 Figure E-7 Typical grout/concrete bond failure of single core-d rilled anchor installed 6.0 inches from one edge with grout plug Figure E-8 Typical grout/concrete bond failure of single core-d rilled anchor installed 7.5 inches from one edge with grout plug

PAGE 99

88 Figure E-9 Typical surface view of cone failu re of quadruple fastener anchor group with anchor spacing of 5 inches Figure E-10 Typical dissection vi ew of cone failure of quadr uple fastener anchor group with anchor spacing of 5 inches

PAGE 100

89 Figure E-11 Typical grout/concrete failure of quadruple fastener anchor group with anchor spacing of 9 inches

PAGE 101

90 APPENDIX F COMPILATION OF PRODUCT APPROVAL TEST RESULTS 0 5 10 15 20 25 30 35 40 051015202530 CA Curing Time (days)Tensile Load (kips) Individual Average Figure F-1 Strength versus curing time for product CA 0 5 10 15 20 25 30 35 40 051015202530 CG Curing Time (days)Tensile Load (kips) Individual Avera g e Figure F-2 Strength versus curing time for product CG

PAGE 102

91 0 5 10 15 20 25 30 35 40 051015202530 PB Curing Time (days)Tensile Load (kips) Individual Avera g e Figure F-3 Strength versus curing time for product PB 33.1 18.5 29.2 3 3.6 13.70 5 10 15 20 25 30 35 CACGPB ProductAverage Failure Load (kip) Threaded Rod Smooth Rod Figure F-4 Comparison of average failure load s for installation with threaded rods and smooth rods

PAGE 103

92 3.02 2.16 2.23 2.2 3.31 1.06 3.06 2.310 0.5 1 1.5 2 2.5 3 3.5 CBCCCDCF ProductAverage Bond Stress ( ) (ksi) Reinforcing Bar Threaded Rod Figure F-5 Comparison of averag e bond stresses for installati on with threaded rods and reinforcing bars 39.12 37.77 23.6 34.85 33.27 30.57 21.81 38.220 5 10 15 20 25 30 35 40 45 CACBCCPA ProductAverage Failure Load (kip) Hex Nut Heavy Hex Nut Figure F-6 Comparison of average failure load s for installation of headed anchors with regular hex nuts and heavy hex nuts

PAGE 104

93 29.34 35.1 30.3 28.97 0 5 10 15 20 25 30 35 40 Test Series 1Test Series 2 Product CAAverage Failure Load (kip) Core-drilled Hole Hammer-drilled Hole Figure F-7 Comparison of average failure lo ads for installation in core-drilled and hammer-drilled holes 0.84 0.96 0.97 0.93 0.8 0.71 0 0.2 0.4 0.6 0.8 1 1.2 PAPBPC ProductAverage Bond Stress ( 0) (ksi) Dry Hole Damp Hole Figure F-8 Comparison of aver age bond stresses for installation in damp and dry holes

PAGE 105

94 21.02 24.1 19.69 22.680 5 10 15 20 25 30 PAPB ProductAverage Failure Load (kips) 72 Degrees Fahrenheit 110 Degrees Fahrenheit Figure F-9 Comparison of average failure lo ads for tests performed at ambient and elevated temperatures

PAGE 106

95 REFERENCE LIST ACI Committee 318 (2002), Building Code Requi rements for Structur al Concrete (ACI 318-02) and Commentary (318R-02), Amer ican Concrete Institute, Farmington Hills, Michigan. American Society for Testing and Materials (ASTM) (2001a), Standa rd Test Method for Compressive Strength of Cyli ndrical Concrete Specimens, Annual Book of ASTM Standards C 39-01. West Conshohocke n, Pennsylvania, pp. 18-22. American Society for Testing and Materials (ASTM) (2001b), Standard Test Method for Compressive Strength of Hydraulic Cement Mortars (Using 2-i n. or [50-mm] Cube Specimens), Annual Book of ASTM Standards C 109-99. West Conshohocken, Pennsylvania, pp. 83-88. American Society for Testing and Materials (ASTM) (2001c), Standa rd Test Method for Flow of Grout for Preplaced-Aggreg ate Concrete (Flow Cone Method), Annual Book of ASTM Standards C 939-97. West Conshohocken, Pennsylvania, pp. 494496. American Society for Testing and Materials (ASTM) (2001d), Standard Test Method for Strength of Anchors in Conc rete & Masonry Elements, Annual Book of ASTM Standards E 488-96. West Conshohocke n, Pennsylvania, pp. 66-73. American Society for Testing and Materials (ASTM) (2001e), Standa rd Test Method for Testing Bond Performance of Bonded Anchors, Annual Book of ASTM Standards E 1512-01. West Conshohocke n, Pennsylvania, pp. 660-664. Cook, R. A., and Konz, R. C. (2001), Factor s Influencing Bond St rength of Adhesive Anchors, ACI Structural Journal Vol. 98, No. 1, pp. 76-86. Cook, R. A., Kunz, J., Fuchs, W., and Konz, R. C. (1998), Behavior and Design of Single Adhesive Anchors under Tensile Load in Uncracked Concrete, ACI Structural Journal Vol. 95, No. 1, pp. 9-26. Florida Department of Transportation (FDOT ) (2000), Florida Method of Test for Anchor System Tests for Adhesive-Bonded Anchor s and Dowels, Florida Department of Transportation, FM 5-568. Tallahassee, Florida. Florida Department of Transportation (F DOT) (2002a), Adhesive Bonding Material Systems for Structural Applications, Florid a Department of Transportation, Section 937. Tallahassee, Florida.

PAGE 107

96 Florida Department of Transportation (FDOT ) (2002b), Structures Design Guidelines for Load and Resistance Factor Design, Flor ida Department of Transportation, Tallahassee, Florida. Fuchs, W., Eligehausen, R., and Breen, J. E. (1995), Concrete Capacity Design (CCD) Approach for Fastening to Concrete, ACI Structural Journal Vol. 92, No. 1, pp. 7394. International Congress of Building Offici als Evaluation Services (ICBO ES) (2001), Acceptance Criteria for Adhesive Anchor s in Concrete and Masonry Elements, International Congress of Building Offici als Evaluation Services, AC58. Whittier, California, pp. 1-14. James, R. W., De la Guardia, C., and Mc Creary, Jr., C. R. (1987), Strength of EpoxyGrouted Anchor Bolts in Concrete, Journal of Structural Engineering American Society of Civil Engineers, Vol. 113, No. 12, pp. 2365-2381. Kornreich, B. (2001), Grouted and Adhesive Anchor Tests: Chemrex Products 1090, Thoroc 10-60, 648 CP+, 928, Masters Report, University of Florida, Gainesville, Florida. Lehr, B., and Eligehausen, R. (2001), Design of Anchorages with Bonded Anchors under Tension Load, Connections between Steel and Concrete Vol. 1, University of Stuttgart, Germany, pp. 411-421. McVay, M., Cook, R. A., and Krishnamur thy, K. (1996), Pullout Simulation of Postinstalled Chemically Bonded Anchors, Journal of Structural Engineering American Society of Civil Engineers, Vol. 122, No. 9, pp. 1016-1024. National Instruments Corporation (NI) (1999 ), LabVIEW Development System (Version 5.1), [Computer program]. Available fr om National Instruments Corporation, 11500 North Mopac Expressway, Austin Texas 78759-3504. Zamora, N. A. (1998), Behavi or and Design of Headed a nd Unheaded Grouted Anchors Loaded in Tension, Masters Report, Universi ty of Florida, Gainesville, Florida. Zamora, N. A., Cook, R. A., Konz, R. C., a nd Consolazio, G. R. (2003), Behavior and Design of Headed and Unheaded Grouted Anchors Loaded in Tension, ACI Structural Journal Vol. 100, No. 2, pp. 222-230.

PAGE 108

97 BIOGRAPHICAL SKETCH The author was born on November 4, 1979, in Florida. She began attending the Massachusetts Institute of Technology in September 1998 after graduating from high school in Davie, Florida. Af ter receiving the degree of B achelor of Science in Civil Engineering from the Massachusetts Instit ute of Technology in June 2001, she began graduate school in the College of Engineering at the University of Florida. She plans to receive her Master of Engin eering degree in August 2003, with a concentration in civil engineering structures after which time she will pursue a career in structural design. The author is a member of American Society of Civil Engineers, Chi Epsilon, and Tau Beta Pi.


Permanent Link: http://ufdc.ufl.edu/UFE0000854/00001

Material Information

Title: Behavior and Design of Grouted Anchors Loaded in Tension Including Edge and Group Effects and Qualification of Engineered Grout Products
Physical Description: Mixed Material
Copyright Date: 2008

Record Information

Source Institution: University of Florida
Holding Location: University of Florida
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Permanent Link: http://ufdc.ufl.edu/UFE0000854/00001

Material Information

Title: Behavior and Design of Grouted Anchors Loaded in Tension Including Edge and Group Effects and Qualification of Engineered Grout Products
Physical Description: Mixed Material
Copyright Date: 2008

Record Information

Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
System ID: UFE0000854:00001


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BEHAVIOR AND DESIGN OF GROUTED ANCHORS LOADED IN TENSION
INCLUDING EDGE AND GROUP EFFECTS AND QUALIFICATION OF
ENGINEERED GROUT PRODUCTS













By

JENNIFER LYNN BURTZ


A THESIS PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS OF THE DEGREE OF
MASTER OF ENGINEERING


UNIVERSITY OF FLORIDA


2003















ACKNOWLEDGMENTS

There are many individuals whose aid and guidance made this thesis and the

accompanying research a success. The author extends the utmost thanks to Dr. Ronald

A. Cook. His extensive knowledge and support proved invaluable. The discussions held

with Dr. H. R. Hamilton, III were extremely useful in the development of aspects of the

testing program. In addition, the author wishes to thank Dr. John M. Lybas for his help

in the completion of this thesis.

The author also wishes to thank Johnny Fung, Brian Simoneau, Chuck Broward,

Vanessa Grillo, Kim Lammert, and Brian Kornreich for their assistance, knowledge, and

time.

Appreciation is also owed to Marcus Ansley from the Florida Department of

Transportation for his knowledge and financial support and to Walter Hanford from

Chemrex for his generous donation of materials.

Finally, the author is indebted to her close friends and family. The value of their

support cannot be measured.















TABLE OF CONTENTS

page

A C K N O W L E D G M E N T S .................................................................................................. ii

TA BLE O F CON TEN TS................................................................... ......................... iii

LIST OF TABLES .................... ............ ........ .......... .........vi

L IST O F FIG U R E S .... ....... ...................... ........................ .... ...... .. ............. vii

ABSTRACT ........ .............. ............. ..... .......... .......... xi

CHAPTER

1. IN TR OD U CTION ....................... ........................ ........... ..... .. 1

2. BA CK GROUN D ....................... .............................. .................. 2

2.1 Types of A nchor System s ......................................................... .............. 2
2.2 Bonded Anchors................................. ................ 3
2 .2 .1 A dh esiv e A n ch ors ......................................................... .. .. ......... ......... 4
2.2.2 Grouted Anchors ............................................ ... ..... .............. 6
2.3 Previous and Current Studies with Grouted Anchors .......................................... 8

3. BEHAVIORAL M ODELS ........................................................... ............... 11

3.1 G general ..................................... .............................. ........ ........... 11
3.2 Concrete Capacity Design (CCD) Method ..................................................... 11
3.3 U uniform B ond Stress M odel ............................................. .......................... 12

4. DEVELOPMENT OF TEST PROGRAM ....................................... ............... 17

4 .1 G e n e ra l ................... ............................................................... 1 7
4.2 Single G routed A nchor Test Program ............................................... .. ................. 18
4.3 G group G routed A nchor Test Program ............................................... .. ................. 20

5. IMPLEMENTATION OF TEST PROGRAM ................................... ...............21

5 .1 G en e ral ................................................................................... 2 1









5 .2 C o n create ..................................................... 2 1
5 .3 Sp ecim en P rep aration ........................................................................................... 22
5 .4 In stallation P ro cedu re ........................................................................................... 2 3
5 .5 A p p a ratu s ............................................. .. ............................................... 2 4
5 .6 L loading P rocedu re ................................................. ................................ .. 2 6
5.7 Data Reduction............................... .. .. .. .... .. ............ 29
5.7.1 Displacement Calculations for Single Anchor Tests ................................. 29
5.7.2 Displacement Calculations for Group Anchor Tests ................................. 29

6. T E ST R E SU L T S ....... .. .............. ...................... ....... .... ........ ............. 3 1

6.1 G general ....................... .... ... ................. ................ .......... 31
6.2 Single G routed A nchor Test R esults............................................... .... .. .............. 31
6.3 G group G routed A nchor Test R esults............................................... .... .. .............. 34

7. TESTED FACTORS INFLUENCING GROUT BOND STRENGTH.....................36

7 .1 G en e ral .......................................................................... ............... 3 6
7.2 Strength versus Curing Tim e ..................................... ....................... ................ 36
7.3 Threaded Rod versus Deformed Reinforcing Bar .......................................... 37
7.4 Threaded Rod versus Smooth Rod .................... ........................ ........... 37
7.5 Regular Hex Nut versus Heavy Hex Nut.......................................................... 38
7.6 H ole D rilling Technique ............................................... ............................ 39
7.7 D am p H ole Installation ....................................................................... 39
7.8 E elevated Tem perature ........................................................................ 40
7.9 Sum m ary ...................................... ................................. ........ 40

8. DISCUSSION ON DESIGN METHOD FOR GROUTED ANCHORS ..................42

8.1 Current M odels ..................... ............ .................... 42
8.2 Predicted Model for Grouted Anchor Behavior............................................... 42
8.3 Proposed Critical Edge Distance and Critical Anchor Spacing Revision........... 43
8.4 Proposed Model for Single Grouted Anchors........................................... 45
8.5 Proposed Design Model for Grouted Anchor Groups ....................................... 47

9. DISCUSSION ON PROPOSED PRODUCT APPROVAL TESTS .........................48

9 .1 G en e ral ............................ ..................................................... 4 8
9.2 G rout/Concrete B ond Stress (To).......................................................... ... 49
9.3 Test Series to Establish Steel/Grout Bond Stress (c) .......................................... 49
9.4 Strength versus Curing Tim e ............................................................... ........... 50
9.5 Threaded Rod versus Deformed Reinforcing Bar .......................................... 50
9.6 H ole D rilling Technique ........................ ............................... ........................... 51
9.7 M oisture C condition of H ole ......................................................................... ... 51
9.8 Elevated Tem perature .................................................... .................................. 53
9.9 Horizontal and Overhead Hole Orientation (Optional) ...................................... 53









9.10 Long-term Load (Optional)..................................................................... 55
9.11 A additional Factors................... ....... ...................... .................... .. .............. .. 56

10. SUMMARY, CONCLUSIONS, AND RECOMMENDATIONS.............................. 57

1 0 .1 S u m m a ry ............................................................................................................. 5 7
10.2 C conclusions ........................................... 57
10.3 R ecom m endations ................ ........ .. ... .................. ............. 59

APPENDIX

A N OTATION ......... .... ........................................................................61

B TENSILE LOAD VS. DISPLACEMENT GRAPHS FOR BASELINE
AND HOLE DRILLING TECHNIQUE TEST SERIES................... ........ ........64

C TENSILE LOAD VS. DISPLACEMENT GRAPHS FOR EDGE
DISTAN CE TEST SERIES ............................................................ ............... 71

D TENSILE LOAD VS. DISPLACEMENT GRAPHS FOR GROUP
TEST SER IE S ..................... .................... ...........................76

E REPRESENTATIVE PHOTOGRAPHS OF ANCHOR SPECIMENS
FR OM TESTIN G .......................................................... .............. ... 84

F COMPILATION OF PRODUCT APPROVAL TEST RESULTS .............................90

R E F E R E N C E L IS T ................................................................................ ....................9 5

B IO G R A PH IC A L SK E TCH ..................................................................... ..................97















LIST OF TABLES


Table pae

5-1 Summary of testing program for grout product CA ......................... ...............23

5-2 G rout installation sum m ary .............................................................. .....................24

6-1 Summary of single anchor test results exhibiting bond failure .................................32

6-2 Summary of baseline single anchor test results ........................................................34

6-3 Summary of multiple anchor test results ............................ ................................ 35

7-1 Summary of tested factors influencing grout bond strength.................. ............41

B-1 Individual baseline and hole drilling technique anchor test results............................65

C-l Individual edge distance anchor test results..................................... ............... 72

D Individual group anchor test results....................................... ......................... 77















LIST OF FIGURES


Figure pae

2-1 T ypes of anchor system s................................................................ ....................... 2

2-2 Examples of typical unheaded and headed grouted anchors ...................................

2-3 Typical bond failures at the steel/grout and grout/concrete interfaces for
unheaded grouted anchors.................................................. ............................... 7

2-4 Typical bond failure at the grout/concrete interface and concrete cone breakout
failure of headed grouted anchors.............................. ........................................... 8

3-1 Calculation of ANo for the CCD method ............ ................................ ............... 12

3-2 Projected areas for single anchors and anchor groups for the CCD method .............. 13

3-3 Calculation of ANo for the uniform bond stress model using the anchor diameter ......14

3-4 Projected areas for single anchors and anchor groups for the uniform bond
stress m odel using the anchor diam eter ................................. .......... ................... 15

3-5 Calculation of ANo for the uniform bond stress model using the hole diameter.......... 15

3-6 Projected areas for single anchors and anchor groups for the uniform bond
stress m odel using the hole diam eter ................................. ...................................... 15

5-1 Single anchor test apparatus ............................................... ............................. 26

5-2 G roup anchor test apparatus ............................................... ............................. 27

5-3 Minimum reaction positions of test apparatus for headed anchors .............................27

5-4 Diagram of displacement calculation for individual anchor in group test ..................30

8-1 Critical edge distance of 8do compared to experimental results.............................44

8-2 Critical anchor spacing of 16do compared to experimental results ...........................44

8-3 Critical edge distance of 5do compared to experimental results..............................45









8-4 Critical anchor spacing of 10do compared to experimental results ...........................46

B-l Graphs of test results of first installation of core-drilled anchors.............................66

B-2 Graphs of test results of second installation of core-drilled anchors..........................67

B-3 Graphs of test results of third installation of core-drilled anchors..............................68

B-4 Graphs of test results of first installation of hammer-drilled anchors ........................69

B-5 Graphs of test results of second installation of hammer-drilled anchors ..................70

C-1 Graphs of test results of core-drilled anchors installed 4.5 inches away
fro m o n e ed g e ....................................................... ................ 7 3

C-2 Graphs of test results of core-drilled anchors installed 6.0 inches away
fro m o n e ed g e ....................................................... ................ 7 4

C-3 Graphs of test results of core-drilled anchors installed 7.5 inches away
fro m o n e ed g e ....................................................... ................ 7 5

D-1 Graphs of results of first core-drilled anchor group installed with anchor
spacing of 5.0 inches ................. ........................ ................... ......... 78

D-2 Graphs of results of second core-drilled anchor group installed with anchor
spacing of 5.0 inches ................. ........................ ................... ......... 79

D-3 Graphs of results of third core-drilled anchor group installed with anchor
spacing of 5.0 inches ................. ........................ ................... ......... 80

D-4 Graphs of results of first core-drilled anchor group installed with anchor
spacing of 9.0 inches ............................................. .... ........... .... ........ 81

D-5 Graphs of results of second core-drilled anchor group installed with anchor
spacing of 9.0 inches ........................................................... ............. 82

D-6 Graphs of results of third core-drilled anchor group installed with anchor
spacing of 9.0 inches ........................................................... ............. 83

E-l Typical grout/concrete bond failure of single core-drilled anchor with
grout plug ................................................................. ...... ........... 84

E-2 Typical grout/concrete bond failure of single anchor with secondary shallow
concrete cone ........................................... ........................... 84









E-3 Grout/concrete bond failure of single core-drilled anchor with secondary
shallow cone removed and grout plug exposed .................................. ............... 85

E-4 Typical grout/concrete bond failure of single hammer-drilled anchor with
grout plug ................................................................. ...... ........... 85

E-5 Typical grout/concrete bond failure of single hammer-drilled anchor with
secondary shallow concrete cone and grout plug ....................................... .......... 86

E-6 Typical grout/concrete bond failure of single core-drilled anchor installed
4.5 inches from one edge with grout plug and diagonal cracking of surrounding
c o n c rete ...................................... ................................................... 8 6

E-7 Typical grout/concrete bond failure of single core-drilled anchor installed
6.0 inches from one edge with grout plug........................................ ............... 87

E-8 Typical grout/concrete bond failure of single core-drilled anchor installed
7.5 inches from one edge with grout plug........................................ ............... 87

E-9 Typical surface view of cone failure of quadruple fastener anchor group
w ith anchor spacing of 5 inches.......................................... ............................ 88

E-10 Typical dissection view of cone failure of quadruple fastener anchor group
w ith anchor spacing of 5 inches........................................................................ .. ...88

E-11 Typical grout/concrete failure of quadruple fastener anchor group with
anchor spacing of 9 inches............................................... .............................. 89

F-l Strength versus curing time for product CA .................................... ............... 90

F-2 Strength versus curing time for product CG .................................... ............... 90

F-3 Strength versus curing tim e for product PB ..................................... .................91

F-4 Comparison of average failure loads for installation with threaded rods
and sm ooth rods ....................................................................... 9 1

F-5 Comparison of average bond stresses for installation with threaded rods
and reinforcing bars ...................... ...................... ................... .. ...... 92

F-6 Comparison of average failure loads for installation of headed anchors
with regular hex nuts and heavy hex nuts .........................................................92

F-7 Comparison of average failure loads for installation in core-drilled and
ham m er-drilled holes ............................................................. 93









F-8 Comparison of average bond stresses for installation in damp and dry holes ............93

F-9 Comparison of average failure loads for tests performed at ambient and
elev ated tem peratures....... ................................................................... .............. 94















Abstract of Thesis Presented to the Graduate School
Of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Master of Engineering

BEHAVIOR AND DESIGN OF GROUTED ANCHORS LOADED IN TENSION
INCLUDING EDGE AND GROUP EFFECTS AND QUALIFICATION OF
ENGINEERED GROUT PRODUCTS

By

Jennifer Lynn Burtz

August 2003

Chair: Ronald A. Cook
Major Department: Civil and Coastal Engineering

Based on experimental test results, a set of design equations were developed for

computing the tensile pullout resistance of headed and unheaded single and group

grouted anchors. Edge distance and group spacing effects are considered, and values for

the critical edge distance and critical anchor spacing are proposed. The results of this

testing program, along with those from previous experimental programs, were analyzed

to ascertain grout susceptibility to various installation and in-service factors. Stemming

from these results, a series of product approval tests was proposed to determine if an

engineered grout product is suitable for a desired application.















CHAPTER 1
INTRODUCTION

A typical grouted anchor consists of a steel rod and the grout product installed

into a hole drilled in hardened concrete. Grout products can be either cementitious or

polymer based and installed into the hole with a headed or unheaded anchor. This paper

explores the behavior of both single and groups of grouted anchors loaded in tension in

uncracked concrete. The parameters considered are hole drilling technique, anchor

diameter, edge effects, and group effects. These results, along with the results from

existing test databases, form the basis for a proposed design model for grouted anchors

and product approval tests for engineered grout products.

The American Concrete Institute (ACI) 318-02 (ACI 2002) includes a new

Appendix D addressing anchorage to concrete. Design procedures for cast-in-place

anchors and post-installed mechanical anchors are included in Appendix D. As a result

of extensive testing, the ACI 318 committee is currently working on including adhesive

anchors in Appendix D. Grouted anchors are also being considered for inclusion.















CHAPTER 2
BACKGROUND

2.1 Types of Anchor Systems

Anchor fastenings to concrete can be divided into two main categories: cast-in-

place and post-installed anchors. Figure 2-1 presents a diagram summarizing the types of

anchors available and the products used for installation.


Figure 2-1 Types of anchor systems

Cast-in-place anchors are installed by first connecting them to the formwork prior

to pouring concrete. A cast-in-place anchor is typically composed of a headed steel bolt

or stud. The main load transfer mechanism is through bearing on the head. Extensive

testing has been performed on cast-in-place anchors, and a design model has been









developed to accurately predict their behavior. Systems comprised of cast-in-place

anchors behave predictably but are fixed in their location after the concrete is cast.

Post-installed anchors offer more flexibility, and their use is now common.

Systems of post-installed anchors include: mechanical (expansion and undercut) and

bonded (adhesive and grouted) anchors. Expansion anchors are installed by expanding

the lower portion of the anchor through either torque-controlled or displacement-

controlled techniques, and load is transferred through friction between the hole and the

expanded portion of the anchor. Undercut anchors are installed in a similar manner to

expansion anchors, but they possess a slightly oversized hole at the base of the anchor

embedment. Load is transferred through bearing of the base of the undercut anchor on

the hole. Both adhesive and grouted anchors fall under the heading of bonded anchors.

This paper is primarily concerned with the comparison of grouted anchors to cast-in-

place and adhesive anchors.

2.2 Bonded Anchors

Post-installed bonded anchors can be categorized as either adhesive or grouted.

An adhesive anchor can be either an unheaded threaded rod or a deformed reinforcing bar

and is inserted into hardened concrete in a predrilled hole that is typically 10 to 25

percent larger than the diameter of the anchor. These anchors are bonded into the hole

using a two-part structural adhesive consisting of a resin and a curing agent to bind the

concrete and steel together.

Contrastingly, a grouted anchor can be an unheaded threaded rod, a deformed

reinforcing bar, a headed bolt, a headed stud, a smooth rod with a nut on the embedded

end, or a threaded rod with a nut on the embedded end. Grouted anchors are installed

into hardened concrete in predrilled holes that are typically 50 to 200 percent larger than









the diameter of the anchor. For the purposes of this paper, the break point between an

adhesive anchor and a grouted anchor is when the hole diameter is equal to one and a half

times the anchor diameter; all anchors installed in holes greater than or equal one and a

half times the anchor diameter shall be considered as grouted anchors.

Engineered grouts can be cementitious or polymer based. Cementitious grouts are

composed of primarily fine aggregates, portland cement, and water; polymer grouts are

similar in nature to the structural adhesive used to bind adhesive anchors to concrete but

also contain a fine aggregate component.

2.2.1 Adhesive Anchors

The curing time of adhesive products is rapid, which makes them ideal for

situations requiring a quick set. Different products can be used to install adhesive

anchors. These products can be polymers epoxiess, polyesters, or vinylesters) or hybrid

systems. Cook et al. (1998) explain that when the resin and curing agent are mixed, the

products undergo an exothermic reaction resulting in the formation of a polymer matrix

that binds the anchor and the concrete together. Adhesive anchors are typically installed

in clean dry holes to attain maximum bond strength. Applied load is transferred from the

adhesive anchor to the concrete by one of two mechanisms: mechanical interlock or

chemical binding to the concrete.

Cook et al. (1998) proposed a model to design adhesive anchors and to predict

anchor strength. This model was developed by comparing the test results from an

international test database of single adhesive anchors to several different design models.

The uniform bond stress model was proposed and provided the best fit to the database.









McVay et al. (1996) also showed the uniform bond stress model to be rational through

comparison of predictions from nonlinear computer analysis to experimental results.

Product approval standards and guidelines for adhesives currently exist in several

published documents. The International Congress of Building Officials Evaluation

Service (ICBO ES) AC58 (ICBO ES 2001) lists and describes various tests for evaluating

adhesive performance under different anchor configurations and installation conditions.

The mandatory tests include single anchor tests in tension and in shear, critical edge

distance tests for single anchors in tension, tests for critical anchor spacing in anchor

groups, and tests for sensitivity to in-service temperature conditions. The Florida Method

of Test FM 5-568 (FDOT 2000) describes the tests required by the Florida Department of

Transportation (FDOT) for determining the bond strength and sensitivity to installation

and service conditions of adhesive bonded anchors and dowels. This document

references both the American Society for Testing and Materials (ASTM) E 488-96

(ASTM 2001d) and ASTM E 1512-01 (ASTM 2001e) in respect to how tests on anchor

systems should be performed. The FM 5-568 recommends that tension tests, damp hole

installation tests, elevated temperature tests, horizontal orientation tests, short-term cure

tests, and long-term loading tests be performed on anchor systems. Cook and Konz

(2001) experimentally investigated the sensitivity of 20 adhesive products to various

installation and service conditions through 765 tests. Installation factors examined

included variations in the condition of the drilled hole, concrete strength, and concrete

aggregate. Service conditions considered included short-term cure and loading at an

elevated temperature.









2.2.2 Grouted Anchors

Grouted anchors can be bonded to concrete with either polymer or cementitious

products. Anchors bonded with a polymer grout are intended to be installed into dry

holes and under similar conditions as adhesive anchors. Polymer grouts are very similar

to adhesive products in composition. Both polymer adhesive products and polymer

grouts contain a resin component and a curing agent hardenerr), and polymer grouts are

additionally comprised of a third component, a fine aggregate that serves as a filler.

Polymer grouts usually have a rapid cure time, and anchors can be loaded hours after

installation.

The dry components of cementitious grout products are usually prepackaged.

Water is added at the time of installation, according to the manufacturer's guidelines, to

achieve the desired viscosity. Anchors bonded with a cementitious grout are intended to

be installed in clean, damp holes in order to prevent excess water loss into the concrete

from the grout, which would reduce the bond strength of the grout. To ensure that this

does not occur, the holes are usually saturated by filling them with water for a minimum

of 24 hours prior to installation unless otherwise stated in the manufacturer's directions.

Grouted anchors can be installed with or without a head at the embedded end, as

shown in Figure 2-2. The presence of a head, or the lack thereof, affects the load transfer

mechanism from the anchor to the grout. However, load is transferred from the grout to

the concrete primarily through bond and mechanical interlock regardless of the presence

or absence of a head.

Unheaded anchors installed by using a threaded rod or a deformed reinforcing bar

transfer load to the grout through bond and mechanical interlock. These anchors are









expected to experience a bond failure either at the steel/grout interface or the

grout/concrete interface with a secondary shallow concrete cone. Previous testing

performed at the University of Florida by Kornreich (2001) and Zamora (1998) confirms

that these failure modes occur. Figure 2-3 shows the typical failure modes for unheaded

grouted anchors.


do> 1.5d

0-i


Unheaded grouted anchor Headed grouted anchor

Figure 2-2 Examples of typical unheaded and headed grouted anchors


Bond failure at
steel/grout interface


Bond failure at
grout/concrete interface


Figure 2-3 Typical bond failures at the steel/grout and grout/concrete interfaces for
unheaded grouted anchors

Headed anchors installed with a headed bolt or a smooth rod with a nut at the

embedded end of the anchor transfer load to the grout through bearing on the head.


i









These anchors are expected to fail either in a bond failure at the grout/concrete interface

with a secondary shallow cone or in a full concrete cone breakout depending on the bond

strength of the grout. Failure at the steel/grout interface is precluded due to the presence

of the head. Similar to unheaded grouted anchors, previous testing performed at the

University of Florida by Kornreich (2001) and Zamora (1998) confirms these failure

modes occur. Figure 2-4 shows the typical failure modes for headed grouted anchors.












Bond failure at Concrete breakout failure
grout/concrete interface

Figure 2-4 Typical bond failure at the grout/concrete interface and concrete cone
breakout failure of headed grouted anchors

2.3 Previous and Current Studies with Grouted Anchors

Experimental and analytical studies focusing on the strength and behavior of

grouted anchors under tensile load have been presented in published literature. In the

earlier stages of grouted anchor research, the theoretical behavior of polymer grouts was

examined. James et al. (1987) presented an analysis of post-installed epoxy (polymer)

grouted anchors in reinforced concrete based on linear and nonlinear finite element

models and comparisons to previously reported experimental data. Parameters

considered in this study included various ratios of embedment depth to bolt diameter,

different grout properties, and two concrete failure theories: the maximum tensile stress

criteria and the Mohr-Coulomb criteria. According to James et al. (1987), when bond









failure occurs at the grout/concrete interface, testing has shown that the load capacity was

directly related to the size of the drilled hole. As the hole size increased, the load

capacity of the epoxy was increased due to the increase in bond area and displacement of

the head of the bolt also increased. If higher strength grouts are utilized, the shear

strength of the concrete will control, and failure at the grout/concrete interface is

precluded. Additionally, the location of the reaction ring was crucial because, if it was

too close to the anchor, it could result in falsely inflated anchor strength.

Other studies were experimental in nature and examined the behavior of polymer

and cementitious grouts while varying physical parameters. One such experimental study

was reported by Zamora (1998) and contained 290 tension tests on post-installed

unheaded and headed grouted anchors. The bond strength of unheaded and headed

grouted anchors was tested for influence of anchor diameter, hole diameter, embedment

depth, grout product cementitiouss or polymer), installation conditions, and concrete

strength. A product approval test program for grout products was also investigated, and

the following tests were performed: damp hole installation, elevated temperature,

threaded rod versus deformed reinforcing bar, regular hex nut versus heavy hex nut, and a

test series to establish bond stress at the grout concrete interface. Portions from Zamora

(1998) pertaining to behavior and design of grouted anchors installed in uncracked

concrete away from a free edge and under tensile load are presented in Zamora et al.

(2003). Test results showed unheaded grouted anchors experienced a bond failure and, in

general, behaved similar to adhesive anchors, and headed grouted anchors experienced

either a bond failure at the grout/concrete interface or a concrete cone breakout. This

study recommended that the strength of unheaded grouted anchors be predicted using the









uniform bond stress model; the strength of headed grouted anchors was recommended to

be taken as the smaller strength of a bond failure at the grout/concrete interface or a

concrete cone breakout. Differences in bond strengths were found to exist between

installation of threaded rods and deformed reinforcing bars when cementitious grouts

were utilized. Cementitious grouts experienced a lower bond strength when installed

using a heavy hex nut as opposed to a regular hex nut; the effect was opposite for the one

polymer grout product tested. Additionally, tests indicated that the bond strength of

polymer grouts was generally reduced with an increase in temperature or damp hole

installation. These results are discussed in detail in Chapter 7.

In a more recent experimental program, Komreich (2001) tested post-installed

headed and unheaded grouted anchors by varying several parameters. Tests included:

grout strength versus curing time, bond of grout to smooth steel, bond of grout to

concrete, and basic bond strength at the steel/grout interface. Based on the results

obtained, recommended design equations were presented including capacity reduction

factors.

In the present paper, the results of post-installed headed grouted anchor tests

examining the effects of hole drilling technique, edge distance effects, and group spacing

effects are presented. The results from previous studies and existing test databases on

headed and unheaded grouted anchors and cementitious and polymer grouts are

considered. All of this information is combined into recommendations for design

specifications for grouted anchors and product approval tests for engineered grout

products.















CHAPTER 3
BEHAVIORAL MODELS

3.1 General

In previous testing programs, grouted anchors were expected to behave in a

similar manner to either cast-in-place headed anchors or post-installed adhesive anchors

depending on whether the anchors were headed or unheaded. Both cast-in-place headed

anchors and post-installed adhesive anchors have been extensively studied, and

behavioral models have been developed that accurately predict anchor strength. The

Concrete Capacity Design (CCD) method and the uniform bond stress model were

therefore used to evaluate the behavior of grouted anchors in this test program, as well as

in previous test programs. The development, applicability, and general equations of these

models are presented in the following sections.

3.2 Concrete Capacity Design (CCD) Method

Fuchs et al.(1995) first proposed the CCD method in 1995. This model was

created to predict the failure loads of cast-in-place headed anchors and post-installed

mechanical anchors loaded in tension or in shear that form a full concrete cone. The

mean tensile capacity for single cast-in-place headed anchors installed in uncracked

concrete is predicted by the following equations:


N0, = 40fch 15 (lbf) ( a)

or











N,c =16.7 che (N) (lb)


Similarly, the CCD method predicts the tensile capacity of cast-in-place headed anchor

groups using the following equations:


A
Nc = A eN,o (lbforN)
N (2)

where ,, = 0.7+0.3 C
1.5hef


Figures 3-1 and 3-2 are adapted from figures found in ACI 318-02 Appendix D (ACI

2002). Figure 3-1 illustrates the calculation of ANo. Figure 3-2 depicts the projected

areas for single anchors and groups of anchors for the CCD method as well as the

calculation of AN.











I [2(.-)*] I[ I-S M


Figure 3-1 Calculation ofANo for the CCD method

3.3 Uniform Bond Stress Model

As mentioned in the previous chapter, Cook et al. (1998) compared several

different models, and the uniform bond stress model using the anchor diameter was found

to be the best fit to the test database. As a result, a uniform bond stress can be assumed









along the entire embedment depth of the adhesive anchor and accurately predict the bond

strength when the embedment length does not exceed 25 times the anchor diameter. For



i, r-'--.-



A.; .1.5hdX2 x 1.5,hr]
if',<1 A (c, +i z, t+. I '"at + I .sl,)
u'lll l''ll iT '14^

Figure 3-2 Projected areas for single anchors and anchor groups for the CCD method

grouted anchors with the hole diameter greater than or equal to one and a half times the

anchor diameter, bond failure can be distinguished at either the steel/grout interface or at

the grout/concrete interface. Zamora et al. (2003) presented two variations of this model

to account for failure at the inner and outer surfaces of the bonding agent as shown in the

following equations for single anchors installed away from a free edge:


NTo = cX dhf (lbforN) (3)



No,o ='c 7 do h (lbforN) (4)


Lehr and Eligehausen (2001) proposed an extension of the uniform bond stress

model for unheaded adhesive anchor groups shown below in Equation (5). This equation

could also be applied to grouted anchor groups that experience a bond failure at the

steel/grout interface. When bond failure occurs at the grout/concrete interface, Equation

(5) may be revised as shown in Equation (6). In this way, the tensile capacity of anchor

groups can be predicted by the uniform bond stress model using the following equations:











A
N, = A eN, (lbforN)
ANO (5)


where Y =0.7+0.3-C
8d





N AN T ,No (lbforN)
(6)

where = 0.7 +0.3
8d,



Figures 3-3 through 3-6 are adapted for the uniform bond stress model from

similar figures for the CCD method found in ACI 318-02 Appendix D (ACI 2002).

Figures 3-3 and 3-5 show the calculation ofANo for bond failure at the steel/grout and

grout/concrete interfaces, respectively. Figures 3-4 and 3-6 depict the projected areas for

single anchors and groups of anchors for the uniform bond stress model as well as the

calculation of AN at the steel/grout and grout/concrete interfaces, respectively.




8d



8d

8d 8d

AN = [2(8)d][2(8)d]
= 256 d


Figure 3-3 Calculation ofANo for the uniform bond stress model using the anchor
diameter




















Ifc,<8d AN =(c + s, + 8d)(c+ s, + 8d)
Ifc and c <8d
ands1 and s2 < 16d


Figure 3-4 Projected areas for single anchors and anchor groups for the uniform bond
stress model using the anchor diameter






8 do



8do


8 do 8 do


ANO =[2(8)do][2(8)dd
= 256 do2


Figure 3-5 Calculation ofANo for the uniform bond stress model using the hole diameter




8 dc1 s, 8 do

8 do
8do S +


AN =(c + 8do)(2 x 8do)
If c, <8do A = (c, +s, + 8do)(c2 +s + 8do)
If c and c2 <8do
ands, and s2 < 16do


Figure 3-6 Projected areas for single anchors and anchor groups for the uniform bond
stress model using the hole diameter


Since adhesive anchors are typically installed in holes with diameters only 10 to


25 percent larger than the anchor diameter, Zamora (1998) conjectured that it is difficult


to differentiate between a failure at the steel/grout interface and the grout/concrete


interface. However, grouted anchors are usually installed in holes with diameters ranging









from 50 to 200 percent larger than the anchor diameter. The larger hole size makes it

easier to determine at which interface a bond failure occurred.

Equation (3) has been shown by Cook et al. (1998) to be a good approximation of

single adhesive anchor tensile strength even though the interface at which bond failure

occurred is not always readily apparent. Similarly, Equation (5) is applicable to groups

of adhesive anchors according to Section 7.12 of the Structures Design Guidelines for

Load and Resistance Factor Design (FDOT 2002b). In general, both Equation (3) and

Equation (4) are applicable to evaluating the strength of single grouted anchors since the

interface at which bond failure occurred is more easily observed. For headed grouted

anchors experiencing bond failure, only Equation (4) should be considered when

determining the tensile strength since failure at the steel/grout interface is precluded by

the presence of the head. The applicability of Equation (6) to headed grouted anchor

groups will be examined in this test program.















CHAPTER 4
DEVELOPMENT OF TEST PROGRAM

4.1 General

The objective of this test program was to perform additional grouted anchor tests

in order to provide a more complete picture of the behavior of engineered grout products.

The results of these tests, along with current test databases, will be used to evaluate the

applicability of existing design models, to recommend a design model to predict strength

of grouted anchors, and to advocate a series of product approval tests to perform in the

assessment of engineered grouts. Previous test programs have not fully addressed the

failure mode of grouted anchors at the grout/concrete interface. In order to develop a

complete design model, this failure mode needs to be further examined.

To investigate the behavior of grouted anchors experiencing this failure mode,

this test program chose certain parameters in an attempt to force a failure at the

grout/concrete interface. Concrete strength was selected to prevent a concrete cone

breakout failure. All anchor specimens were post-installed with a non-shrink

cementitious grout product, CA cementitiouss grout product A) for the purposes of this

paper, as headed anchors to preclude a failure at steel/grout interface. In addition, the

hole diameter was minimized, allowing only a small clearance between the heavy hex nut

of the headed anchor and the side of the hole, to promote a grout/concrete bond failure.

To properly evaluate this failure mode, other anchor parameters were varied. The

experimental program included factors often encountered during design and installation

of anchors including hole drilling technique (diamond-headed core drill or rotary impact









hammer drill), anchor diameter, edge distance effects, and group spacing effects.

Embedment depth was held constant. The test program was separated into two primary

sections: single and group grouted anchor tests. In general, each single anchor series

consisted of at least three repetitions, and each group anchor series consisted of three

repetitions.

4.2 Single Grouted Anchor Test Program

In the single grouted anchor test program, three separate installations of headed

grouted anchors were conducted. Each installation contained a baseline series of anchors

grouted into core-drilled holes. All baseline series consisted of three repetitions except

the first baseline series, which contained five tests. Other installation parameters were

explored in addition to the baseline series of tests to establish which factors affect the

general anchor strength and to quantify this effect where present.

The first installation in the single grouted anchor test program was comprised of

ten anchors, separated into two series of five, and aimed to test the potential effects of

hole drilling techniques. All ten anchors were 0.625 inch (15.9 mm) in diameter, smooth

steel rods with threaded ends, and headed using a heavy hex nut. In addition, the

embedment depth was 5 inches (127.0 mm) measured from the top of the nut to the top of

the concrete, and the edge distance of 12 inches (304.8 mm) was sufficiently large to

eliminate concern of edge distance effects. The baseline series consisted of five of the

aforementioned anchors damp-installed into core-drilled holes 1.5 inches (38.1 mm) in

diameter. The second single anchor series in the first installation varied one factor from

the baseline series; these five anchors were damp-installed into hammer-drilled holes 1.5

inches (38.1 mm) in diameter.









The second installation in this test program consisted of 11 anchors with the

purpose of examining edge effects and to further inquire into effects arising from hole

drilling techniques. All anchors in this installation were 0.75 inch (19.1mm) in diameter,

smooth steel rods with threaded ends, and headed using a heavy hex nut. As in the

previous installation, all anchors were embedded 5 inches (127.0 mm), and all holes were

1.5 inches (38.1 mm) in diameter. The baseline series consisted of three anchors damp-

installed into core-drilled holes. The second series in this installation contained three

anchors damp-installed into hammer-drilled holes. All anchors in both of these series

were installed a minimum of 15 inches (381 mm) from the edge of the concrete block to

eliminate the possibility of edge effects. The final test series on this installation was

comprised of five anchors damp-installed in proximity to a single edge. These anchors

were 7.5 inches (190.5 mm) from one edge and a minimum of 24 inches (609.6 mm)

from all additional edges.

The third installation contained 13 anchors and endeavored to observe edge

distance effects in more detail. All anchors in this installation were 0.75 inch (19.1 mm)

in diameter, smooth steel rods with threaded ends, and headed with a heavy hex nut.

Again, all anchors were embedded 5 inches (127.0 mm); all holes were core-drilled and

1.5 inches (38.1 mm) in diameter. The baseline series consisted of three anchors damp-

installed and placed a minimum of 15 inches (381 mm) from all edges to preclude this

type of effect. The two edge effects series included five anchors damp-installed 6 inches

(152.4 mm) from one edge and five anchors damp-installed 4.5 inches (114.3 mm) from

one edge. All ten anchors were placed a minimum of 24 inches (609.6 mm) from the

remaining edges.









4.3 Group Grouted Anchor Test Program

In the group grouted anchor test program, two separate installations of quadruple

fastener headed grouted anchor groups were carried out. In order to evaluate the group

effect, the single anchor strength No must be established. For this reason, a baseline

series, as discussed in the previous section, was installed in the same concrete on the

same day as the group specimens. This allowed for a direct comparison of group strength

to the strength of a single anchor.

The first quadruple fastener series of three tests was installed in the first

installation. Each anchor group contained four anchors 0.625 inch (15.9 mm) in diameter

with smooth steel shafts, threaded ends, and headed using heavy hex nuts. All anchors

were embedded 5 inches (127.0 mm) deep in holes 1.5 inches (38.1 mm) in diameter and

spaced 5 inches (127.0 mm) from each adjacent anchor to form a square.

The second series of three tests was installed in the third installation. Each anchor

group included four anchors 0.75 inch (19.1 mm) in diameter with smooth steel shafts,

threaded ends, and headed using heavy hex nuts. All anchors were embedded 5 inches

(127.0 mm) deep in holes 1.5 inches (38.1 mm) in diameter and spaced 9 inches (228.6

mm) from each adjacent anchor to form a square.















CHAPTER 5
IMPLEMENTATION OF TEST PROGRAM

5.1 General

This test program consisted of two concrete pours and three sets of anchor

installations. All tests were unconfined tension tests and performed in general

accordance with applicable sections of ASTM E 488-96 (ASTM 2001d) and ASTM E

1512-01 (ASTM 2001e). General test methods for single and group post-installed and

cast-in-place anchorage systems are presented in ASTM E 488. More specific testing

procedures for bonded anchors are addressed in ASTM E 1512.

5.2 Concrete

For both pours, concrete was ordered from a local ready-mixed plant that batched,

mixed, and delivered the concrete to the University of Florida Structures Laboratory.

The first pour occurred on February 22, 2002; the second pour occurred on July 18, 2002.

All concrete was FDOT Class II to achieve the compressive strengths necessary to

preclude a concrete cone breakout failure. The mix design specified a 28-day

compressive strength of 3400 psi, but cylinder tests yielded a compressive strength of

6460 to 7670 psi. Wooden formwork was utilized to construct the seven rectangular

blocks in each pour: six blocks 4x4x1.25 feet (1219x1219x381 mm) and one block

4x8x1.25 feet (1219x2438x381 mm). Each block contained a single steel reinforcing mat

to accommodate handling stresses and prevent cracking. The reinforcement was located

9 inches (228.6 mm) down from the top surface of the concrete. This distance was

greater than the embedment depth of the anchors, which avoided any interactions during









testing and failure. After the concrete was poured, consolidated, and smoothed, the

blocks were covered with plastic sheets for three days to cure; the blocks were then

removed from the formwork. Blocks were allowed to sit for a minimum of 28 days after

pouring to attain adequate strength before drilling holes. Concrete compressive strength

was determined through cylinder tests performed in accordance with ASTM C 39-01

(ASTM 2001a).

5.3 Specimen Preparation

Once the concrete had sufficiently cured, the required holes for the anchors were

drilled into the concrete blocks by using either a core drill or a hammer drill. The holes

were drilled deeper than the desired embedment depth to provide room for the nut, the

end of the anchor, and a pocket of grout at the base of each hole. A summary of the

dimensions, hole drilling technique, type of anchor installed, and the type of test being

performed can be found in Table 5-1.

After the completion of hole drilling, the holes were cleaned according to the

grout manufacturer's directions. This was accomplished by first vacuuming out the loose

matter resulting from the drilling process. Next, the holes were flushed several times

with clean water, and the water was vacuumed out each time. The holes were then

brushed, while damp, using a bottlebrush in accordance with the grout manufacturer's

directions. The holes were flushed several more times with clean water, and the water

was vacuumed out each time. Then the holes were prepared for installation according to

the grout manufacturer's instructions. This consisted of filling the cleaned holes with

water for a minimum of 24 hours to allow for a damp hole installation. The holes were

sealed with duct tape to prevent foreign matter from entering. Just prior to anchor

installation, the duct tape was removed and excess water was vacuumed out. The anchors










were cleaned prior to installation using paint thinner as a degreaser according to the grout

manufacturer's recommendations.

Table 5-1 Summary of testing program for grout product CA


Anchor Hole Embedment Edge S
Installation Tested Spacing # of
tatn Teted Hole Type Diameter Diameter Depth Distance S b #
# Effect s, in (mm) Tests n
d, in (mm) do, in (mm) he, in (mm) c, in (mm)
1 Baseline Core 0.625 (15.9) 1.5 (38.1) 5.0 (127.0) N/A N/A 5
1 Hammer Hammer 0.625 (15.9) 1.5(38.1) 5.0(127.0) N/A N/A 5
1 Group Core 0.625 (15.9) 1.5(38.1) 5.0(127.0) N/A 5.0 (127.0) 3
2 Baseline Core 0.750 (19.1) 1.5 (38.1) 5.0 (127.0) N/A N/A 3
2 Hammer Hammer 0.750 (19.1) 1.5(38.1) 5.0(127.0) N/A N/A 3
2 Edge Core 0.750 (19.1) 1.5 (38.1) 5.0(127.0) 7.5 (190.5) N/A 5
3 Baseline Core 0.750 (19.1) 1.5 (38.1) 5.0 (127.0) N/A N/A 3
3 Edge Core 0.750 (19.1) 1.5(38.1) 5. (127.0) 4.5(114.3) N/A 5
3 Edge Core 0.750 (19.1) 1.5 (38.1) 5.0 (127.0) 6.0 (152.4) N/A 5
3 Group Core 0.750 (19.1) 1.5(38.1) 5.0(127.0) N/A 9.0 (128.6) 3

a Edge distances designated as N/A refer to anchors installed at > 8do.
b Spacing between anchors designated as N/A refers to anchors installed at > 16do.

5.4 Installation Procedure

Three separate anchor installations were performed at the University of Florida

Structures Laboratory in 2002. All installations were conducted similarly, and grout

cubes were also cast whenever anchors were installed. The compressive strength of the

grout product was determined through the testing of grout cubes in accordance to ASTM

C 109-99 (ASTM 2001b). The holes were filled approximately 75% full, and the headed

anchors were inserted. The anchors were shifted about in the holes to remove any

entrapped air and then supported in position at the proper embedment depth. Moist

curing occurred for seven days by wrapping the anchors with saturated paper towels and

covering the slabs with plastic sheets to retain the moisture.

For the first installation, a field representative from the grout manufacturer was on

site to oversee, train, and assist in the installation process. This ensured that the grout









was proportioned, mixed, and installed to the manufacturer's specifications. For all

installations, the grout product CA was mixed to a fluid consistency with a high torque

electric drill and mixing paddle for five minutes. The grout mixture was then subjected

to a standard 1725 mL flow cone test in accordance with ASTM C 939-97 (ASTM

2001d). The grout product, date of installation, flow rate, and minimum cure time from

all three installations are summarized in Table 5-2. The flow rates fell within the

manufacturer's requirements of 25 to 30 seconds with a tolerance of + 1 second.

Table 5-2 Grout installation summary

Inst n # Date of t P t Flow Rate Minimum Grout Cure Time
Installation # Grout Product
Installation (seconds) (days)
1 April 11,2002 CA 31 28
2 July 11, 2002 CA 26 14
3 August 22, 2002 CA 25 14

5.5 Apparatus

A schematic diagram of the equipment used in the tension tests for the single

grouted anchors can be seen in Figure 5-1. The tests performed were unconfined, since

the position of the reactions was in accordance with ASTM E 488. Figure 5-3 shows the

positions of these reactions in relation to the anchor specimen. The equipment setup was

designed to allow direct measurement of the load and displacement of the single anchor

specimens. The test apparatus consisted of the following parts:

Reaction ring (Diameter > 4hf )

Two steel wide range flange section

Three steel bearing plates for center apparatus

One 120 kip (534 kN) hydraulic ram

One 200 kip (890 kN) load cell









One 1.125 inch (28.6 mm) diameter pull bar/coupling rod and

retaining nut

Coupling nut

Steel plate for Linear Variable Differential Transformers

(LVDT's)

Two LVDT's (2 inch range)

The edge distance tests used two steel channels instead of the reaction ring due to the

anchor proximity to one edge of the concrete block.

The equipment used in the group grouted anchor tension tests is shown in the

schematic diagram in Figure 5-2. These tests were also unconfined due to the position of

the reactions as shown in Figure 5-3. The equipment setup was designed to allow direct

measurement of the load and displacement for each individual anchor as well as the

whole group. The test apparatus consisted of the following parts:

Reaction ring (Diameter > 4he + s)

Two steel wide range flange section

Two steel channels

Three steel bearing plates for center apparatus

One pull plate 12x12x2 inches (304.8x304.8x50.8 mm)

One 120 kip (534 kN) hydraulic ram

One 200 kip (890 kN) load cell

Four 100 kip (445 kN) load washers

One 1.125 inch (28.6 mm) diameter pull bar/coupling rod and

retaining nut









Four steel angles

Two steel frames for potentiometers

Four steel bearing plates for single anchors

Four potentiometers (1.5 inch range)

C-Clamps of various sizes


S Pill Rar

Load Cell


Hydraulic Ram
I I
Coupling Nut
S- LVDT


LVDT Plate

Test Anchor Reaction Ring

Concrete Block
Grout Layer --a







5.6 Loading Procedure

To pull out a single grouted anchor, the anchor was connected to the coupling rod

using a coupling nut. The reaction ring/steel channels and steel flanges were arranged to

provide an unconfined test surface. The hydraulic ram was placed atop these supports so

that the pull rod passed through its center. The load cell was placed between two bearing

plates above the hydraulic ram. Finally, a retaining nut was tightened down the coupling

rod to the topmost bearing plate, and the LVDT's were secured in position.










Pull Bar


Concrete
Block


Figure 5-2 Group anchor test apparatus



action d Reaction


^2 hef


A-^^


2 hrf


Figure 5-3 Minimum reaction positions of test apparatus for headed anchors


SLoad Cell

SHydraulic
Ram


Steel
Channel






- Load
Washer

- Steel Pull
Plate


R









The hydraulic ram was powered and advanced using a 10,000 psi (68,950 MPa)

electric pump. The pump was outfitted with two valves. The first controlled the supply

to the ram from the pump. The other regulated a bypass from the ram to the oil reservoir.

These valves were manually adjusted to control the load applied to the anchor specimen.

This setup was used in tandem with a data acquisition system capable of continuously

measuring and recording the load and displacement readings.

The typical single anchor testing procedure contained the following steps:

1. Assembling the test apparatus as described above

2. Start data acquisition and LabVIEW software (NI 1999)

3. Adjust the LVDT's to be in range

4. Start pump and pull out anchor

5. Stop test and disassemble apparatus

The loading procedure for the group tests was similar to the single anchor tests.

Each anchor passed through holes in the pull plate, and the coupling rod passed through

the center hole and was secured with a nut. A load washer was placed on top of each

anchor and secured with a bearing plate and a nut. The rest of the test apparatus was

assembled as shown in Figure 5-2. The hydraulic ram was operated in the same manner

as in the single anchor tests. The data acquisition program was also similar but modified

to record the readings from the main load cell, the four load washers, and the four

potentiometers.

The typical group anchor testing procedure contained the following steps:

1. Assembling the test apparatus as described above

2. Start data acquisition and LabVIEW software (NI 1999)









3. Adjust the potentiometers to be in range

4. Start pump and pull out anchor

5. Stop test and disassemble apparatus

5.7 Data Reduction

5.7.1 Displacement Calculations for Single Anchor Tests

Single anchor specimens were located directly under the coupling rod. Two

LVDT's were used to measure displacement readings. The displacement of a single

anchor during testing was calculated by taking the mean of these two readings.

5.7.2 Displacement Calculations for Group Anchor Tests

For each test conducted, the potentiometers were placed at the same location on

the pull plate. This position was 5 inches (127 mm) measured from the center of the pull

plate through the center of the sides and 7.07 inches (179.6 mm) measured from the

center of the pull plate through the corners. Thus, the potentiometers formed a square 10

inches (254 mm) on each side.

All anchor displacements were calculated assuming that the pull plate was rigid.

The deflection of each anchor relative to the concrete block was found using

displacement readings and the geometry of the test setup.

The overall displacement of the group was computed as the mean of the four

potentiometers:


(dI, + d2 + d3 + d4) (7)
dtot =(3 d (inches or mm) (7)
4


The displacement of the single anchors within the group was calculated according

to the test geometry as shown in Figure 5-4:













Pull Rod




Steel Pull Plate -


Test Anchor


7.07 inches


Potentiometer


Figure 5-4 Diagram of displacement calculation for individual anchor in group test


d, = dto + (don (inches)
7.07


tdn,poten -d"totP )
d = do,, + (d-poten- d (mm)
179.6


(8a)


(8b)















CHAPTER 6
TEST RESULTS

6.1 General

The following sections provide a summary of all test series performed. All tests

were performed using the same cementitious grout product, CA. A total of three

installations were performed. All anchors were post-installed as headed with an effective

embedment depth of 5 inches. Appendix B provides the load-displacement graphs and

detailed results for baseline and hole drilling technique anchor tests. The load-

displacement graphs and detailed results for anchors installed near one edge are presented

in Appendix C. Finally, Appendix D contains the load-displacement graphs and detailed

results for the quadruple fastener group anchor tests.

6.2 Single Grouted Anchor Test Results

Three types of single anchor tests were performed. First, baseline anchors were

installed in core-drilled holes. Second, anchors testing the effects of hole drilling

technique were installed in hammer-drilled holes. Finally, anchors were installed in core-

drilled holes at various distances from one edge of the concrete block and subsequently

tested.

Table 6-1 provides a summary of the test results for each type of single anchor

test performed that resulted in bond failure (i.e. tests exhibiting steel failure are excluded

from Table 6-1). In general, single anchors experienced a failure at the grout/concrete

interface accompanied frequently by the formation of a shallow secondary concrete cone

as evidenced by the diagonal cracking that was observed in the concrete after testing.









Frequently, this secondary concrete cone did not remain attached to the anchor during the

tension tests, and cracking and spelling of the concrete was observed on the surface of the

concrete block in addition to the internal diagonal cracks aforementioned. Photographs

of representative failed specimen are contained in Appendix E.

Table 6-1 Summary of single anchor test results exhibiting bond failure

Tested # of Tests in
Installation# TestSeries ted No kips (kN) Abond in2 (mm2) TO psi (MPa) COV # of Tests in
Installation # Test Effect Calculation
1 CD 1 Baseline 29.4 (131) 23.6 (15200) 1250 (8.60) 0.046 5
1 HD 1 Hammer 30.3 (135) 23.6 (15200) 1290 (8.90) 0.012 2
2 CD 2 Baseline 35.1 (156) 23.6 (15200) 1490 (10.3) 0.040 3
2 HD 2 Hammer 29.0 (129) 23.6 (15200) 1230 (8.50) 0.326 3
2 E 7.5 Edge 7.5 31.9(142) 23.6 (15200) 1350(9.30) 0.099 5
3 CD 3 Baseline 39.3 (175) 23.6 (15200) 1670 (11.5) 0.097 3
3 E 4.5 Edge 4.5 28.7 (128) 23.6 (15200) 1220 (8.40) 0.086 5
3 E 6.0 Edge 6.0 32.5 (145) 23.6 (15200) 1380 (9.50) 0.070 5

For the first installation, the average bond stress for the baseline series of core-

drilled holes was 1250 psi (8.60 MPa) with a coefficient of variation of 0.046. For the

test series containing hammer-drilled holes, three of the specimens experienced a steel

failure at a level below the ultimate anchor stress capacity specified by the manufacturer.

The average bond stress for the remaining two specimens installed in hammer-drilled

holes was 1290 psi (8.90 MPa) with a coefficient of variation of 0.012. Normalizing the

mean of the hammer-drilled series with the mean of the baseline series yields a ratio of

1.03 times the baseline series bond stress.

In the second installation, the average bond stress for the baseline series of core-

drilled holes was 1490 psi (10.3 MPa) with a coefficient of variation of 0.040. Anchors

installed in hammer-drilled holes were also tested and resulted in an average bond stress

of 1230 psi (8.50 MPa) and a coefficient of variation of 0.326. Normalizing the mean of

the hammer-drilled series with the mean of the baseline series yields a ratio of 0.826









times the baseline series bond stress. Anchors were also tested for edge effects in the

second installation. The average bond stress for anchors installed in core-drilled holes

7.5 inches away from one edge was 1350 psi (9.30 MPa) with a coefficient of variation of

0.099. Normalizing the mean of the edge distance series with the mean of the baseline

series yields a ratio of 0.909 times the baseline series bond stress.

Baseline anchors, as well as those installed near one edge, were tested in the third

installation. The average bond stress for the baseline series of anchors installed in core-

drilled holes was 1670 psi (11.5 MPa) with a coefficient of variation of 0.097. Anchors

installed in core-drilled holes 4.5 inches away from one edge had an average bond stress

of 1220 psi (8.40 MPa) with a coefficient of variation of 0.086. Normalizing the mean of

the edge distance series with the mean of the baseline series yields a ratio of 0.730 times

the baseline series bond stress. Finally, the average bond stress of anchors installed in

core-drilled holes 6.0 inches away from one edge was 1380 psi (9.50 MPa) with a

coefficient of variation of 0.0700. Normalizing the mean of the edge distance series with

the mean of the baseline series yields a ratio of 0.827 times the baseline series of the bond

stress.

For further comparison, all 11 baseline test results from the three installations

were combined into one database. The average bond stress was 1390 psi (9.60 MPa)

with a coefficient of variation of 0.192. The coefficient of variation is less than 0.200,

which generally indicates that the grout product's behavior is reasonably consistent when

repeated in the given application. FDOT Section 937 (FDOT 2002a) limits the

coefficient of variation for uniform bond stress to 20%, which serves as a basis for using









this limit for the purposes of this paper. Table 6-2 provides a summary of the tests

performed to establish To for grout product CA in the current paper.

Table 6-2 Summary of baseline single anchor test results

Installation # No kips (kN) To psi (MPa) COV n
1 29.4 (131) 1250 (8.60) 0.046 5
2 35.1(156) 1490 (10.3) 0.040 3
3 39.3 (175) 1670 (11.5) 0.097 3
All 32.7 (145) 1390 (9.58) 0.192 11

6.3 Group Grouted Anchor Test Results

Two sets of quadruple fastener group anchor test series were installed and tested.

All anchors were installed in core-drilled holes. All parameters, except anchor spacing,

were held constant. Table 6-3 provides a summary of the group test series results.

In the first anchor installation, groups of grouted anchors were installed in core-

drilled holes with an anchor spacing of 5 inches. All of the repetitions in this test series

experienced a concrete cone breakout failure. Due to this, an average bond stress could

not be calculated. The average total tensile failure load was 64.1 kips (285 kN) with a

coefficient of variation of 0.040. According to the CCD method shown in Equation (2),

the predicted strength of the grouted anchor groups with anchor spacing of 5 inches was

69.6 kips.

Groups of grouted anchors were also installed in core-drilled holes in the third

installation. In this test series, the anchor spacing was increased to 9 inches. All of the

repetitions in this test series exhibited a bond failure at the grout/concrete interface. The

average total tensile failure load was 104 kips (460 kN) with a coefficient of variation of

0.027. The average bond stress of the anchor group was 1100 psi (7.60 MPa). The

predicted strength of the grouted anchor groups using the diameter of the hole in the










uniform bond stress model was 74.4 kips. This value is conservative, and a revision to

the critical spacing will be presented in the proposed design model in Chapter 8.

Table 6-3 Summary of multiple anchor test results

Tested Group in Failure
Installation # Effect Series f at test psi (MPa) FaModei Ntet kips (kN) to,test psi (MPa)

1 G 5.0 1 7670 (52.9) cone 63.4 (282) NA

1 G 5.0 2 7670 (52.9) cone 66.9 (298) NA

1 G 5.0 3 7670 (52.9) cone 62.0 (276) NA


N 64.1 (285)


COV 0.040


3 G 9.0 1 7330 (50.5) g/c 105 (465) 1110(7.65)

3 G 9.0 2 7330 (50.5) g/c 106 (469) 1119(7.72)

3 G 9.0 3 7330 (50.5) g/c 100 (446) 1065 (7.34)


N 104 (460)


COV 0.027


a Tests in which a failure at the grout/concrete interface occurred are designated as g/c.















CHAPTER 7
TESTED FACTORS INFLUENCING GROUT BOND STRENGTH

7.1 General

Grouted anchor performance can be influenced by a wide variety of factors

ranging from grout properties, to installation conditions, to loading and environmental

conditions while in-service. It is important to understand the effects that various

conditions have on grout bond strength to enable proper design of a structure. Testing of

a variety of potential effects were performed over the course of several grouted anchor

testing programs with the purpose of determining what types of product approval tests

might apply to engineered grout products. The following is a written summary of these

results. Graphical representations of these results can be found in Appendix F.

7.2 Strength versus Curing Time

Kornreich (2001) performed tests on unheaded threaded rods installed using three

different grout products: one polymer (PB) and two cementitious (CA and CG) grouts.

Tests were performed at 24 hours, 3 days, 7 days, 14 days, and 28 days. The rate at

which the grouts attained their full bond strength appeared to be product dependent.

However, the polymer based grout product seemed to reach its full bond strength in a

shorter time period; product PB appeared to reach full strength after only 24 hours. Grout

CG matured to full strength after 7 days, and grout CA did not attain full strength until 14

days after installation. Currently, FM 5-568 (FDOT 2000) only requires a short-term

cure test for adhesive anchors in which tests are performed at only 24 hours.










7.3 Threaded Rod versus Deformed Reinforcing Bar

Zamora (1998) performed tests to investigate the potential differences between

the grout bond strength of unheaded threaded rods and deformed reinforcing bars. Four

cementitious grout products were examined. Three of the four products experienced a

lower bond strength when the grout was installed with a deformed reinforcing bar. Two

of these showed small decreases; products CB and CF experienced a reduction in bond

strength of 9% and 4%, respectively. However, the bond strength of product CD

diminished by 27%. The fourth product, CC, showed a 104% increase in bond strength

when installed with deformed reinforcing bars. However, this product is no longer

marketed for this application and should not be used to draw conclusions. The effect on

bond strength appears to be product dependent, and products should be tested to observe

if a significant strength variation, defined as over 20% for the purposes of this paper,

occurs. This limit on bond strength variation is similar to the limit set forth in ICBO ES

AC58 (ICBO ES 2001) for variation between strengths obtained from testing anchors

installed in damp holes and in baseline dry holes.

7.4 Threaded Rod versus Smooth Rod

Kornreich (2001) compared the bond strength of grouts for unheaded threaded

rods and unheaded smooth rods for both cementitious and polymer grout products. For

all three products tested, the bond strength for smooth rods was lower than that for

threaded rods. However, the amount of bond strength reduction seemed dependent on the

type of grout product installed. Grout products CA and CG experienced an 91% and a

81% reduction in bond strength, respectively. The polymer grout product tested, PB,

exhibited a 53% decrease in bond strength. All of these reductions in bond strength are









sufficiently large such that it is recommended that unheaded smooth rods should not be

relied upon in tension.

7.5 Regular Hex Nut versus Heavy Hex Nut

Zamora (1998) performed a test series to examine the possible effects that the use

of various types of nuts in headed anchor applications have on pullout resistance. The

study found that a difference in pullout resistances existed depending on the type of nut

that was used.

The pullout resistance of anchors installed with cementitious grouts decreased

when a heavy hex nut was used. Products CA, CB, and CC demonstrated a reduction in

pullout resistance of 15%, 19%, and 8%, respectively, when installed with a heavy hex

nut. Contrastingly, the pullout resistance increased by 10% when anchors were installed

using polymer grout product PA and a heavy hex nut instead of a regular hex nut. Since

only one polymer grout product was tested, it is unclear if all polymer grouts behave in a

similar manner. When installed with a regular hex nut, products CA, CB, CC, and PA

exhibited a coefficient of variation of 0.052, 0.136, 0.070, and 0.066, respectively.

Products CA, CB, CC, and PA had a coefficient of variation of 0.124, 0.150, 0.093, and

0.034, respectively, when a heavy hex nut was used for installation. The change in

pullout resistance appears to be dependent on the grout product used. However, when the

regular hex nut and heavy hex nut tests are considered in tandem for each product, the

coefficients of variation are 0.126, 0.187, 0.086, and 0.058 for products CA, CB, CC, and

PA, respectively. These coefficients of variation are not significant as they are less than

20%, and, therefore, it seems that it is unnecessary to test products using different types

of nuts.









7.6 Hole Drilling Technique

Two test series comparing headed anchors installed in hammer-drilled holes to

those installed in core-drilled holes were performed in the testing program of the current

paper. In one test series, there was essentially no difference between the bond strength of

anchors installed in the two types of holes. When anchors were installed in hammer-

drilled holes, the bond strength increased by 3% with a coefficient of variation of 0.012.

A subsequent test series examined the same grout product, CA. It was found that the

results of anchors installed in hammer-drilled holes were widely scattered with a

coefficient of variation of 0.326, and the average bond strength was 17% lower than the

bond strength of the baseline anchors installed in core-drilled holes. Combining the

results of both test series yielded a coefficient of variation of 0.244. These tests from

different installations could be considered together since each series was normalized with

respect to the baseline series of that installation.

It is possible that when the holes were hammer-drilled the pores in the concrete

became filled with dust from the drilling process. The presence of this dust could have

prevented the grout product from fully bonding to the concrete even though the cleaning

procedures recommended by the manufacturer were performed. This could account for

the scatter observed in one of the two installations. It is recommended that tests be

performed on cementitious grouts to determine if sensitivity to hole drilling technique

exists whenever they are to be installed in holes drilled in a manner other than that

recommended by the manufacturer.

7.7 Damp Hole Installation

This test series consisted of anchors installed in damp holes free of standing

water. Zamora (1998) tested three polymer grouts: PA, PB, and PC. Two of the products









had a noticeable bond strength reduction when installed in damp holes rather than dry

holes. Product PB experienced a 17% strength reduction, and product PC exhibited a

27% decrease in bond strength. A third product, PA, experienced a bond strength

increase 11%. The effect of a damp hole installation on bond strength seems significant

and product dependent. Therefore, polymer grout products should be tested for the

effects of this variable on bond strength.

7.8 Elevated Temperature

Anchors installed with polymer grouts are believed to be more sensitive to

temperature variations than cementitious products. Zamora (1998) tested two polymer

grouts, PA and PB, at elevated temperatures and found a reduction in bond strength of

6% for both products when compared to those tested at ambient temperature. It appears

that the bond strengths of these two products are not greatly influenced by elevated

temperatures.

However, Cook and Konz (2001) performed similar elevated temperature

sensitivity tests on 15 adhesive products. Of the 15 products tested, ten exhibited a bond

strength variation of greater than 20%. Adhesive products consist of two components: a

resin and a hardener. Polymer grouts contain similar components as adhesives with a

filler for the additional third component. Since adhesive products are strongly influenced

by elevated temperatures and polymer grout products are similar in composition, it is

important to test polymer grout products being for sensitivity to elevated temperature.

7.9 Summary

Previous testing programs, as well as the current testing program, have tested the

bond strength sensitivity of various grouts to several installation conditions. The effects

of strength versus curing time, threaded rod versus deformed reinforcing bar for










cementitious grouts, threaded rod versus smooth bar, varying types of nuts on headed

anchors, hole drilling technique for cementitious grouts, damp hole installation for

polymer grouts, and elevated temperature were tested for polymer grouts. Table 7-1

provides a brief summary of the tested variable of interest, the type of grout product

installed, and a short explanation of the results of testing.

Table 7-1 Summary of tested factors influencing grout bond strength


Test Grout Type
Cementitious Polymer
Effect appears product
Strength vs. Curing Time dependent; generally One product tested
slower than polymer
Threaded Rod vs. Deformed Effect appears product Not tested
Not tested
Reinforcing Bar dependent
Large reduction in bond
Large reduo in bd Reduction in bond strength; one
Threaded Rod vs. Smooth Bar strength for both products p t
tested product tested
tested
Reduction in pullout
Reduction in pullout Increase in pullout resistance for
Regular Hex Nut vs. Heavy resistance for heavy hex; heavy hex; unclear if this is a general
heavy hex; unclear if this is a general
Hex Nut amount appears product p
depe pattern for polymer products
dependent
Effect is not consistent
Hole Drilling Technique and results are at times Not tested
widely scattered
Damp Hole Installation Not tested Effect appears product dependent
Elevated Temperature Not tested Reduction in bond strength















CHAPTER 8
DISCUSSION ON DESIGN METHOD FOR GROUTED ANCHORS

8.1 Current Models

Previous studies have developed design models for adhesive anchors as well as

cast-in-place anchors. Cook et al. (1998) found the uniform bond stress model to be an

adequate predictor of adhesive anchor behavior. Similarly, Fuchs et al. (1995) found that

the strength of cast-in-place anchors can be accurately predicted using the CCD method.

Equations describing the uniform bond stress model and the CCD method are shown in

Chapter 3. Modification factors can be applied to both models to account for anchors

near a free edge or spaced close enough to act as an anchor group.

8.2 Predicted Model for Grouted Anchor Behavior

Grouted anchors can experience one of three different embedment failure modes:

failure at the steel/grout interface, failure at the grout/concrete interface, or concrete cone

breakout failure. Steel failure may also occur. The embedment failure mode and strength

can be predicted from equations that represent the behavior of each failure mode. The

lowest of these predicted strengths indicates the expected failure mode unless this failure

mode is prevented by physical constraints of the anchor configuration. For example,

failure at the steel/grout interface is not possible if a headed anchor is utilized.

As previously mentioned, equations to predict anchor strength when failure

occurs from a concrete cone breakout or at the steel/grout interface have undergone

extensive testing. Zamora (1998) proposed using the hole diameter instead of the anchor

diameter in the uniform bond stress model to predict anchor strength when failure occurs









at the grout/concrete interface. This substitution was shown previously in Equation (4).

Using the failure load obtained from testing, the bond stress, To, can be calculated.

Anchors in the current test program were designed to exhibit a failure at the

grout/concrete interface. It was predicted that the bond strength would correspond to the

failure load calculated using the hole diameter in the uniform bond stress model.

Therefore, the critical edge distance was expected to be 8do, and the critical spacing

between adjacent anchors was anticipated to be 16do as shown previously in Figure 3-6.

However, Figures 8-1 and 8-2 show that the coefficients of 8 and 16 are overly

conservative for predicting the mean anchor bond strength for anchors installed near a

free edge and in fastener groups, respectively. Figure 8-1 depicts a plot of the normalized

anchor strength versus edge distance. To normalize, the test result and the predictive

curve were divided by the predicted strength of a single anchor installed away from an

edge and surrounding anchors. Figure 8-2 presents a graph of the normalized anchor

group strength versus anchor spacing. The test result and predictive curve were divided

by four times the predicted strength of a single anchor installed away from an edge and

surrounding anchors to normalize. Therefore, the behavior of grouted anchors

experiencing a bond failure at the grout/concrete interface can be better represented if the

critical edge and spacing distances are revised.

The following sections provide recommended equations and modification factors

for determining the design strength of single grouted anchors and groups of grouted

fasteners in uncracked concrete using Load and Resistance Factor Design (LRFD).

8.3 Proposed Critical Edge Distance and Critical Anchor Spacing Revision

Different values for the critical edge distance and anchor spacing were considered

by graphically fitting design equations to the test data. It was assumed that the critical











1.5





'o0
1

s

I -

o 0.5
z


2 4 6 8 10 12
Edge Distance (inches)


Figure 8-1 Critical edge distance of 8do compared to experimental results


0 2 4 6 8 10 12
Anchor Spacing (inches)


Figure 8-2 Critical anchor spacing of 16do compared to experimental results

anchor spacing is twice the critical edge distance, similar to the existing uniform bond

stress model. The values chosen to best fit the experimental data of the current paper's


0
o 8

o 8 8 --/
8

K \ Equation
(6) with
single
anchor


8




Equation
S(6) with
anchor
group










test program were 5do for the critical edge distance and 10do for the critical spacing

between anchors. Figures 8-3 and 8-4 display how these new coefficients more

accurately predict the mean failure loads obtained during testing and are normalized as

discussed in the previous section for Figures 8-1 and 8-2. In Figure 8-4, the proposed

equation predicts a higher strength for bond failure at the grout/concrete interface than

that found from testing when the anchor spacing equals 5 inches. This was as expected

since the failure mode observed during testing was a concrete cone breakout which

occurred at a lower load than a failure at the grout/concrete interface.

15-
/
/
/
/

s o/
S8 8
< O-

05





0 2 4 6 8 10 12
Edge Distance (inches)


Figure 8-3 Critical edge distance of 5do compared to experimental results

8.4 Proposed Model for Single Grouted Anchors

For single unheaded grouted anchors, it is recommended that the design strength

be taken as the smaller of the bond strengths calculated at the steel/grout interface and at

the grout/concrete interface using Equation (9) and Equation (10), respectively. The

following design equations are based on the uniform bond stress model and a 5% fractile.














0.8



0.6



I 0.4



0.2



0
0 2 4 6 8 10 12
Anchor Spacing (inches)



Figure 8-4 Critical anchor spacing of 10do compared to experimental results



b oN'To = b( ,e 'C dh,) (lbforN) (9)




bN',O = b (,Toe T ''o do hf) (lbforN)
(10)
where T' = 0.7 + 0.3 -
,e 5d



For single headed grouted anchors, it is recommended that the design strength be

taken as the smaller of the bond strength calculated at the grout/concrete interface and the

concrete cone breakout strength using Equations (10) and (1 la or 1 Ib), respectively. The

following design equations are based on the CCD model and a 5% fractile.



c oN'c,o =Jc(Wce30 fhe5) (lbf) (lla)

or










o=N',= c(W 12.6 f7hef5) (N) ( lb)


8.5 Proposed Design Model for Grouted Anchor Groups

For groups of unheaded grouted fasteners, it is recommended that the design

strength be taken as the smaller of the bond strengths calculated at the steel/grout

interface and at the grout/concrete interface using Equations (12) and (13), respectively.

The following design equations are based on the uniform bond stress model and a 5%

fractile.



bN', =kb(A N'NTO) (lbforN) (12)
ANO




bN'0 = ( A N ,0) (lbforN) (13)



For groups of headed grouted anchors, it is recommended that the design strength

be taken as the smaller of the bond strength calculated at the grout/concrete interface and

the concrete cone breakout strength using Equations (13) and (14), respectively. The

following design equation is based on the CCD model and a 5% fractile.



cN'cone = c ( -N',0 ) (lbf or N) (14)
ANO


In Equations (12 and 14), AN and ANO are calculated as shown in Figures 3-4 and 3-2,

respectively. In Equation (13), AN and ANO are calculated as shown in Figure 3-6 except

using a critical edge distance of 5do and a critical anchor spacing of 10do.















CHAPTER 9
DISCUSSION ON PROPOSED PRODUCT APPROVAL TESTS

9.1 General

A good grout product will possess the following desirable qualities:

flowability for ease of placement and sufficient working time

low sensitivity to hole drilling technique

low sensitivity to hole cleaning technique

low sensitivity to moisture condition of hole

low sensitivity to temperature differentials

rapid development of bond strength

consistent bond strength when installed using various types of

anchors

The following sections present the proposed product approval tests to evaluate

engineered grout products. In all of the following, the maximum coefficient of variation

is limited to 20% unless otherwise stated by the Engineer for the given application. This

is similar to the aforementioned limit placed on the coefficient of variation for uniform

bond stress in FDOT Section 937 (FDOT 2002a) for adhesives. As mentioned in Section

7.3, the level that constitutes a significant change in bond strength is 20% for the

purposes of this paper. Additionally, in all sections a minimum of five repetitions should

be performed in accordance with ASTM E 488 (ASTM 2001d). When only steel failure

occurs, ASTM E 488 requires a minimum of three repetitions.










9.2 Grout/Concrete Bond Stress (To)

This proposed product approval test allows the grout/concrete bond stress (To) to

be determined for a given grout product. This value can be calculated from the anchor

strength if a bond failure occurs at the grout/concrete interface. Failure at the

grout/concrete interface is a failure mode that occurs infrequently, but test parameters can

be configured to force this failure mode to occur. This failure mode can be achieved by

using a headed anchor to preclude failure at the steel/grout interface and minimizing the

hole diameter. Additionally, a bond failure at the grout/concrete interface can be

achieved by using a higher strength concrete such that the tensile capacity associated with

a grout/concrete bond failure will be less than the breakout capacity of the concrete. All

anchors shall be installed per manufacturer instructions using a 0.75 inch diameter anchor

headed with a heavy hex nut and installed in a 1.5 inch diameter hole with an embedment

length of 5 inches measured from the top of the nut. Once To is determined for a grout

product, it can be used in calculations for predicting the strength of various anchor

configurations such as edge distance and group tests.

9.3 Test Series to Establish Steel/Grout Bond Stress (c)

This test series allows the steel/grout bond stress (c) to be determined for a given

grout product. This value can be calculated from the bond strength if a failure is forced at

the steel/grout interface. This failure mode can be initiated by using unheaded anchors

installed in concrete whose breakout capacity is greater than the bond capacity of the

grout product. All anchors shall be installed in accordance with the manufacturer's

instructions and as unheaded to promote a failure at the steel/grout interface. All anchors

shall be installed per manufacturer instructions using a 0.75 inch diameter unheaded









anchor installed in a 1.5 inch diameter hole with an embedment length of 5 inches

measured from the base of the anchor. Once c has been determined for a grout product, it

can be used in subsequent strength prediction calculations.

9.4 Strength versus Curing Time

In certain scenarios, it may be necessary for an anchor to sustain loading a short

time after installation. It is advantageous to know when a product develops sufficient

strength so that premature loading, and the resulting problems, may be avoided. In the

same vein, construction time may be saved if it is known that a particular grout product

achieves sufficient strength in a short amount of time.

Anchors shall be installed according to manufacturer directions and as unheaded.

Polymer grouted and quick setting cementitious grouted anchors should be tested at 24

hours and 7 days. Non-quick setting cementitious grouted anchors should be tested at 7

days and 28 days. A minimum of five anchors should be tested at each interval. The

interval at which the bond strength reaches a sufficient value should be noted. This

knowledge can be used in construction scheduling as well as in choosing a grout product

whose strength development fits into a given time frame.

9.5 Threaded Rod versus Deformed Reinforcing Bar

It is important to compare the bond strength a grout product possesses for

threaded rods and deformed reinforcing bars. Both of these materials are commonly

installed in the field, so being able to predict how they will behave while in-service is

imperative. This test program should investigate the performance of unheaded grouted

anchors installed with a threaded rod and compare this behavior to that when a deformed

reinforcing bar is installed. Installation using a threaded rod shall be considered as the

baseline series. Unheaded anchors must be used to try to force a failure at the steel/grout









interface. A failure at this location will allow calculation of the bond stress, c, directly

from the bond strength.

All anchors shall be installed in accordance with the manufacturer's directions

and as unheaded. The resulting bond strengths should be compared. Ideally, the grout

product would exhibit similar bond strengths for both types of anchors. The results from

testing of threaded rods and reinforcing bars should be compared. If the deformed

reinforcing bar average bond strength is more than 20% less than the average bond

strength of threaded rods, or if the coefficient of variation of the deformed reinforcing bar

test series exceeds the aforementioned maximum, the grout product should be limited to

installation with threaded rods.

9.6 Hole Drilling Technique

Anchor test series should include the baseline series of installing headed anchors

in core-drilled holes according to the manufacturer's directions as well as a series of

headed anchors installed per manufacturer instructions except in holes drilled with the

hole drilling technique to be evaluated. In order to evaluate the effect of the hole drilling

technique, a bond failure at the grout/concrete interface must occur. Therefore, all

anchors shall be installed using the type of nut, anchor diameter, hole diameter, and

embedment depth described in Section 9.2. If either the coefficient of variation for the

tested hole drilling technique or the reduction in the bond strength between the baseline

and the variable test series exceed the limit of 20%, the grout product tested should not be

installed in holes drilled using the tested hole drilling technique.

9.7 Moisture Condition of Hole

Bond strength can be influenced by the moisture condition of the hole depending

on the type of grout product used for anchor installation. Cementitious grout products









commonly require installation in damp holes to prevent excessive water loss from the

grout to the concrete, which could reduce the bond strength of the grout. Polymer grouts

are usually installed in dry holes to allow the chemical reactions to occur, thus binding

the grout to the concrete. If a polymer grouted anchor is installed in a damp hole (i.e. a

core-drilled hole that has not been given sufficient time to dry), the presence of water

could impede the bonding process, thus reducing the bond strength. Grout products

being evaluated should be tested for sensitivity to damp or dry hole conditions. In order

to evaluate the effect of the moisture condition of the hole, it is necessary for failure to

occur at the grout/concrete interface. Therefore, all anchors shall be installed using the

type of nut, anchor diameter, hole diameter, and embedment depth described in Section

9.2.

In the damp hole installation test series, polymer grouted anchors should be

installed as headed and according to the manufacturer's instructions, except the holes

shall be damp at the time of installation as described in Section 5.3. Additionally, a

baseline series needs to be installed as per manufacturer instructions. The bond strength

from the baseline series and the damp hole installation series should be compared. ICBO

ES AC58 (ICBO ES 2001) states that all dampness specimen results shall be at least 80%

of the average of the baseline specimens. The appropriate restrictions, if any, should be

assigned to the polymer grout product based on the bond strength results evaluated in

accordance with ICBO ES AC58 and the maximum coefficient of variation as set forth in

this paper.

In the dry hole installation test series, cementitious grouted anchors should be

installed in accordance with the manufacturer's instructions, except the holes shall be dry









at the time of installation. Additionally, a baseline series needs to be installed per

manufacturer instructions. The bond strength from the baseline series and the dry hole

installation series should be compared. Dry specimen shall be considered in a similar

manner to dampness specimen. All dry hole installation specimen results shall be at least

80% of the average of the baseline series. The coefficient of variation of the dry hole

installation series shall be less than the aforementioned maximum. The appropriate

restrictions, if any, should be assigned to the cementitious grout product based on the

bond strength results.

9.8 Elevated Temperature

This parameter is considered more critical for polymer grouts as they are believed

to be more sensitive to temperature changes. Test series of headed and unheaded anchors

installed, cured, and tested at elevated temperature (1100 F; 43.3 C) should be

performed. The anchors should be installed in accordance with the manufacturer's

directions, except at elevated temperature. The bond strengths from each series should

then be compared. The grout product may be approved for use in elevated temperature

applications if the average bond strength at elevated temperature is not more than 20%

less than the bond strength of the baseline series and the coefficient of variation of the

elevated temperature series is less than the limit set forth in this paper.

9.9 Horizontal and Overhead Hole Orientation (Optional)

Bond strength has the potential to be significantly reduced when anchors are

installed at an orientation other than vertically downward. This reduction is due to the

grout settling unevenly or flowing out of the hole. For a horizontal installation, the

anchor is perpendicular to the vertical face of the concrete. The anchor potentially settles

against the lower surface of the hole resulting in a non-uniform grout thickness around









the anchor. Additionally, air voids can form along the upper hole surface. This

diminishes the bond area and thus results in a corresponding reduction in bond strength.

For an overhead orientation, the anchor is installed vertically upward. The grout

wants to flow out of the hole, and the anchor potentially settles in an outward movement.

This settlement can result in a reduction in the effective embedment depth and

corresponding losses of bond area and bond strength.

In order to minimize the punitive effects an alternate hole orientation can have on

bond strength, it is highly recommended that cementitious grouts should not be installed

in this type of application. Non-quick setting cementitious grouts are not sufficiently

viscous, and their initial set time is too long to make their use practical for alternate hole

orientation installations. Similarly, polymer grouts possessing low viscosities should also

not be utilized.

In the optional horizontal hole orientation test series, grouted anchors shall be

installed in accordance with manufacturer directions, except in horizontally oriented

holes. The bond strength from the baseline series installed in vertical holes and

horizontal hole orientation series should be compared. If the bond strength is reduced by

more than the limit set forth in this paper when installed horizontally, or if the coefficient

of the horizontal hole test series exceeds the aforementioned maximum, the grout product

shall be excluded from installation in horizontally oriented holes.

Similar optional tests to those performed on anchors in the horizontal hole

orientation test series should be performed on grouted anchors installed in overhead

holes. This test series should also be compared to the baseline series. Similarly, if the

reduction in bond strength or the coefficient of variation of the overhead test series









exceed the limits set forth in this paper, the grout product shall be excluded from use in

this application.

9.10 Long-term Load (Optional)

Anchors subjected to sustained tension loading may undergo displacements due to

creep. If the rate of displacement does not attenuate, the anchor displacement will reach

unacceptable levels. The variable of interest is the amount of displacement. Therefore,

the applied load should not induce failure. The applied load should be a service level

load that can be taken as a percentage of the tensile load that incites failure. Similar to

FM 5-568 (FDOT 2000), it is recommended that a tensile load that is 40% of the mean

failure load value from the baseline series be used.

This test series is optional unless sustained long-term load is anticipated. Both

headed and unheaded anchors shall be tested. In these test series, anchors should be

installed per the manufacturer's directions. In accordance with FM 5-568, creep tests

shall be performed at elevated temperature.

Displacements should be measured more frequently near the beginning of the

loading period. It is recommended that displacement data should be sampled for a

minimum of 42 days. At the end of 42 days, the load can be removed from the anchors.

In accordance with FDOT Section 937 (FDOT 2002a), the rate of displacement shall

decrease during the 42 day loading period. Also, at the end of the loading period, the

total creep displacement shall be less than 0.03 inch (0.75 mm) and less than 0.003 inch

(0.075 mm) during the last 14 days of loading.

The anchors that have not exceeded the predefined displacement limit should then

be reloaded in tension and tested to failure. The bond strength from these reloaded

anchors should be compared to that of the baseline test series. If the coefficient of









variation or the reduction in bond strength of the creep test series exceed the limits set

forth in this paper, it may be appropriate to limit the use of the product to applications in

which service loads would not need to be sustained long-term. If the level of creep

displacement exceeds the limit, the anchor can be considered to have failed.

9.11 Additional Factors

Other factors may also need to be considered when determining whether a grout

product can be used in a certain application. Some additional factors are: repeated loads,

freezing and thawing cycles, seismic (shear and tension), cracked concrete, and concrete

aggregate. Testing methods for these factors are outside the scope of this report.















CHAPTER 10
SUMMARY, CONCLUSIONS, AND RECOMMENDATIONS

10.1 Summary

This thesis addresses the behavior of headed and unheaded grouted anchors

installed in uncracked concrete tested in tension. Data from this test program as well as a

summary of data from other test programs are presented. A variety of products, anchor

configurations, installation conditions, edge distances, and group anchor spacings have

been tested. Test results were used to establish if existing behavioral models for adhesive

and cast-in-place anchors could be extended to accurately predict the strength of grouted

anchors. These models are the uniform bond stress model and the concrete capacity

design model, respectively. Additionally, factors that constitute a desirable grout product

are discussed. The results from various installation and service condition tests are

analyzed, and product approval tests for grouts are proposed.

10.2 Conclusions

Grouted anchor behavior varies depending on the product used for installation,

whether the anchor is installed as unheaded or headed, installed near an edge, installed in

an anchor group, and what installation and service conditions the anchor is exposed to.

Four different failure modes exist for grouted anchors: bond failure at the steel/grout

interface, bond failure at the grout/concrete interface, concrete breakout failure, and steel

failure. Ignoring steel failure, unheaded grouted anchors predominantly experience a

bond failure at the steel/grout interface, but a bond failure at the grout/concrete interface

has also been observed. Again, ignoring steel failure, headed grouted anchors may









experience either a bond failure at the grout/concrete interface or a concrete cone

breakout.

In general, the capacity of unheaded grouted anchors can be predicted by the

uniform bond stress model (Equations (3) and (5)), which is based on the bond stress (c)

at the steel/grout interface. If the grout/concrete bond stress (To) is low enough, a bond

failure may occur at the grout concrete interface (Equations (4) and (6)). The failure

mode can be predicted based on which equation yields the smaller bond strength. For

design, the expected anchor strength can be taken as the lesser of Equation (9) and

Equation (10).

Bond failure at the steel/grout interface is precluded for headed grouted anchors

by the presence of the head. The capacity of headed grouted anchors can be predicted by

either the uniform bond stress model (Equations (4) and (6)) or the concrete capacity

design model (Equations (la or lb) and (2)). The failure mode can be predicted by which

of these two models yields the lower result. For design, the expected anchor strength can

be taken as the lesser of Equation (10) and Equations (1 la or 1 Ib).

The test program reported in this thesis indicated that the critical edge distance

and critical anchor spacing of the uniform bond stress model currently used for adhesive

anchors were not accurate for grouted anchors. The data were analyzed, and the critical

edge distance for grouted anchors was found to be 5do; the critical anchor spacing for

grouted anchors was found to be 10do.

This report includes an analysis of tests of installation and service conditions.

The tests performed in the current test program and in previous testing programs led to

the following conclusions:









Products develop strength at different rates. In general, polymer

grouts develop a significant portion of strength more rapidly than

cementitious grouts.

The type of grout product used to install the anchor can greatly

influence the anchor strength. Unheaded smooth rods should not

be relied upon in tension.

Headed grouted anchors are not sensitive to the type of nut (regular

hex or heavy hex) used on the embedded end during installation.

The moisture condition of the hole affects the bond strength of

anchors installed with polymer grouts, and it is conjectured that

cementitious grouts can also be sensitive to the moisture condition

of the hole.

Polymer grouts are believed to be sensitive to elevated

temperatures since they are similar in composition to adhesives,

which have been shown to possess this sensitivity.

10.3 Recommendations

Based on the test results presented in this thesis, the following tests are proposed

to establish grout product properties and sensitivities:

Establish Co.

Establish T.

Establish strength development curve.

Compare threaded rod versus deformed reinforcing bar.

Evaluate sensitivity to hole drilling technique.









Evaluate sensitivity to moisture condition of hole.

Evaluate sensitivity to elevated temperature.

Additionally, hole orientation and long-term loading (creep) tests are proposed as

optional tests.

A comprehensive design model for grouted anchors is needed, and the CCD

method and modifications to the uniform bond stress model were shown to accurately

predict anchor capacity. It was observed that installation and service conditions will

affect the behavior of grouted anchors, and product approval tests were proposed to

investigate some of these effects. Further testing is recommended to establish safety

factors for the aforementioned installation and service conditions. Future study is

recommended for the following topics not addressed in this paper:

The effect of repeated loads on the performance of grouted

anchors.

The effect of freezing and thawing cycles on the performance of

grouted anchors.

The effects of seismic forces (shear and tension) on the

performance of grouted anchors.

The effect of cracked concrete members on the performance of

grouted anchors.

The effect of various concrete aggregates on the performance of

grouted anchors.















APPENDIX A
NOTATION

c = distance from center of an anchor shaft to the edge of concrete, in (mm).

cl = distance from the center of an anchor shaft to the edge of concrete in one
direction, in (mm).

C2 = distance from the center of an anchor shaft to the edge of concrete in the
direction orthogonal to cl, in (mm).

d = diameter of the anchor, in (mm).

do = diameter of the hole, in (mm).

d, = net potentiometer displacement; subscript ranges from 1 to 4 for quadruple
fastener anchor groups, in (mm).

d, = distance from the surface of the concrete to the bottom of the pull plate at
each anchor in an anchor group; subscript ranges from 1 to 4 for quadruple
fastener anchor groups, in (mm).

dn,poten = distance from the surface of the concrete to the bottom of the pull plate at
each potentiometer in an anchor group; subscript ranges from 1 to 4 for
quadruple fastener anchor groups, in (mm).

dtot = overall displacement of an anchor group, in (mm).

f'c = concrete compressive strength, psi (N/mm2).

hef = effective anchor embedment depth, in (mm).

k = factor based on a 5% fractile, 90% confidence, and number of tests
performed.

n = number of tests performed.

s = anchor center-to-center spacing, in (mm).

sl = anchor center-to-center spacing in one direction, in (mm).









s2 = anchor center-to-center spacing in the direction orthogonal to sl, in (mm).

Abond = bonded surface area between grout and concrete, in2 (mm2).

AN = projected concrete failure area of an anchor or group of anchors, for
calculation of strength in tension, in2 (mm2).

ANO = projected concrete failure area of one anchor, for calculation of strength in
tension when not limited by edge distance or spacing, in2 (mm2).

N = general mean tensile strength for an anchor group with unspecified failure
mode, lbf(N).

No = general mean tensile strength for a single anchor with unspecified failure
mode, lbf(N).

Nc,o = mean tensile strength for concrete cone breakout of a single anchor, lbf (N).

N,o = mean tensile strength for steel/grout failure of a single anchor, lbf (N).

NTo,o = mean tensile strength for grout/concrete failure of a single anchor, lbf (N).

N, = mean tensile strength for concrete cone breakout of an anchor group, lbf (N).

Ntest = tensile strength of a single anchor or an anchor group for one test repetition,
lbf (N).

N, = mean tensile strength for steel/grout failure of an anchor group, lbf (N).

No = mean tensile strength for grout/concrete failure of an anchor group, lbf (N).

N',o = nominal tensile strength for concrete cone breakout of a single anchor, lbf (N).

N',o = nominal tensile strength for steel/grout failure of a single anchor, lbf (N).

N'o,o = nominal tensile strength for grout/concrete failure of a single anchor, lbf (N).

N'cone = nominal tensile strength for concrete cone breakout of an anchor group, lbf
(N).

N', = nominal tensile strength for steel/grout failure of an anchor group, lbf (N).

N',o = nominal tensile strength for grout/concrete failure of an anchor group, lbf (N).

COV = coefficient of variation.









4b = strength reduction factor for bond failure (0.85 is recommended).

kc = strength reduction factor for concrete cone breakout (0.75 is recommended).

T = mean uniform bond stress at the steel/grout interface, psi (MPa).

To = mean uniform bond stress at the grout/concrete interface, psi (MPa).

To,test = uniform bond stress at the grout/concrete interface for a single anchor or an
anchor group in one test repetition, psi (MPa).

T' = 'c(-kCOV), nominal uniform bond stress at the steel/grout interface, psi
(MPa).

c 'o = Tco(-kCOV), nominal uniform bond stress at the grout/concrete interface, psi
(MPa).

P,e = modification factor, for strength in tension, to account for edge distances
when bond failure occurs at the steel/grout interface.

Y P,e = modification factor, for strength in tension, to account for edge distances
when bond failure occurs at the grout/concrete interface.

Yc,e = modification factor, for strength in tension, to account for edge distances
when concrete cone breakout failure occurs.















APPENDIX B
TENSILE LOAD VS. DISPLACEMENT GRAPHS FOR BASELINE AND HOLE
DRILLING TECHNIQUE TEST SERIES

This appendix contains the results from testing of single anchors installed away

from an edge. Table B-l lists the details about each test performed including the

installation number, the effect being tested, the anchor number in the given test series, the

average concrete compressive stress at the time of testing, the failure mode, the tensile

strength of the anchor, and the bond stress of the anchor. Figures B-l through B-5 depict

the axial tensile load versus the vertical displacement for the various tests performed.

The title of each graph within the figures denotes information about the test being

performed. The first two letters in the title specify the type of hole drilled. Core-drilled

holes are represented by CD, and hammer-drilled holes are represented by HD. The first

number identifies the test series of the hole type. The second number identifies the

individual anchor in the series.










Table B-1 Individual baseline and hole drilling technique anchor test results

Installation # Tested Anchor fc at test Failure te kips (kN) o. psi (MPa)
Effect in Series psi (MPa) Modet p
1 Baseline 1 6600(45.5) g/c 27.6 (123) 1170 (8.07)
1 Baseline 2 6600(45.5) g/c 30.2 (134) 1280 (8.84)
1 Baseline 3 6680(46.1) g/c 28.67 (127) 1220 (8.39)
1 Baseline 4 6680(46.1) g/c 29.2 (130) 1240 (8.54)
1 Baseline 5 6680(46.1) g/c 31.1 (138) 1320 (9.09)
1 Hammer 1 6600(45.5) g/c 30.0 (134) 1280 (8.79)
1 Hammer 2 6600(45.5) steel 26.1(116) NA
1 Hammer 3 6680 (46.1) g/c 30.6 (136) 1300 (8.94)
1 Hammer 4 6680(46.1) steel 24.4 (109) NA
1 Hammer 5 6680(46.1) steel 24.1(107) NA
2 Baseline 1 7200 (49.6) g/c 35.8 (159) 1520 (10.5)
2 Baseline 2 7200 (49.6) g/c 36.1 (160) 1530 (10.6)
2 Baseline 3 7200 (49.6) g/c 33.5 (149) 1420 (9.80)
2 Hammer 1 7200 (49.6) g/c 38.9 (173) 1650 (11.4)
2 Hammer 2 7200 (49.6) g/c 20.0 (89.2) 851(5.86)
2 Hammer 3 7200 (49.6) g/c 28.0 (125) 1190 (8.19)
3 Baseline 1 7330 (50.5) g/c 41.7 (186) 1770 (12.2)
3 Baseline 2 7330 (50.5) g/c 41.3 (184) 1750 (12.1)
3 Baseline 3 7330 (50.5) g/c 34.9 (155) 1480 (10.2)














CD 1-1
45

40

35

2 30 27.5697 -

1 25
10
S20- -

a 15


5
0


0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in



A)

CD 1-3
45

40

35
.S 30 28.65726

25
20


15 -

10 / --
-5






5 '----'----'--------'-

0.00 0.05 0.10 0.15 0.20 0.25

Axial Displacement, in



C)

CD 1-5
45
40

35
31.07245
30 -

S25 -

w 20

S15

10
5

0
0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


CD 1-2


0 '
0.00 0.05


30.18909


0.10 0.15
Axial Displacement, in


0.20 0.25


CD 1-4


29.18651


0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in



D)
CD 1-1, CD 1-2, CD 1-3, CD 1-4, CD 1-5


0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in




F)


Figure B-l Graphs of test results of first installation of core-drilled anchors A) First test

in series; B) Second test in series; C) Third test in series; D) Fourth test in series; E) Fifth

test in series; F) Comparison of all test in series












CD 2-1
45
40
35.76472
35
.30
S25
0








-J3
L 20




10


0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


A)

CD 2-3
45 -
40
35 33.49185 -
.30
S25


S5
is




0
0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


45
40




20
2- -

15
10
5
0
0.00 0.05






45


CD 2-2


0.10 0.15
Axial Displacement, in


B)
CD 2-1, CD 2-2, CD 2-3


0.20 0.25


40
35


S25


a 15
2O

10


0
0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


Figure B-2 Graphs of test results of second installation of core-drilled anchors A) First
test in series; B) Second test in series; C) Third test in series; D) Comparison of all test in
series








68



CD 3-1 CD 3-2
45 99 45 -
41.74099 41.30884
40 40

35 35

.E 30 30


S20 a' 20

15 15


5 5
10 10 -


0 0
0.00 0.05 0.10 0.15 0.20 0.25 0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in Axial Displacement, in


A) B)

CD 3-3 CD 3-1, CD 3-2, CD 3-3

40 40

35 35
305 34.9 3 -3 -5 -

S30 30

S25 25
o 0
-1 -J
2 20 2 20


10 10

5 5

0 0
0.00 0.05 0.10 0.15 0.20 0.25 0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in Axial Displacement, in


C) D)


Figure B-3 Graphs of test results of third installation of core-drilled anchors A) First test
in series; B) Second test in series; C) Third test in series; D) Comparison of all test in
series













HD 1-1
45
40
35
S3 30.04109
. 30 - -

25
10
-j
Lu 20

c 15
10

5
0
0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


45
40
35
30
25
20
15
10
5
0
0.0


HD 1-2 Steel Broke






26.07954


10


HD 1-3


0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


HD 1-4 Steel Broke


30.5521


24.4132


0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


HD 1-5 Steel Broke


0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


HD 1-1, HD 1-2, HD 1-3, HD 1-4, HD 1-5


24.04969


0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


0.00 0.05 0.10 0.15
Axial Displacement, in


Figure B-4 Graphs of test results of first installation of hammer-drilled anchors A) First
test in series; B) Second test in series; C) Third test in series; D) Fourth test in series;

E) Fifth test in series; F) Comparison of all test in series


35

. 30

S25
0
2 20

15
10


0
0.


00


45
40
35
" 30

" 25
2 20
S 15
10
5
0
0.0


0


0.20 0.25


- -
- -
/I --- _7














HD 2-1
45

40 38.8617

35

2- 30

S25
0
i 20





5
a 15




0
0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


A)

HD 2-3


27.98995


0.05 0.10 0.15
Axial Displacement, in


45

40

35

-30

S25
0
w 20

a 15

10

5

0
0.0


45

40

35

. 30

S25
0
P 20

15

10

5

0
0.00


0.20 0.25


HD 2-2









20.04401


10


0.05


0.10 0.15
Axial Displacement, in



B)

HD 2-1, HD 2-2, HD 2-3


0.20 0.25


0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


Figure B-5 Graphs of test results of second installation of hammer-drilled anchors

A) First test in series; B) Second test in series; C) Third test in series; D) Comparison of

all test in series


45

40

35
to
.- 30

S25
0
. 20

S 15

10
15



0
0.00
0.00















APPENDIX C
TENSILE LOAD VS. DISPLACEMENT GRAPHS FOR EDGE DISTANCE TEST
SERIES

This appendix contains the results from testing of single anchors installed near

one edge. Table C-1 lists the details about each test performed including the installation

number, the effect being tested, the anchor number in the given test series, the average

concrete compressive stress at the time of testing, the failure mode, the tensile strength of

the anchor, and the bond stress of the anchor. Figures C-l through C-3 depict the axial

tensile load versus the vertical displacement for the various tests performed. The title of

each graph within the figures denotes information about the test being performed. The

first letter in the title specifies that an edge test is being performed. The first number

identifies the edge distance of the test series. The second number identifies the individual

anchor in the series.










Table C-l Individual edge distance anchor test results


Insta n # Tested Anchor fc at test Failure N kips (kN) cot si (MPa)
Effect in Series psi (MPa) Modet p
2 Edge 7.5 1 6460(44.5) g/c 29.7 (132) 1260 (8.70)
2 Edge 7.5 2 6460(44.5) g/c 31.95 (142.14) 1360 (9.35)
2 Edge 7.5 3 6460(44.5) g/c 36.5 (162) 1550 (10.7)
2 Edge 7.5 4 6460(44.5) g/c 33.1 (147) 1400 (9.67)
2 Edge 7.5 5 6460 (44.5) g/c 28.3 (126) 1200 (8.29)
3 Edge 4.5 1 7600 (52.4) g/c 32.2 (143) 1370 (9.42)
3 Edge 4.5 2 7600 (52.4) g/c 28.2 (126) 1200 (8.26)
3 Edge 4.5 3 7600 (52.4) g/c 30.1 (134) 1280 (8.80)
3 Edge 4.5 4 7600(52.4) g/c 26.7(119) 1130(7.81)
3 Edge 4.5 5 7600 (52.4) g/c 26.3 (117) 1110 (7.68)
3 Edge 6.0 1 7330 (50.5) g/c 36.2 (161) 1540 (10.6)
3 Edge 6.0 2 7330 (50.5) g/c 30.9 (137) 1310 (9.04)
3 Edge 6.0 3 7330 (50.5) g/c 32.6 (145) 1390 (9.55)
3 Edge 6.0 4 7330 (50.5) g/c 32.3 (144) 1370 (9.45)
3 Edge 6.0 5 7330 (50.5) g/c 30.4 (135) 1290 (8.90)














E 4.5-1


32.1853


35

.2 30

S25
0
. 20

15

10

5

0
0.00


0.20 0.25


35

.. 30 28.22571

P 25
20



51



0
0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


A)

E 4.5-3


B)

E 4.5-4


30.08161


26.69852


0.05 0.10 0.15
Axial Displacement, in


0.20 0.25


E 4.5-5


0.00 0.05 0.10 0.15 0.20
Axial Displacement, in


D)

E 4.5-1, E 4.5-2, E 4.5-3, E 4.5-4, E 4.5-5


0.05 0.10 0.15
Axial Displacement, in


020 n 925


40

35

.- 30

4 25

20



10

5
5 -

0
0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


Figure C-l Graphs of test results of core-drilled anchors installed 4.5 inches away from

one edge A) First test in series; B) Second test in series; C) Third test in series; D) Fourth

test in series; E) Fifth test in series; F) Comparison of all test in series


0.05 0.10 0.15
Axial Displacement, in


35
to
.- 30

S25
0


15

10

5

0
0.00


0.25


40

35

30

25

20

15

10

5

0
0 0


E 4.5-2














E 6.0-1


36.23166


45

40

35

.- 30

S25

.u 20

a 15
10



0-
0.00


0.20 0.25


45

40

35

. 30

S25
0
S20

15


5
10



0
0.00


0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


E 6.0-3


E 6.0-4


32.29447


0.05 0.10 0.15
Axial Displacement, in


0.20 0.25


E 6.0-5


0.05 0.10 0.15
Axial Displacement, in


0.20 0.25


0.00 0.05 0.10 0.15 0.20
Axial Displacement, in


DE

E 6.0-1, E 6.0-2, E 6.0-3, E 6.0-4, E 6.0-5


0.25


0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


Figure C-2 Graphs of test results of core-drilled anchors installed 6.0 inches away from

one edge A) First test in series; B) Second test in series; C) Third test in series; D) Fourth

test in series; E) Fifth test in series; F) Comparison of all test in series


0.05 0.10 0.15
Axial Displacement, in


45

40

35

- 30

25
0


15


5
10

0
0.00


45

40

35

. 30

25
0
a 20

15

10


0
0.00


E 6.0-2














E 7.5-1


35
S30 29.73766
25 -

2 15 - - -

S20- -

S, 15 -

10

5

0
0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in



A)

E 7.5-3


40

35

- 30

25
S20



-J
.20
S15




10

0.00


0.05 0.10 0.15
Axial Displacement, in


0.20 0.25


0 0.
0.00 0.05


31.95368


0.10 0.15
Axial Displacement, in


0.20 0.25


E 7.5-4


33.05069


0.00 0.05 0.10 0.15 0.20
Axial Displacement, in


C
E 7.5-5
45


0.05 0.10 0.15
Axial Displacement, in



E)


020 n 925


D)
E 7.5-1, E 7.5-2, E 7.5-3, E 7.5-4, E 7.5-5


40

35

.2 3 0 - -

S25
0
s 20

15

10



0
0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


F)


Figure C-3 Graphs of test results of core-drilled anchors installed 7.5 inches away from

one edge A) First test in series; B) Second test in series; C) Third test in series; D) Fourth

test in series; E) Fifth test in series; F) Comparison of all test in series


0.25


40

35

- 30

S25
20
'1
' 15

10

5

0
o 0o


E 7.5-2















APPENDIX D
TENSILE LOAD VS. DISPLACEMENT GRAPHS FOR GROUP TEST SERIES

This appendix contains the results from testing of anchor groups. Table D-1 lists

the details about each test performed including the installation number, the effect being

tested, the group number in the given test series, the average concrete compressive stress

at the time of testing, the failure mode, the anchor number in the given test series, the

tensile strengths of the individual anchors as well as the anchor group, and the bond

stresses of the individual anchors and the anchor group. Figures D-1 through D-6 depict

the axial tensile load versus the vertical displacement for the various tests performed.

The title of each graph within the figures denotes information about the test being

performed. The first letter in the title specifies that a group test is being conducted. The

first number identifies the anchor spacing of the test series. The second number identifies

the group in a series. The remaining letters specify the load measuring instrument being

used. The load washer on each anchor is represented by LW, and the overall load cell for

the anchor group is represented by OLC. The third number identifies the individual

anchor on which data is being measured.










Table D-1 Individual group anchor test results


Tested Group in fc at test Failure
Installation # Tested Group in f attest Failue Anchor Nte,, kips (kN) To,test psi (MPa)
Effect Series psi (MPa) Mode
1 Error NA
2 13.7 (61.1) NA
7670
1 G 5.0 1 (52 cone 3 15.2 (67.5) NA
4 13.2 (58.5) NA
All 63.4 (282) NA
1 Error NA
2 13.8 (61.2) NA
7670
1 G 5.0 2 (52.9) cone 3 16.1(71.8) NA
4 16.2(72.1) NA
All 66.9 (298) NA
1 Error NA
2 16.7 (74.1) NA
7670
1 G 5.0 3 (52.9) cone 3 13.67 (60.8) NA
4 15.0 (66.6) NA
All 62.0 (276) NA
1 Error Error
2 27.5 (122) 1170 (8.05)
7330
3 G 9.0 1 (50.5) g/c 3 28.6 (127) 1210 (8.37)
4 25.3 (112) 1070(7.39)
All 105 (465) 1110 (7.65)
1 Error Error
2 22.2 (98.7) 942 (6.49)
7330
3 G 9.0 2 (50.5) g/c 3 24.3 (108) 1030 (7.10)
4 32.7 (145) 1390 (9.57)
All 106 (469) 1120 (7.72)
1 Error Error
2 21.1(93.7) 894(6.16)
7330
3 G 9.0 3 (50.5) g/c 3 23.4 (104) 991 (6.83)
4 25.5 (114) 1080 (7.47)
All 100 (446) 1070 (7.34)














G 5-1 LW 1- Instrument Malfunction


35

30

25

20

15

10

5

0
0.0


0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


13.72662


0


G 5-1 LW 3


15.17856






0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


0.05 0.10 0.15
Axial Displacement, in


0.20 0.25


G 5-1 LW 4


13.16129- -


0.00 0.05


0.10 0.15
Axial Displacement, in


0.20 0.25


D)
G 5-1 OLC


G 5-1 LW 1-4


40

35

" 30

S25
o0
c20
i 15




0
0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


63.35037


0.00 0.05 0.10 0.15
Axial Displacement, in


Figure D-1 Graphs of results of first core-drilled anchor group installed with anchor

spacing of 5.0 inches A) Load on first anchor; B) Load on second anchor; C) Load on

third anchor; D) Load on fourth anchor; E) Comparison of all anchor loads in test;

F) Load on entire anchor group


0.20 0.25


G 5-1 LW 2














G 5-2 LW 1- Instrument Malfunction


35

. 30
.=

" 25

. 20

S15

10

5

0
0.00


35

30

25

20

15

10

5

0
0.0


0.20 0.25


13.75545 -


0


G 5-2 LW 3


E. 30

" 25

. 20
u' 16.13572
1 15
5
10 -

5 -

0
0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


0.10 0.15
Axial Displacement, in


0.20 0.25


G 5-2 LW 4


E 30

S25
20
.u 20
16.19654
1 15

10



0
0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


C 1

G 5-2 LW 1-4


0.05 0.10 0.15
Axial Displacement, in


D)

G 5-2 OLC
66.92794


0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


0.20 0.25


Figure D-2 Graphs of results of second core-drilled anchor group installed with anchor

spacing of 5.0 inches A) Load on first anchor; B) Load on second anchor; C) Load on

third anchor; D) Load on fourth anchor; E) Comparison of all anchor loads in test;

F) Load on entire anchor group


0.05 0.10 0.15
Axial Displacement, in


45

40

35

- 30

25
20
o 20

15

10

5

0
0.00


G 5-2 LW 2














G 5-3 LW 1- Instrument Malfunction


35

. 30

" 25

. 20

S15

10

5

0
0.00


0.05 0.10 0.15
Axial Displacement, in


35

.E30

S25
0
S20

S15

10

5

0
0.0


0.20 0.25


16.65167


10


G 5-3 LW 3


0.05 0.10 0.15
Axial Displacement, in


G 5-3 LW 4


14.96143


13.65523


0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


C)

G 5-3 LW 1-4
45


0.05 0.10 0.15
Axial Displacement, in


D)
G 5-3 OLC


0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


Figure D-3 Graphs of results of third core-drilled anchor group installed with anchor

spacing of 5.0 inches A) Load on first anchor; B) Load on second anchor; C) Load on

third anchor; D) Load on fourth anchor; E) Comparison of all anchor loads in test;

F) Load on entire anchor group


35

S30

" 25
-,
2 20

0 15

10

5

0


0.20 0.25


G 5-3 LW 2














G 9-1 LW 2


G 9-1 LW 1- Instrument Malfunction


35

- 30

S25
-j
S20

15

10

5

0 -
-0.10


35

S30 27.49868 -

S25

S20 /

15


10



-0.10 -0.05 0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


G 9-1 LW 3


G 9-1 LW 4


28.59958


-0.05 0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


35

L 30

r 25
0
2 20

S 15

10

5

0
-0.10


25.26089











-0.05 0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


G 9-1 LW 1-4
45

40

35

30

25 -

20

15

10

5

0
-0.10 -0.05 0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


G 9-1 OLC
110 104.59455
100
90
80
70
60 -
50
40
30
20 -
10


0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


Figure D-4 Graphs of results of first core-drilled anchor group installed with anchor

spacing of 9.0 inches A) Load on first anchor; B) Load on second anchor; C) Load on

third anchor; D) Load on fourth anchor; E) Comparison of all anchor loads in test;

F) Load on entire anchor group


-0.05 0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


45

40

35

30

25

20

15

10

5

0
-0.10















G 9-2 LW 1- Instrument Malfunction


35

S30
.C
" 25
20
"i20

S 15
I-
10

5

0
0.00


0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


G 9-2 LW 3
45

40

35

- 30

0
25 -24.25150

S20 /- -- -' -- --
a 20

c 15

10 -



0
0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


22.19361
- ------,


- :-- -- -- -- -- --


0.05 0.10 0.15
Axial Displacement, in


G 9-2 LW 4


32.70422


0.00 0.05 0.10 0.15
Axial Displacement, in


G 9-2 LW 1-4


0.05 0.10 0.15
Axial Displacement, in


0.20 0.25


D)

G 9-2 OLC
110 105.50309
100
90
80
70
60
50
40
30
20
10
0
0 J'----------------

0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


Figure D-5 Graphs of results of second core-drilled anchor group installed with anchor

spacing of 9.0 inches A) Load on first anchor; B) Load on second anchor; C) Load on

third anchor; D) Load on fourth anchor; E) Comparison of all anchor loads in test;

F) Load on entire anchor group


0.20 0.25


0.20 0.25


45

40

35

.- 30

i 25
20
S 20

S 15

10

5

0
0.00


G 9-2 LW 2














G 9-3 LW 1- Instrument Malfunction


35

30

25

20

15

10

5

0
0.0


35

S30

" 25

2 20

, 15

10

5

0
0.00


21.06149
-/ / -


0


G 9-3 LW 3


0.05 0.10 0.15
Axial Displacement, in


G 9-3 LW 4


25.52293


23.34821'




-- -


0.05 0.10 0.15 0.20
Axial Displacement, in


0.25


0.00 0.05 0.10 0.15
Axial Displacement, in


G 9-3 LW 1-4


0.05 0.10 0.15
Axial Displacement, in


0.20 0.25


G 9-3 OLC
110
100.31756
100 -
90
80
70
60
50
40
30
20
10
0
0.00 0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


Figure D-6 Graphs of results of third core-drilled anchor group installed with anchor

spacing of 9.0 inches A) Load on first anchor; B) Load on second anchor; C) Load on

third anchor; D) Load on fourth anchor; E) Comparison of all anchor loads in test;

F) Load on entire anchor group


0.05 0.10 0.15 0.20 0.25
Axial Displacement, in


0.20 0.25


35

. 30

" 25

2 20

, 15

10

5

0
0.


00


0.20 0.25


45

40

35

- 30

, 25
20
o 20

15

10



0
0.00


G 9-3 LW 2
















APPENDIX E
REPRESENTATIVE PHOTOGRAPHS OF ANCHOR SPECIMENS FROM TESTING


Figure E-1 Typical grout/concrete bond failure of single core-drilled anchor with grout
plug


Figure E-2 Typical grout/concrete bond failure of single anchor with secondary shallow
concrete cone






























Figure E-3 Grout/concrete bond failure of single core-drilled anchor with secondary
shallow cone removed and grout plug exposed


Figure E-4 Typical grout/concrete bond failure of single hammer-drilled anchor with
grout plug

































Figure E-5 Typical grout/concrete bond failure of single hammer-drilled anchor with
secondary shallow concrete cone and grout plug








.... ... .
















Figure E-6 Typical grout/concrete bond failure of single core-drilled anchor installed 4.5
inches from one edge with grout plug and diagonal cracking of surrounding concrete





























Figure E-7 Typical grout/concrete bond failure of single core-drilled anchor installed 6.0
inches from one edge with grout plug


Figure E-8 Typical grout/concrete bond failure of single core-drilled anchor installed 7.5
inches from one edge with grout plug





































Figure E-9 Typical surface view of cone failure of quadruple fastener anchor group with
anchor spacing of 5 inches


H 7 H

-. -.


Figure E-10 Typical dissection view of cone failure of quadruple fastener anchor group
with anchor spacing of 5 inches





























Figure E-11 Typical grout/concrete failure of quadruple fastener anchor group with
anchor spacing of 9 inches