<%BANNER%>

Windborne Debris Missile Impacts on Window Glazing and Shutter Systems

Permanent Link: http://ufdc.ufl.edu/UFE0024129/00001

Material Information

Title: Windborne Debris Missile Impacts on Window Glazing and Shutter Systems
Physical Description: 1 online resource (99 p.)
Language: english
Creator: Shah, Nirav
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2009

Subjects

Subjects / Keywords: glazing, roof, shingle, shutter, windborne
Civil and Coastal Engineering -- Dissertations, Academic -- UF
Genre: Civil Engineering thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Windborne debris is a significant cause of damage to the building envelope in major hurricanes. The building envelope consists of the roof, doors, windows and cladding components of a building. The failure of the building envelope results in internal pressurization of the structure, which effectively increases the wind loads on cladding and components of building envelope and exposes the building contents to wind-driven rain. In particular, post-hurricane investigations reports have shown that windborne debris is a significant hazard to glass during wind storms. This research aims to investigate the effects of windborne asphalt roof shingles on window glazing. Impact tests were conducted on 3.18 mm (1/8?) annealed and 4.76 mm (3/16?) annealed glass. New and old roof shingle tabs, both full weight and half weight, were considered. Two types of flight modes were considered, autorotation and tumbling. An analysis of variance (ANOVA) was performed on the experimental data to correlate glass thickness, missile weight and momentum required to break the glass. Roofing tile or tile fragments have been also observed to damage window shutters and the glazing behind them. In this research, a second series of tests were performed to investigate the performance of window shutter systems when subjected to the impact of roofing tiles and a standard 2x4 missile. Impact tests were performed at two different impact speeds, 20.12 m/s (45 mph) and 15.2 m/s (34 mph), and with two types of installation methods, direct mount method and tracking method. Deflections due to impact of the tile missile and 2x4 lumber were recorded and compared.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Nirav Shah.
Thesis: Thesis (M.S.)--University of Florida, 2009.
Local: Adviser: Masters, Forrest.

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2009
System ID: UFE0024129:00001

Permanent Link: http://ufdc.ufl.edu/UFE0024129/00001

Material Information

Title: Windborne Debris Missile Impacts on Window Glazing and Shutter Systems
Physical Description: 1 online resource (99 p.)
Language: english
Creator: Shah, Nirav
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2009

Subjects

Subjects / Keywords: glazing, roof, shingle, shutter, windborne
Civil and Coastal Engineering -- Dissertations, Academic -- UF
Genre: Civil Engineering thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Windborne debris is a significant cause of damage to the building envelope in major hurricanes. The building envelope consists of the roof, doors, windows and cladding components of a building. The failure of the building envelope results in internal pressurization of the structure, which effectively increases the wind loads on cladding and components of building envelope and exposes the building contents to wind-driven rain. In particular, post-hurricane investigations reports have shown that windborne debris is a significant hazard to glass during wind storms. This research aims to investigate the effects of windborne asphalt roof shingles on window glazing. Impact tests were conducted on 3.18 mm (1/8?) annealed and 4.76 mm (3/16?) annealed glass. New and old roof shingle tabs, both full weight and half weight, were considered. Two types of flight modes were considered, autorotation and tumbling. An analysis of variance (ANOVA) was performed on the experimental data to correlate glass thickness, missile weight and momentum required to break the glass. Roofing tile or tile fragments have been also observed to damage window shutters and the glazing behind them. In this research, a second series of tests were performed to investigate the performance of window shutter systems when subjected to the impact of roofing tiles and a standard 2x4 missile. Impact tests were performed at two different impact speeds, 20.12 m/s (45 mph) and 15.2 m/s (34 mph), and with two types of installation methods, direct mount method and tracking method. Deflections due to impact of the tile missile and 2x4 lumber were recorded and compared.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Nirav Shah.
Thesis: Thesis (M.S.)--University of Florida, 2009.
Local: Adviser: Masters, Forrest.

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2009
System ID: UFE0024129:00001


This item has the following downloads:


Full Text

PAGE 1

1 WINDBORNE DEBRIS MISSILE IMPACTS ON WINDOW GLAZING AND SHUTTER SYSTEMS By NIRAV SHAH A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLOR IDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2009

PAGE 2

2 2009 Nirav Shah

PAGE 3

3 To my family; Mom Hema Shah, Dad Sunil Shah, and Sister Namrata Shah For your support and encouragement in all my academic endeavors

PAGE 4

4 ACKNOWLEDGMENT I express m y most sincere gr atitude to my advisor and chairman of the supervisory committee, Dr. Forrest Masters, for his constant guidance, enc ouragement, and support. I also thank other committee members including Dr. Kur tis Gurley and Dr. David Prevatt for their assistance. I thank Dr. Jim Austin and Chuck Broward. I also appr eciate friendly and helpful lab mates: George Fernandez and Jimmy Jesteadt. I am extremely grateful to my parents, Sunil Shah and Hema Shah, for their love and encouragement during my entire life. I thank my grandparents, my sister, and Amin Family for their support.

PAGE 5

5 TABLE OF CONTENTS page ACKNOWLEDGMENT..................................................................................................................4 LIST OF TABLES................................................................................................................. ..........8 LIST OF FIGURES.......................................................................................................................10 ABSTRACT...................................................................................................................................12 CHAP TER 1 INTRODUCTION..................................................................................................................14 1.1 Extreme Wind Effects on Low-Rise Buildings................................................................ 15 1.2 Damage Due to Wind Borne Debris................................................................................. 16 1.3 Thesis Summary...............................................................................................................18 2 BACKGROUND.................................................................................................................... 22 2.1 Common Windborne Debris Types.................................................................................. 22 2.2 Windborne Missile Imp act Test Standards ....................................................................... 23 2.2.1 History of Windborne Mi ssile Test Standards ....................................................... 23 2.2.2 American Society of Tes ting and Materials (ASTM) ............................................ 24 2.2.2.1 The ASTM E 1886-02 (Standard test method for performance of exterior windows, curtain walls, doo rs and storm shutters im pacted by missile(s) and exposed cyclic pressure differentials)........................................... 24 2.2.2.2 The ASTM E 1996-03 (Standard Test Method for performance of exterior windows, curtain walls, doo rs, and storm shutters impacted by windborne debris in a hurricane) .......................................................................... 25 2.2.3 Florida Building Code (FBC) (TAS 201: Impact Test Procedure) ........................ 26 2.2.4 American Architectural Manufacturers Association (AAMA).............................. 27 2.2.4.1 The AAMA 506 (Voluntary specificati ons for hurricane im pact and cycle testing of fenestration product)................................................................... 27 2.2.4.2 The AAMA/WDMA/CSA 101/I.S.2/A 440 (Standard specification for windows, doors and unit skylights) C lause 5.3.10 (Impact performance)........... 27 2.2.5 American Society of Ci vil Engineers (ASCE 7-05) ............................................... 27 2.2.6 Standard Building Code (SSTD 12-94) (S BCCI Test Standard for Determining Impact Resistan ce from Windborne Debris).......................................... 28 2.2.7 International Building Code (IBC) and International Residential Code (IRC) ......29 2.2.8 The ICC/NSSA Standard on the Design and Construction of Stor m Shelters (Draft)..........................................................................................................................29 2.3 Previous Research.......................................................................................................... ...30 2.3.1 Texas Tech University............................................................................................ 30 2.3.2 The NAHB Research Center.................................................................................. 31

PAGE 6

6 2.4 Windborne Debris Damage Models................................................................................. 32 2.5 Summary...........................................................................................................................33 3 IMPACT OF SHINGLE MISSILES ON GLAZING.............................................................38 3.1 Experimental Configuration.............................................................................................38 3.1.1 Shingle Launcher....................................................................................................38 3.1.2 Specimen Box and Glazing Support Frame........................................................... 39 3.1.3 A High-Speed Camera............................................................................................39 3.2 Test Materials...................................................................................................................39 3.3 Experimental Procedure.................................................................................................... 40 3.3.1 Installation of Test Specimen.................................................................................40 3.3.2 Preparation of Shingle Missile...............................................................................40 3.3.3 Missile Impact on Glazing...................................................................................... 40 3.3.4 Interpretation..........................................................................................................41 3.4 Results...............................................................................................................................42 3.5 Discussion of Results........................................................................................................43 4 IMPACT OF ROOFING TILES AND 2X 4 MI SSILES ON WINDOW SHUTTERS.......... 54 4.1 Experimental Configuration.............................................................................................54 4.1.1 Reaction Frame and Shutter Mounts...................................................................... 54 4.1.2 Tile Projectile Launcher......................................................................................... 55 4.1.3 The 2x4 Projectile Launcher.................................................................................. 56 4.1.4 A High-Speed Camera............................................................................................56 4.2 Test Materials...................................................................................................................57 4.3 Experimental Procedure.................................................................................................... 57 4.3.1 Installation of Test Specimen Assembly................................................................ 57 4.3.2 Preparation of Missiles........................................................................................... 57 4.3.3 Missile Impact on Hurricane Shutters.................................................................... 58 4.3.4 Data Collection....................................................................................................... 58 4.4 Results...............................................................................................................................58 4.5 Discussion of Results........................................................................................................59 5 CONCLUSIONS AND RECOMME NDATIONS................................................................. 75 5.1 Conclusions.......................................................................................................................75 5.1.1 Impact of Shingle Missiles on Glazing.................................................................. 75 5.1.2 Impact of Roofing Tiles and 2x4 Missiles on W indow Shutters............................ 76 5.2 Recommendations for Future Research............................................................................ 76 APPENDIX A SAMPLE DATA WORKSHEET FO R SHI NGLE MISSILE IMPACT............................... 78 B SHINGLE VELOCITY CALIBRATI ON AND CO-EFFICI ENT OF GRIP........................79 C GLASS BREAKAGE VELOCITY........................................................................................ 86

PAGE 7

7 D SHINGLE SIZE REDUCTION.............................................................................................. 87 E SAMPLE DATA WORKSHEET FOR SHUTTER TESTING .............................................89 F MEASUREMENT OF MISSILE VELOCITY...................................................................... 90 G ONE WAY ANALYSIS OF VARIANCE (ANOVA)........................................................... 93 REFERENCES..............................................................................................................................95 BIOGRAPHICAL SKETCH.........................................................................................................99

PAGE 8

8 LIST OF TABLES Table page 2-1 Windborne missiles and classification (FEMA 2000)...................................................... 352-2 Cyclic static air pre ssure loading (ASTM E1986-02).......................................................352-3 Wind zone classification (ASTM E1996-03)................................................................... 352-4 Applicable missile (ASTM E1996-03)............................................................................. 352-5 Missile impact test for appropriate level of building prot ection (ASTM E1996-03)....... 363-1 Test specimen matrix........................................................................................................ 443-2 Threshold momentum fo r various glass specimens.......................................................... 453-3 Threshold kinetic energy for various glass specimens.....................................................463-4 ANOVA test between 0.61 m (2 ft) x 0.61 m (2 ft) x 3.18 mm (1/8 in) glass and 0.61 m (2 ft) x 0.61 m (2 ft) x 4.76 mm (3/16 in ) glass using full weight new shingle.............463-5 ANOVA test between 0.61 m (2 ft) x 0.61 m (2 ft) x 3.18 mm (1/8 in) glass and 0.61 m (2 ft) x 1.22 m (4 ft) x 3.18 mm (1/8 in ) glass using full weight new shingle............... 473-6 ANOVA test between full weight new shingle and half weight new shingle for 0.61 m (2 ft) x 0.61 m (2 ft) x 3.18 mm (1/8 in) glass............................................................... 473-7 ANOVA test between full weight new shi ngle and full weight old roof shingle for 0.61 m (2 ft) x 0.61 m (2 ft) x 3.18 mm (1/8 in) glass....................................................... 473-8 ANOVA test between half weight new shi ngle and half weight old roof shingle for 0.61 m (2 ft) x 0.61 m (2 ft ) 3.18 mm (1/8 in) glass.......................................................... 483-9 ANOVA test between full weight old roof shingle and half wei ght old roof shingle for 0.61 m (2 ft) x 0.61 m (2 ft) 3.18 mm (1/8 in) glass.................................................... 483-10 ANOVA test between Autorotation mode and Tumbling mode of flight for 0.61 m (2 ft) x 0.61 m (2 ft) 3.18 mm (1/8 in) glass impact by new full weight shingle................... 483-11 Results summary of mean threshold velocity, momentum, and kinetic energy for glazing testing................................................................................................................ ....494-1 Missile impact test results for round 1 te sting at approximately 20.12 m/s (45 mph)....... 604-2 Missile impact test results for round 2 testing at approximate ly 15.2 m/s (34 mph)......... 60

PAGE 9

9 4-3 Momentum and kinetic energy for various test specim ens at approximately 20.12 m/s (45 mph).............................................................................................................................614-4 Momentum and kinetic energy for various test specimens at approximately 15.2 m/s (34 mph).............................................................................................................................614-5 Results summary of mean threshold velocity, momentum, kinetic energy and deflection for window shutters testing...............................................................................614-6 ANOVA test between tile missile and 2x4 missile using an H-box assembly at 15.2 m/s (34 mph)................................................................................................................... ...624-7 ANOVA test between tile missile and 2x4 missi le using the direct mount assembly at 15.2 m/s (34 mph).............................................................................................................. 62A-1 Sample data worksheet for glazing tests............................................................................ 78C-1 Glass breakage velocity.................................................................................................... .86E-1 Sample data worksheet for shutter tests............................................................................. 89F-1 Cannon pressure Vs tile speed........................................................................................... 91

PAGE 10

10 LIST OF FIGURES Figure page 1-1 Wind flow around building............................................................................................... 19 1-2 Windward wall opening caused increase in internal pressure (side view )....................... 20 1-3 Window shutter damage due to Spanish tile. (Reinhold 2005) ........................................ 20 1-4 Percentage of homes wi th at least one window damaged as a function of neighborhood roof cover type and window protection. (Gurley 2006)............................. 21 2-1 Location of large missile impacts on three test specim ens (ASTM E1996-03)............... 37 2-2 Location of small missile impacts on three test specim ens (ASTM E1996-03)............... 37 3-1 Testing facility. ............................................................................................................. ....50 3-2 Shingle missile launcher.................................................................................................. .51 3-3 Common glass breakage patterns......................................................................................52 4-1 Reaction frame..................................................................................................................63 4-2 Tile missile launcher..................................................................................................... ....63 4-3 Labview program view for tile missile launcher.............................................................. 65 4-4 Board marked with reference lines spaced at 2.54 cm (1 in)............................................ 65 4-5 Types of installation at header and s ill level..................................................................... 66 4-6 Tile missile impact test for H-box assem bly, center shot (Test A-1)............................... 66 4-7 Tile missile impact test for H-box assem bly, seam shot (Test A-2)................................. 67 4-8 2X4 lumber missile impact test fo r H-box assembly, seam shot (Test B-1).................... 67 4-9 2X4 lumber missile impact test fo r H-box assembly, center shot (Test B-2) ................... 68 4-10 2X4 lumber missile impact test fo r H-box assembly, seam shot (Test B-3).................... 68 4-11 Tile missile impact test for direct mount assem bly, center shot (Test C-1).....................69 4-12 Tile missile impact test for direct mount assem bly, seam shot (Test C-2)....................... 69 4-13 2X4 lumber missile impact test for direct m ount assembly, seam shot (Test D-1).......... 70

PAGE 11

11 4-14 2X4 lumber missile impact test for direct m ount assembly, center shot (Test D-2)........ 70 4-15 Tile missile impact test for H-box assem bly, center shot (Test E-1)................................ 71 4-16 Tile missile impact test for H-box assem bly, seam shot (Test E-2)................................. 71 4-17 2X4 lumber missile impact test fo r H-box assembly, center shot (Test F-1) ...................72 4-18 2X4 lumber missile impact test fo r H-box assembly, seam shot (Test F-2)..................... 72 4-19 Tile missile impact test for direct mount assem bly, seam shot (Test G-1)....................... 73 4-20 Tile missile impact test for direct mount assem bly, center shot (Test G-2)..................... 73 4-21 2X4 lumber missile impact test for direct m ount assembly, center shot (Test H-1)........ 74 4-22 2X4 lumber missile impact test for direct m ount assembly, seam shot (Test H-2).......... 74 B-1 Wheel speed plot corresponding to motor RPM............................................................... 81 B-2 Calibration of full weight ne w shingle velocity at 600 RPM.. ......................................... 82 B-3 Corrected distance travelle d by shingle m issile for 600 RPM..........................................84 B-4 Corrected shingle speed pl ot corresponding to motor RPM ............................................. 85 D-1 Three-tab shingle..............................................................................................................87 D-2 Shingle size reduction.......................................................................................................88 F-1 Corrected distance travelled by tile m issile...................................................................... 92

PAGE 12

12 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 Science WINDBORNE DEBRIS MISSILE IMPACTS ON WINDOW GLAZING AND SHUTTER SYSTEMS By Nirav Shah May 2009 Chair: Forrest Masters Major: Civil Engineering Windborne debris is a significant cause of damage to the building envelope in major hurricanes. The building envelope consists of the roof, doors, windows and cladding components of a building. The failure of the building envelo pe results in internal pressurization of the structure, which effectively increases the wind loads on cladding and components of building envelope and exposes the building c ontents to wind-driven rain. In particular, post-hurricane i nvestigations reports have show n that windborne debris is a significant hazard to glass during wi nd storms. This research aims to investigate the effects of windborne asphalt roof shingles on window glazing. Impact tests were conducted on 3.18 mm (1/8) annealed and 4.76 mm (3/16) annealed gl ass. New and old roof shingle tabs, both full weight and half weight, were considered. Two types of f light modes were considered, autorotation and tumbling. An analysis of variance (ANOVA) was performed on the experimental data to correlate glass thickness, missile weight and momentum required to break the glass. Roofing tile or tile fragments have been al so observed to damage window shutters and the glazing behind them. In this research, a second series of test s were performed to investigate the performance of window shutter systems when s ubjected to the impact of roofing tiles and a

PAGE 13

13 standard 2x4 missile. Impact tests were performed at two diffe rent impact speeds, 20.12 m/s (45 mph) and 15.2 m/s (34 mph), and with two types of installation methods, direct mount method and tracking method. Deflections due to impact of the tile missile and 2x4 lumber were recorded and compared.

PAGE 14

14 CHAPTER 1 INTRODUCTION A breach of the building envelope can lead to a sudden increase in th e net pressu re acting on the roof system and expose the building contents to wind-driven rain (Lin et al, 2007; Minor, 1994). Windborne debris has been established as the principal cause of th is phenomena, after the effects of Hurricane Andrew (1992); as a result, the building design process has been changed to address the debris impact on vari ous components and cladding of th e building envelope so that it maintains its integrity during extreme wind events Modern building codes including the Florida Building Code (FBC, 2004) and International Residential Code (IRC, 2006) require that fenestration and in some cases, wall and roof cl addings, be tested to certify a minimum impact strength standard to survive impacts from windborne debris wh en buildings are located in windborne debris regions. The research presented here focuses on the im pact of shingles on residential glazing and that of concrete tile on shutte r systems. This research was performed at the request of the Hurricane Research Advisory Committee of the Florida Building Commission, which was created to address building failu res resulting from the 2004 hurrica nes that impacted Florida. To complete this research it was necessary to develop two testing apparatuses. A custom shingle launcher was constructe d to propel asphalt roof shingles with sufficient velocity to damage annealed glass specimens that varied in thickness and frontal area Projectiles included new and naturally aged shingles of various sizes and weights. Velocit y, momentum and kinetic energy of the projectile were analyzed to determine thresholds of breakage. A second projectile launcher was constructed to propel conc rete tiles into galvanized steel storm shutters to determine their impact resistance. Duplicate test specimens underwent a

PAGE 15

15 second round of testing using the large missile impact test procedures set forth in FBC 1626.2, which utilizes a piece of 2x4 timber weighing 4.1 kg (9 lb) as a representative missile. In order to better understand the behavior of building components against missile impact during extreme wind events, it was important to understand the characteristics of fluctuating wind pressure and their effect s on building envelope. The following section describes extreme wind behavior on low-rise buildings and the resulting damage due to debris impact. 1.1 Extreme Wind Effects on Low-Rise Buildings During extrem e wind events, the fluctuating pres sure loading that acts on structures is caused by the mechanical turbulence created by the upwind terrain and the flow distortion created by the building. Turbul ent aerodynamic wind effects include the frontal vortex, recirculation zones, shear layers, and flow separation at corners of the building (Figure 1-1). The resultant wind-structure inter action is summarized below (Yea tts and Mehta, 1993; Krishna, 1995; FEMA, 2000): 1. Positive pressures act on windward walls and windward surfaces of steep sloped roofs. The stagnation point will be found at about two-thirds of the height on the windward wall (Cook 1985). Below the stagnation point, wind flows downward and it rolls up into a vortex and travels horizontally outward across the wall. 2. Negative pressures act on leeward walls, side walls, leeward surfaces of steep sloped roofs, and all roof surfaces for low sloped roofs or steep sloped roofs when winds are parallel to the ridge. The side walls are subjected to se paration flow and a reattachment flow. Wind flow separation occurs at the sharp corners a nd edges. This separated wind flow becomes reattached onto the surface, causing reattachment flow. Suction pressure is higher at the corners and edges, and decrea ses downward depending upon th e length-to-width ratio of the bluff body. The leeward wall is usually expose d to the wake region. The wake region is divided into two parts near-wake region (r e-circulating flow im mediately behind the building) and the far-wake region (wind flowi ng downstream and eventu ally blending with boundary layer flow). (Cook 1985). The suction pressure is generally constant on the leeward side. The pressure fluc tuation on the roof is dependent on the roofs shape, pitch and the presence of architectural feat ures like overhangs, or parapets. 3. Windows, doors and other openi ngs are subjected to wind pr essures during extreme wind events and the impact of wind borne missiles.

PAGE 16

16 The present research project focuses on the thir d phenomenon stated above, particularly the impact of windborne roof cover on glazing and shutter systems intend ed for hurricane prone regions. 1.2 Damage Due to Wind Borne Debris The United States sustains billions of dolla rs per year in proper ty and econom ic losses due to extreme wind events such as hurricanes, tornadoes, and winter storms, which cause damage mainly to low-rise residential structures and light comm ercial structures. Pielke and Landsea (1998) estimated that the average ec onomic loss was $4.8 billi on (in 1995 dollars) due to tropical cyclone impacts in United States during 1925-95. Numerous studies of post-hurricane damage sp ecifically cite windborne debris as a major source of damage to the building envelope. The literature on the subject becomes more abundant as Minor (1994), Beason (1984), McDonald (2000) began to record the observations during various windstorm events. They also presented a synopsis of damage observations for various hurricanes such as Celia (1970), Frederic ( 1979), Allen (1981), Alic ia (1983), and Andrew (1992). Reed (1970) observed windborne debris as a principal s ource of damage to windows of high-rise buildings during the Lubbock Storm of May 11, 1970 (Minor 1994). Damage surveys conducted after Hurricane Celia (1970) revealed that the br eakage of windows in downtown Corpus Christi, Texas, was mainly caused due to debris carried by wind. Pieces of roofing material, sheet metal, garbage cans and roof gr avel were observed as glass-breaking agents (Minor 1994). Another notable example of windborne debris damage was in Darwin, Australia, due to Tropical Cyclone Tracy in 1974. Beason et al (1984) investigated the damage caused by Hurricane Alicia (1983 ) in Houston, Texas, and observed that windborne missiles from building roofs were the major cause of damage to architectural glazing systems. The investigators also concluded that building envelope failures caused by windborne de bris generally occurred before

PAGE 17

17 lateral pressure became critical. Following Hurricane Andrew (1992), the FEMA Technical Standards Division assembled a team of engineer s and architects to examine the performance of buildings in the affected area. Oliver and Hanson (1994) observed that the debris impact shattered glazing components. The investigator s also observed that debris from roofing materials, especially clay and concrete roofing tile, was the mo st common type that caused significant damage to building e nvelope systems (Ayscue 1996). After Hurricane Andrew, the 2004 and 2005 Atla ntic hurricane seasons were one of the most costly hurricane seasons on record. In the investigations following Hurricane Charley (2004), researchers found that wi ndborne missiles originated fr om the roofs of residential structures. Damage was observed on several asph alt shingle roofs due to the lack of bonding adhesive. The principal source of windborne debris was the blowingoff of hip or ridge shingles. Tile damage was also observed in the areas of Port Charlotte and Punta Gorda (FEMA 2005a). The blow-off of the tiles along eaves and of th e hip and ridge tiles was documented by FEMA (2005a). The FEMA (FEMA 2005a) report also men tioned that tile or tile fragments easily penetrated through windows. Figur e 1-3 shows the window shutter damage due to strike of tile (Reinhold 2005). In many cases windows were br oken by tiles from a neighbors house (Meloy et al. 2007). Gurley (2006) described how window performa nce during the 2004 storms was related to wind speed, window protection use, and the dominant roof cover type in the neighborhood. The window performance graph is s hown in Figure 1-4 for properties located in the region of the 58-67 m/s (130-150 mph) wi nd gust during Hurricane Charley. The graph clearly indicates that even prot ected windows are susceptible to damage due to a tile strike. FEMA (2005b) also noted that shingles and tiles were blown off during Hurricane Ivan (2004), and they caused damage to unprot ected glazing and shutters.

PAGE 18

18 1.3 Thesis Summary Chapter 2 presents background information on common windborne debris types, missile impact testing standards and previous research pertinent to this research topic. Chapter 3 presents the experimental configuration to te st glazing against shingle missile impact, the apparatus and procedures used dur ing the experiments, and the resu lts of the experiment. Chapter 4 presents the experimental configuration to te st window shutters against tile missile impact and 2x4 missile impact, the apparatus, and procedures and the results of the experiment. Chapter 5 provides the conclusions based on findings in Chapter 3 and Chapter 4. Chapter 5 makes recommendations for future research activities supporti ng this research.

PAGE 19

19 A B Figure 1-1. Wind flow around build ing. A) Elevation. B) Plan. Stagnation point Wind Flow Wake Region Eddies Elevation Stream Lines Reattaching shear layers and vortex g eneration Wind Flow Eddies Plan

PAGE 20

20 Figure 1-2. Windward wall opening caused increase in internal pressure (Side view) Figure 1-3. Window shutter damage due to Spanish tile. (Reinhold 2005) Wind Flow Neg. pressure Pos. pressure Internal Pressure

PAGE 21

21 Figure 1-4. Percentage of ho mes with at least one window damaged as a function of neighborhood roof cover type and window protection. (Gurley 2006).

PAGE 22

22 CHAPTER 2 BACKGROUND Severe windstorm events rou tinely cause significant damage to the building envelope. The impacts of extreme windstorms on the existi ng engineering systems have invited serious attention of engineers in the last four decades. In the previous chapter, the discussion consisted of the breach of the building envelope due to im pacts of windborne debris. Debris can originate from the building itself. The debris sources consis t of roofing materials su ch as shingles, tiles, gravel, inadequately atta ched cladding components such as sheathing and siding, and tree limbs, etc. This chapter further di scusses common windborne debris types as a cause of the extreme wind effects on the building envelope. The components of the building envelope such as windows, doors, curtain walls, and storm shutters play an important role in impr oving the performance of the building envelope and reducing the damage due to windborne debris. This chapter presents an overview of current test standards to evaluate the perfor mance of the building envelope components against debris impact and also presents the previous research on windborne debris impacts on window glass. 2.1 Common Windborne Debris Types Minor (1994) analyzed the window dam a ge mechanism during wind storms and classified windborne debris as ei ther small or large missiles. Th e classification is based on the debriss potential impact eleva tions on the building envelope. Large missiles can impact the building envelope near ground level, while sma ll missiles can impact high elevations of a building faade. Unanwa and McDonald (2000) clas sified windborne debris into light-, mediumand heavy-weight missiles, according to their observed damage performance. Wills et al. (2002) classified windborne debris into three categories based on size and shapes (dimensions): compact objects (3D) such as cubic and spherica l roof gravels; sheet

PAGE 23

23 objects (2D) such as plywood, corrugated iron, roof tiles and shingles; and rod objects (1D) such as bamboo poles and 2x4 timber. FEMA (2000) also lists the classificatio n of debris types, examples and expected damage as shown in Table 2-1. The next section presents current test sta ndards for testing the building envelope products against debris impact. The test standards are based on the debris clas sification given above. 2.2 Windborne Missile Impact Test Standards 2.2.1 History of Windborne Missile Test Standards Current windborne debris test standards have evolved from experience and research over the past 40 years. In 1974, Tropical Cyclone Tr acy struck Darwin, Australia. The post-event report indicated that most of the damage to bui ldings was caused due to a sudden increase in internal pressure, followed by the failure of windward windows due to windborne debris damage and the fatigue failure of cladding and metal co nnections under fluctuating pressure (Minor 1994). The first test standard for missile impact appeared shortly thereafter in the Darwin Area Building Manual (Minor 1994). A 4 kg (9 lb) 51m m x 102 mm (2x4) timber appeared as a design missile in the building code. In 1983, a windborne debris impact standard using a 4100 gm (9 lb) 51 mm x 102 mm (2x4) timber as a representative missile was proposed in the Southern Building Code Congress Internationa l (SBCCI 1983). The proposal was opposed by major glass manufacturers and was eventually de feated (Hattis 2006). The first building code in the U.S. to incorporate a windborne debris impact standard was the South Florida Building Code (Minor 2005). The standard was adopted in 1993, primarily as a result of the damage caused by Hurricane Andrew (1992) and Hu rricane Alicia (1983). The Dade County Building Code Committee initially selected roofing tile as a representative missile, since it was the most prevalent debris in Hurricane Andrew. However, it was observed that it would be difficult to define a representative roofing tile for use in test standards because there were many types of

PAGE 24

24 roofing tiles. It was purported that it would be difficult to propel a piece of roofing tile, repeatedly, in the same orientation and at the same speed as a part of a standard test. Ultimately, the committee recommended a 4 kg (9 lb) 51 mm x 102 mm (2x4) timber traveling at 15 m/sec (50 ft/sec) as representative of a large missile in standard tests (Min or 1994). Broward County, Florida, also adopted the windbor ne debris standard in 1993. These changes were included into Dade County and Broward County editions of th e South Florida Building Code (SFBC). Palm Beach County also adopted windborne debris standard in 1994. It was later incorporated into the Standard Building Code (SBC). 2.2.2 American Society of Test ing and Materials (ASTM) ASTM is an international orga nization that develops technical standards for a wide range of m aterials, products, and systems using a cons ensus process. ASTM provides two protocols for testing products for miss ile impact resistance. 2.2.2.1 The ASTM E 1886-02 (Standard test method for p erformance of exterior windows, curtain walls, doors and storm shutters im pacted by missile(s) and exposed cyclic pressure differentials) The test standard outlines a method to test products using a missile propulsion device and an air-pressure cycling testing chamber to obta in the conditions similar to debris impact and fluctuating pressures in windstorm events. An air cannon is used to propel small or large missiles to test the products. The test chamber is pressuri zed with a controllable blower or compressed air supply or vacuum chamber to replicate the effect s of static pressure differentials on the test products. The test method evaluates the performan ce of specimens against the impact of small and large missiles. The representative small missile is a 2 gm (%) steel ball, with an 8 mm nominal diameter, and its impact speed is between 40% and 85% of the basic wind speed. The representative large miss ile is a No. 2 or better Southern Yellow Pine or Douglas Fir 2x4 with a

PAGE 25

25 mass between 2.05 kg 0.1kg and 6.8 kg 0.1kg. Its length is between 1.2m 0.1m and 4.0m 0.1m. Its impact speed is between 10% and 55% of the basic wind speed. The specified number of cycles of positive and negative static pressu re differential is given in the Table 2-2. 2.2.2.2 The ASTM E 1996-03 (Standard Test Metho d for performance of exterior w indows, curtain walls, doors, and storm shutters impa cted by windborne debris in a hurricane) The test standard evaluates th e performance of the exterior windows, curtain walls, doors and storm shutters intended for buildings located in hurricane-prone areas. This standard is similar to ASTM E 1886 but provides additional de tails about the use of missiles of different weights with varying impact spee d. The test products are subject ed to missile impacts based on basic wind speed, level of protection, and assembly height. The standard defines four different wind zones based on basic wind spee d as given in Table 2-3. It al so defines three levels of protection. Enhanced protection, for buildings and structur es designated as essen tial facilities includes hospitals, emergency treatment facilities, em ergency shelters, power-generating stations, national defense structures, etc. Basic protection, for buildings and structures not categorized as enhanced protection and unprotected. Unprotected, such as buildings and structures subjected to a low hazard to human life in a windstorm, for example, agricultural facilitie s, storage facilities, certain temporary facilities, etc. The missile level, its corresponding missile we ight, and impact speed are given in Table 2-4. Products are tested as per Table 2-5. Three test specimens are subjected to large missile impacts and small missile impacts. The specifications for large and small missiles are based on ASTM E 1886. The large missile test requires one impact at products cent er and another at its corner as shown in Figure 2-1. The small missile test consists of a total of 30 steel ball impacts, with 10 steel ball impacts at a time, as shown in Figure 2-2.

PAGE 26

26 The test specimen should resist the large or small missile impacts or both with no tear longer than 130 mm or no opening formed through which a 76 mm diameter solid sphere can freely pass, when evaluated upon completion of mi ssile impacts and test loading for wind zones 1, 2 and 3. For wind zone 4, the test specimen should resist the large or sm all missile impacts or both without penetration of the inne r plane of the infill or shutter assembly as well as the criteria of wind zone 1, 2, and 3. 2.2.3 Florida Building Code (FBC) (TAS 201: Impact Test Procedure) The Florida Building Code is based on the national m odel building code and national consensus standards and was developed by the Fl orida Building Commission. It superseded all local codes in Florida and is effective from 2001 as per Chapter 553, Florida Statues Building Construction Standards. The structural requirem ents of the South Flor ida Building Code were incorporated into special sect ions of the code for the High Velocity Hurricane Zone (HVHZ) (FBC 2001). The test standard for evaluating th e performance of building envelope products under the impact of windborne missiles as per FBC is given below. The test determines the windborne debris imp act resistance of exterior windows, glazing, exterior doors, skylights and storm shutters. Three identical test specimens are repeatedly struck with large or small missiles fired from a missile propulsion device. According to FBC 1626.2.4 the large missile test requires that a soli d, nominal 4.1 kg 51 mm x 102 mm (2x4) #2 surface dry Southern Pine lumber be fired at 15.2 m/s (50 fps) The test consists of two impacts one at the products center and the other at the corner. The test is applicab le for openings less than 9.1m (30 ft) above the ground, according to FBC 1626.2.1. According to FBC 1626.3.4, the small missile test requires that a 2 gm so lid steel sphere be fired at 40 m/ s (130 fps). It consists of three series of 10 repeated impacts. The first impact series is at the speci mens center, the second

PAGE 27

27 occurs at a center of large dimension, and the th ird occurs at a corner of specimen. The test is applicable to openings higher than 9.1 m (30 ft) above the ground. If all test specimens have successfully co mpleted TAS 201, they are subjected to cyclic pressure loading as per FBC 1625.4. The test specimen should suffer no resulting failure or distress and should have recovery of 90% over maximum deflection. 2.2.4 American Architectural Manufacturers Association (AAMA) The Am erican Architectural Manufacturers Association (AAMA) is an industry sponsored organization that has established many of the industry standards that are commonly used today. AAMA has develope d two specifications for testi ng the building components under the impact of windborne debris. 2.2.4.1 The AAMA 506 (Voluntary specifications for hurricane impact and cycle testing of fenestration product) This specification evaluates the ability of windows, doors, skylights, storefront and curtain walls, and sliding glass doors to withstan d the im pact and pressure cycling associated with hurricane conditions. The requirements of the test apparatus for large/small missile impacts, test specimens and test procedures addre ss the following standards: ASTM E 1886, ASTM E 1996, AAMA 501, AAMA/WDMA/CSA 101/I.S.2/ A-440 and AAMA/NWWD A 101/I.S.2. 2.2.4.2 The AAMA/WDMA/CSA 101/I.S.2/A 440 (S tandard specification for w indows, doors and unit skylights) Clause 5.3.10 (Impact performance) For checking the performan ce of windows, doors and unit sk ylights when subjected to windborne debris impact in high wind events, the specimens should comply with either ASTM E 1996 or AAMA 506. 2.2.5 American Society of Civil Engineers (ASCE 7-05) The ASCE 7 standard provides m inimum load requirements for the design of buildings and other structures that are subject to building code require ments, including wind effects on

PAGE 28

28 structures. ASCE 7-05 defines windborne debris re gions as areas within hurricane prone regions located within 1.61 km (1 mile) of the coastal mean high water line where the basic wind speed is equal to or greater than 49.17 m/s (110 mph) or in Hawaii or areas where the basic wind speed is equal to greater than 5 3.64 m/s (120 mph). According to section 6.5.9.3 of ASCE 7-05, glazing in windborne debris regions should be impact-resistant or s hould be protected with an impact-resistant covering. Either of these should comply with requirements set forth in ASTM E 1886 and ASTM E 1996. 2.2.6 Standard Building Code (SSTD 12-94) (S BCCI Test Standard for Determining Impact Resistance from Windborne Debris) The Building Officials Associat ion of Pal m Beach County, Florida, proposed the SSTD 12-94 standard. This standard evaluated the performance of glazed opening systems and storm shutter systems subjected to impacts of windborne debris and cyclic pressure conditions, as in high-wind events. The specimens are repeatedly stru ck with small or large missiles fired from a missile propulsion device. As per the standard, the large missile test is conducted using 2x4 timber specimen. The missiles weight should be 4.1 kg (9 lb), and its length should be 2.59 m (8.5 ft). The impact speed should be between 15.2 and 15.85 m/s. The test specimen should be impacted once at its center and once at a corner. The small missile test is conducted using 2 gm steel balls. The impact speed should be between 39.62 and 40.23 m/ s. The test specimen should receive three series of 10 repeated impacts. The first series should be at the speci mens center, the second should be at a center of large dimension, and the th ird should be at a corn er of the specimen. Once the test specimens are subj ected to large/small missile impacts, the cyclic pressure loading has to be applied. The specimen should be subjected to the large/small missile impacts

PAGE 29

29 and resist the cyclic pressure loading with no crack forming longer than 0.13 m (5) through which air can pass or with no opening through which a 0.077 m (3) diameter sphere can pass. 2.2.7 International Building Code (IBC) a nd I nternational Residential Code (IRC) The Building Officials Code Administrators Internationa l (BOCA), Southern Building Code Congress International (SBCCI) and Inte rnational Conference of Building Officials (ICBO) combined to create the International Bu ilding Code (IBC), which is maintained by the International Code Council (ICC) Section 1609 of the IBC contai ns wind-load provisions and specifies following the require ments of ASTM E 1886 and ASTM E 1996 for glazing protection in windborne debris regions. It al so specifies using a large missile impact test as per ASTM E 1996, if glazed openings are located less than 9.144 m (30 ft) from the ground; it specifies using the small missile impact test as per ASTM E 1886, if glazed openings are located higher than 9.144 m (30 ft). Section R613.7 of the Intern ational Residential Code sp ecifies use of ASTM E 1886, ASTM E 1996 and AAMA 506 for testing exterior windows, doors or other fenestration products if buildings are located in windborne debris regions. 2.2.8 The ICC/NSSA Standard on the Design a nd Construction of Storm Shelters (Draft) The scope o f this standard is meant for the design and construction of shelters for highwind events like hurricanes, tornadoes. Storm ev ents produce high winds and flying debris, and so it is important to test components of the shel ter envelope against windborne missile impacts. One section of the standard outlines the procedure for conducting im pact and pressure testing for components of the shelter envelope. It specifies using ASTM E 1886 for the missile impact test apparatus. The impact missile s hould be 2x4 lumber. Its weight should be 4.1 kg (9 lb), and its length should be 2.438 m 0.102 m (8 ft 4 in). Missile impact speed should be 0.4 times the shelter design wind speed for impacting vertical shelter surfaces, and 0.1 times the shelter design

PAGE 30

30 wind speed for impacting horizontal shelter su rfaces. Windows, other glazed openings, and shutters should be impacted at the specimens center and also at its corner. No more than two impacts should be made on the test specimen. Any perforation of the test ed component of the shelter envelope by the design missile is deemed to constitute a failure. 2.3 Previous Research The scien tific basis of the standards identified in the previous section is addressed in this section. The research most relevant to this study was conducted by Texas Tech University and the NAHB Research Center. 2.3.1 Texas Tech University Beason (197 4) investigated the breakage ch aracteristics of glass specimens when subjected to small missile impacts. He considered two different thicknesses of annealed glass, 2.38 mm (3/32) and 6.35 mm (). Test specimen s were subjected to missile impacts of 0.61 gm and 5.55 gm steel balls, which were common re presentatives of roof gravel debris in wind storm events. Using analysis of variance techni ques (ANOVA), it was determined that missile size was a significant factor for the breakage of gl ass, compared with glass area, glass type, and glass thickness. It was also de termined that 6.35 mm () glass was as vulnerable to missile impact damage as 2.38 mm (3/32) glass. Harris (1978) also performed e xperiments on different thicknesses of glass specimens using 5.55 gm and 28.14 gm missiles, and concluded that missile mass was the most important damage indicator. Bole (1999) investigated the windborne missile impact on window glass at Texas Tech University. The goal of the project was to determ ine whether the kinetic energy of the projectile was sufficient to define the outcome of missile imp act tests. The project consisted of impacting window glass using common debris impact crit eria as per ASTM E 1886 and SSTD 12. Bole (1999) tested 6.35 mm () annealed glass, 6.35 mm () and 4.76 mm (3/16) heat

PAGE 31

31 strengthened glass, 6.35 mm () annealed monolithic glass, and 6.35 mm () tempered monolithic glass using 2x4 timber missiles. Acco rding to ASTM E 1886, the large missile test criteria specifies using 4.1 kg (9 lb), 2x4 timber missile with an impact speed of 15.2 m/s (50 fps), which is equivalent to 48.4 kg-m (350 ft-l b) of kinetic energy. Glass specimens were impacted by 2x4 timber missiles of 2.04 kg (4.5 lb), 4.1 kg (9 lb), and 8.16 kg (18 lb) shot from air cannon. The impacts were conducted so that they would produce the same kinetic energy of 350 ft-lb by varying the impact velocity. Bole no ted data pertaining to motion of the objects involved in the impact. Bole analyzed the data an d calculated the angular ve locity of the glazing support frame, kinetic energy before and after impact, and angular momentum. The results of these experiments showed that three different missiles of diff erent mass but the same kinetic energy upon impact produced vastly different resu lts. Bole (1999) concluded that the missiles kinetic energy upon impact cannot predict the outc ome of the impact, and also mentioned that energy loss occurred during a missile impact on window glass. 2.3.2 The NAHB Research Center The National Association of Home Builders (NAHB) Research Center performed impact testing on glass specimens using field observe d and standard missile types to represent windborne debris. The goal of the research was to determine a probabilistic relationship between impact magnitude and glass breakage of typical residential annealed glass using both roof shingle and 2x4 missiles (NAHB 2002). Specimens consisted of 0.61 m (2) x 0.61 m (2) and 0.61 m (2) x 1.22 m (4) glass panels at 2.38 mm (3 /32) and 3.97 mm (5/32) thicknesses. All tests were conducted on annealed glass. Th e study found that a common glazing material provided non-negligible resistance to impacts from 2x4 and roof shingle missiles. It was also observed that when glass specimens were subjected to the impact of roof shingles, the resistance of glass specimens increased pr oportionally with thickness. The im pact resistance of 0.61 m (2)

PAGE 32

32 x 1.22 m (4) panels was less as compared to that of 0.61 m (2) X 0.61 m (2) panels when subjected to shingle missiles. The results also showed that the performance of most glass specimen types was similar for a 2x4 lumber missile. 2.4 Windborne Debris Damage Models W ills et al. (2002) developed a theoretical model for the UN International Decade for Natural Disaster Reduction. He indicated the da mage potential of flying debris is based on the assumption that the amount of damage sustaine d is proportional to the missiles kinetic energy. He defined the relationship between the body dimension and the wind speed (V) at which flight occurred and the objects became airborne missiles. The flight speed threshold for compact, sheet and rod objects were, respectively, as follows: )(*)(*)*(*5.0f air mC I gl V (2-1) )(*)(***2f air mC I gtV (2-2) )(*)(*)*(*5.0f air mC I d V (2-3) Where l = characteristic length of compact object, t = thickness of sheet object, d = effective diameter of rod-type object, m = density of object material, a = air density, Cf = aerodynamic coefficient, I = fixing strength integrity parameter (for objects resti ng on the ground I=1), g = gravitational constant. A seri es of wind-tunnel experiments we re conducted at Colorado State University to validate the model for cubes of vari ous material densities and the model for various types of sheet. The damage caused due to a single missile impact can be represented by the kinetic energy equation, 23***2/1 Vlm D (2-4)

PAGE 33

33 The equation indicates that damage is directly proportional to the velocity (V) and size of missile. The model indicated that less-dense, co mpact objects became airborne very easily and had more damage potential at a given wind speed. It was also observed that sheet and rod objects had generally more dama ge potential than compact objects. (Holmes 2002). Twisdale et al. (FEMA 2003) developed a wi ndborne debris model to estimate impact risk in residential environments. The model inco rporates missile sources and a transport model for the flight of missiles. The model focuses on debris produced from th e roofs of residential structures, includes debris as roof tiles, roof shingles, roof sheathing panels, 2x4 lumber, whole roofs, and roof canopies. The model provides information on th e total number of impacts to residential building components, impact speed of object, angle and orientation of object when it strikes the building; the model calculates the as sociated energy and momentum of the missile. The model also calculates the proba bility of damage to an opening, (PV(D)) for wind speed V, ))](1(*exp[1)( dPq DPv (2-5) Where d = energy or momentum level assumed to produce damage, q = fraction of building surface occupied by windows and glass doors, = mean number of missile impacts per building. The probability of no damage R is given by )(1 DPvR (2-6) The model generates the probability curves as a function of wind speed, and specifies the probability of exceeding a threshold value of energy or momentum for a window or door. 2.5 Summary This chapter discusses the causes and type s of common windborne debris. Section 2.2 provides information about current test standard s for testing building en velope products against missile impact. Section 2.3 presents the past re search projects pertinent to our research. Next,

PAGE 34

34 chapter 3 discusses the experime ntal procedure concerning shingl e missile impacts on glazing, the apparatus and procedure used during the experiments and results of the experiments.

PAGE 35

35 Table 2-1. Windborne missiles and classification (FEMA 2000) Missile Size Common examples of debris Expected damage Small (Light Weight) A ggregate roof surfacing, pieces of trees, pieces of wood framing members, bricks Broken doors, windows, and other glazing, some light roof covering damage Medium (Medium Weight) Appliances, HVAC units, long wood framing members, steel decking, trash containers, furniture Considerable damage to walls, roof coverings and roof structures Large (Heavy Weight) Structural columns, beams, joists, roof trusses, large tanks, automobiles, trees Damage to wall and roof framing members and structural systems Table 2-2. Cyclic static air pressure loading (ASTM E1886-02) Loading Sequence Loading Direction Air Pressu re Cycles Number of Air Pressure Cycles 1 Positive 0.2 to 0.5 Ppos 3500 2 Positive 0.0 to 0.6 Ppos 300 3 Positive 0.5 to 0.8 Ppos 600 4 Positive 0.3 to 1.0 Ppos 100 5 Negative 0.3 to 1.0 Pneg 50 6 Negative 0.5 to 0.8 Pneg 1050 7 Negative 0.0 to 0.6 Pneg 50 8 Negative 0.2 to 0.5 Pneg 3350 Table 2-3. Wind zone cla ssification (ASTM E1996-03) Wind Zone Definitions I 49 m/sec (110 mph) basic wind speed < 54 m/sec (120 mph) and Hawaii II 54 m/sec (120 mph) basic wind speed < 58 m/sec (130 mph) at greater than 1.6 km from the coastline. III 58 m/sec (130 mph) basic wind speed 63 m/sec (140 mph), or 54 m/sec (120 mph) basic wind speed 63 m/sec (140 mph) and within 1.6 km of the coastline. IV Basic wind speed > 63 m/sec (140 mph) Table 2-4. Applicable missile (ASTM E1996-03) Missile Level Missiles Impact Speed (m/sec) A 2 gm 5% steel ball 39.62 (130 fps) B 910 gm 100 gm (2.0 lb 0.25 lb) 2x4 in 15.25 (50 fps) C 2050 gm 100 gm (4.5 lb 0.25 lb) 2x4 in 12.19 (40 fps) D 4100 gm 100 gm (9 lb 0.25 lb) 2x4 in 15.25 (50 fps) E 4100 gm 100 gm (9 lb 0.25 lb) 2x4 in 24.38 (80 fps)

PAGE 36

36 Table 2-5. Missile impact test for appropria te level of building pr otection (ASTM E1996-03) Level of Protection Enhanced Prot ection Basic Protec tion Unprotected Assembly Height 9.1 m (30 ft) >9.1 m (30 ft) 9.1 m (30 ft) >9.1 m (30 ft) 9.1 m (30 ft) >9.1 m (30 ft) Wind Zone I D D C A None None Wind Zone II D D C A None None Wind Zone III E D D A None None Wind Zone IV E D D A None None

PAGE 37

37 Only applicable in Wind zone 4 Figure 2-1. Location of large missile imp acts on three test specimens (ASTM E1996-03). Figure 2-2. Location of small missile impacts on three test specimens (ASTM E1996-03).

PAGE 38

38 CHAPTER 3 IMPACT OF SHINGLE MISSILES ON GLAZING This first component of the research f ocuses on the eff ects of windborne asphalt roof shingles impacting window glass. The study includes an experimental evaluation of the damage threshold of residential glass impacted by roof sh ingles. This chapter presents the experimental configuration and protocol used in this study and provides th e results of the testing. 3.1 Experimental Configuration In order to simulate windborne asphalt shi ngle impacts on glazing, an apparatus capable of recreating missile impacts had to be constructed. Its principal components include the shingle launcher, a specimen box and glazing support frame, and a high speed camera. Details of these components are presented in the following sections. 3.1.1 Shingle Launcher The shingle launcher was designed to propel as phalt shingle missiles of various sizes at various speeds over a short distance into a gla ss specimen. The design was inspired by a baseball pitching machine. Two vertically oriented rubbe r tires of 0.19 m (7.5 in) radius contact each other at the treads, and a 0.75 KW (1 hp) Franklin Electric AC induction motor spins the bottom tire, which causes the top tire to contra-rotate (F igure 3-2). The shingle specimens are slowly fed into the gap on a flat plate (tray) into the grip of the spinning tires. The rotation of the tires accelerates the shingle until it is expelled on the opposite side. A motor controller allows the angular velocity of the tires to be adjusted from 250 to 2400 RPM, which in turn determines the velocity of the projectile. The tray can be adjusted to create at least two flight modes: (1) one axis autorotation (Autorotation mo de) and (2) tumbling, the latter of which causes the shingle to strike the target on its flat si de. The impact location can be ch anged by rotating and tilting the shingle launcher as required.

PAGE 39

39 3.1.2 Specimen Box and Glazing Support Frame A 1.42 m (56 in) deep x 1.22 m (48 in) wi de x 2.44 m (96 in) tall wood frame box sheathed in 1.27 cm plywood was built to house th e glazing support frame and to contain the broken glass for easy disposal. On the side faci ng the shingle launcher, the specimen box has a 1.03 m (40.5 in) wide x 1.14 m (45 in) high ope ning through which the sh ingle passes (Figure 3.1). A glazing support frame holds the glass inside the box. It consists of a fixed wood frame and removable steel frame that supports different sizes and thicknesses of glass. During testing glass specimens are clamped in place between st rips of weather-stripping. The frame provides continuous support around the top and bottom of the glass pane. 3.1.3 A High-Speed Camera A Vision Research Phantom V5.2 high speed camera captured color footage of the shingle missile projectile in f light to determine the projectile velocity. The camera recorded 1000 frames per second after it was configured fo r 1152 X 896 pixel frame resolution. A 3.05 m (10 ft) long x 0.20 m (8 in) wide board marked with vertical reference at 0.025 m (1 in) intervals was located on the opposite side such that the shingle passed be tween the board and camera. Reference lines were also marked on the shingl e to quantify the angular velocity. Appendix B provides a sample impact velocity calculation. 3.2 Test Materials The test specimen matrix consisted of ann ealed glass of varying thicknesses and sizes. All glass specimens were manufactured by Shea s Glass Company located in Gainesville, Florida. Four types of asphalt shingle were used. The new shingles were 3-tab shingles manufactured by Tamko Building Products, whic h conform to the ASTM D 3462 requirements for asphalt shingles made from glass felt and surfaced with mineral granules. Used shingles were acquired during a re-roofing of a residential home in south Florida. The age of the shingle was

PAGE 40

40 estimated to be on the order of 20-30 years. Full -weight and half-weight sh ingles were used as missiles. To make the half-weight shingles, th e full-weight shingles were cut as shown in Appendix D. The test specimen matrix is summarized in Table 3-1. 3.3 Experimental Procedure 3.3.1 Installation of Test Specimen The first step consists of clamping and s ecuring the glass specimen into glazing support frame. Weather-stripping is used to provide co ntinuous support at top and bottom of the glass pane. 3.3.2 Preparation of Shingle Missile Each piece of shingle was assigned a unique identification number and its weight was measured. 3.3.3 Missile Impact on Glazing It was not cost effective to test a new gl ass specimen for each test. Discarding unbroken specimens would have significantly increased the co st of the experiment. Thus the investigator adopted the following approach. The shingle was placed on a flat plate (tray) on the shingle launcher. The motor RPM was brought to the required speed and recorded. Next the shingle was slowly fed into the gap between the tires. After impact, the nature of dama ge (if any) on the glass was also recorded, for example, a crack or shatter. If a break occurred, the next test specimen was mounted and tested at that specified RPM. If a break did not occur, the motor speed was increased by 50 RPM and the test was repeated. This process occurred until the glass broke. Once the glass broke, a new glass specimen was reloaded and the test was repeated until failure. Thus, some conservativeness is built into the procedure, as the specimens usua lly failed 1-2 iterations after initial impact.

PAGE 41

41 3.3.4 Interpretation Ideally, slowly increasing the RPM (speed) and using repeat impacting until failure identifies the lowest speed at which that specim en will break from impact of the test shingle. However, this is only the case if damage does not accumulate in the specimen from impacts at lower speeds prior to breakage. The test protocol required that the glass specimen be inspected for visible damage of any kind. Additional imp acts at higher speeds were only conducted if no such damage can be identified. Visual inspec tion is not a foolproof means of determining whether the specimen is damaged. The purpose of repeating the damage impact speed on a new specimen after the original specimen breaks is to establish whether unseen damage accumulation from multiple impacts on the first specimen could be a factor in its fi nal breakage speed. If damage accumulation is not a factor (the desired circumstance), then subseque nt new glass specimens will break at a shingle speed at, or close to, the damage speed of the first sample. The failure of a second specimen to break at th e damage speed of the first specimen in a given test series does not prove that damage accumulation was a factor. Natural variability in glass and shingle specimens, impa ct location, and other factors will render the damage impact speed a random variable that will be uncertain ev en with all controllable factors precisely the same. Over the course of many test series, a pattern must emerge where the second specimen usually survives the impact speed of the first specimen in order for damage accumulation to be considered a factor. No such pattern has emerged in the existing dataset. Although the second specimen in several test series does survive th e damage speed of the first specimen, in many other test series the second speci men breaks from first impact at the speed of the first specimen that endured multiple incrementally faster impacts.

PAGE 42

42 The breaking speeds of individual glass sp ecimen represent random samples of the minimum-speed-to-damage random variable. Howe ver, it is not appropriate to use those specimens that broke at first impact as samples of this variable. That is, the impact test that closes any given test series is not to be us ed as a minimum-speed-to-damage random sample. Since there was no incremental speed increase on such specimens, they may well have failed at a speed lower than the single impact test speed. Th e role of these specimens, as defined above, is to provide a means to evaluate the potential in fluence of damage accumulation in the previous specimens. 3.4 Results The sample data worksheet is shown in Appendix A. The relationship between the motor RPM and actual shingle speed was calibrated us ing a high-speed camera. Appendix B shows the calculations for the coefficient of grip. The coeffi cient of grip relates the tangential speed of the wheels to the shingle coming o ff the launcher. Appendix C show s the glass breakage velocity with due consideration of coefficient of grip. Using Equation 3-1, the impact momentum of the shingle was calculated. vm Momentum (3-1) Where m = mass of shingle, v = velocity of shingle at which glass breaks. Table 3-2 lists the observed momentum values. The kinetic energy of the missile was also calculated using Equation 3-2. vvm rgy KineticEne *** 2 1 (3-2) where m = mass of shingle, v = velocity of shingle at which glass breaks. The values are provided in Table 3-3.

PAGE 43

43 3.5 Discussion of Results From the data collected from the above experi ments, statistical analysis was performed. Based on ANOVA analysis, following inte rpretations may be concluded. A one-way ANOVA test was performed to dete rmine if the mean momentum required to break the glass varied with gl ass thickness. As shown in Tabl e 3-4, the F value is very large compared with the critical F value. We can reject the nu ll hypothesis that both groups perform equally. Thus the momentum re quired to break different thicknesses of glass differs significantly. The mean breakage velocity is 1.47 times higher for 4.76 mm (3/16 in) glass compared with 3.18 mm (1/8 in) glass. As glass thickness increases, the momentum required to break the glass also increases. A one-way ANOVA test was performed to dete rmine if the mean momentum required to break the glass varied with the glass size. As shown in Table 3-5, the F value is very small compared with the critical F value. We can accept the null hypothesis that both groups perform equally. The mean threshold moment um is 4.71 kg*m/sec and 4.8 kg*m/sec for 2x2 and 2x4 glass, respectively. Thus, for the ra nge of frontal areas tested, the momentum threshold is not a function of specimen size. A one-way ANOVA test was performed to dete rmine if the mean momentum required to break the glass varied with the size and wei ght of shingle. As shown in Table 3-6 and Table 3-9, the F value is large compared to the critical F value. We can reject the null hypothesis that both groups perf orm equally. It would also ap pear that the shingles of different weight do not have same effect for determining momentum to break the glass. A one-way ANOVA test was performed to dete rmine if the mean momentum required to break the glass varied with the age of the sh ingle missile. As shown in Table 3-7 and Table 3-8, the F values are low compared to th e critical F values. We can accept the null hypothesis that both groups perf orm equally. The results indica te that the difference in breakage threshold between new and old shingles is insignificant. A one-way ANOVA test was performed to dete rmine if the mean momentum required to break the glass varied with the flight mode of shingle missile As shown in Table 3-10, the F value is low compared to the critical F va lue. We can accept the null hypothesis that both groups perform equally. The results indicate th at the difference in breakage threshold between Autorotation and Tumbling mode of flight is insignificant. Conclusions based on the results for the testing are presented in Chapter 5.

PAGE 44

44 Table 3-1. Test specimen matrix Group Test specimen Aspect ratio (hXw) Number of specimens Type of shingle Mode of flight 1 0.61 m (2 ft) x 0.61 m (2 ft) 3.18 mm (1/8 in) 1:1 20 Full weight new shingle Autorotation 2 0.61 m (2 ft) X 1.22 m (4 ft) 3.18 mm (1/8 in) 2:1 11 Full weight new shingle Autorotation 3 0.61 m (2 ft) x 0.61 m (2 ft) 3.18 mm (1/8 in) 1:1 20 Half weight new shingle Autorotation 4 0.61 m (2 ft) x 0.61 m (2 ft) 3.18 mm (1/8 in) 1:1 21 Full weight old shingle Autorotation 5 0.61 m (2 ft) x 0.61 m (2 ft) 3.18 mm (1/8 in) 1:1 09 Half weight old shingle Autorotation 6 0.61 m (2 ft) x 0.61 m (2 ft) 4.76 mm (3/16 in) 1:1 12 Full weight new shingle Autorotation 7 0.61 m (2 ft) x 0.61 m (2 ft) 3.18 mm (1/8 in) 1:1 11 Full weight new shingle Tumbling

PAGE 45

45 Table 3-2. Threshold momentum for various glass specimens Momentum (kg*m/sec) (momentum = m*v) Mode of flight Autorotation Tumbling 3.18 mm (1/8 in) Annealed glass (2x2) 3.18 mm (1/8 in) Annealed glass(2x4) 3.18 mm (1/8 in) Annealed glass(2x2) 3.18 mm (1/8 in) Annealed glass(2x2) 3.18 mm (1/8 in) Annealed glass(2x2) 4.76 mm (3/16 in) Annealed glass(2x2) 3.18 mm (1/8 in) Annealed glass(2x2) Full weight new shingle Full weight new shingle Half weight new shingle Full weight old shingle Half weight old shingle Full weight new shingle Full weight new shingle 2.90 3.59 2.35 3.02 2.48 5.96 3.35 3.59 4.56 2.29 3.14 3.13 6.28 3.90 3.86 4.83 3.06 3.36 3.25 6.52 4.47 4.51 4.83 3.33 4.28 3.44 6.68 4.36 4.51 4.83 3.25 4.89 4.10 6.59 4.81 4.51 5.09 3.63 5.13 4.58 6.59 4.99 4.71 5.54 4.21 5.54 4.66 6.99 5.15 5.72 4.20 5.20 7.63 5.54 4.07 6.20 8.27 5.41 4.70 6.34 5.72 4.58 6.51 6.12 4.25 6.42 4.43 7.04 5.09 5.09

PAGE 46

46 Table 3-3. Threshold kinetic energy for various glass specimens Kinetic Energy (kg*m2/sec2) Mode of flight Autorotation Tumbling 3.18 mm (1/8 in) Annealed glass (2x2) 3.18 mm (1/8 in) Annealed glass(2x4) 3.18 mm (1/8 in) Annealed glass(2x2) 3.18 mm (1/8 in) Annealed glass(2x2) 3.18 mm (1/8 in) Annealed glass(2x2) 4.76 mm (3/16 in) Annealed glass(2x2) 3.18 mm (1/8 in) Annealed glass(2x2) Full weight new shingle Full weight new shingle Half weight new shingle Full weight old shingle Half weight old shingle Full weight new shingle Full weight new shingle 10.50 15.88 13.12 12.15 15.03 45.61 14.04 15.88 25.72 12.81 12.63 23.33 50.54 17.71 18.66 29.16 22.77 14.90 25.71 52.48 24.96 25.40 29.16 26.34 24.13 28.82 56.43 24.34 25.40 29.16 25.71 31.52 42.01 55.72 28.53 25.40 32.76 32.12 35.11 51.24 55.72 29.59 28.43 37.92 41.15 37.92 54.25 61.94 33.17 41.46 43.06 35.58 73.71 37.92 43.62 49.89 86.51 36.98 52.49 53.58 41.46 51.24 55.01 46.78 47.49 54.29 51.53 65.12 61.61 61.61 Table 3-4. ANOVA test between 0.61 m (2 ft) x 0.61 m (2 ft) x 3.18 mm (1/8 in) glass and 0.61 m (2 ft) x 0.61 m (2 ft) x 4.76 mm (3/16 in) glass using full-weight new shingle S u m m a r y Groups Count Sum Average Variance Group 1 12 56.53 4.71 0.89 Group 6 9 61.51 6.83 0.50 ANOVA Source of variation SS df MS F P-value F critical Between groups 23.19 1 23.19 31.96 1.89E-05 4.38 Within groups 13.79 19 0.73 Total 36.98 20

PAGE 47

47 Table3-5. ANOVA test between 0.61 m (2 ft) x 0.61 m (2 ft) x 3.18 mm (1/8 in) glass and 0.61 m (2 ft) x 1.22 m (4 ft) x 3.18 mm (1/8 in) glass using full-weight new shingle S u m m a r y Groups Count Sum Average Variance Group 1 12 56.53 4.71 0.89 Group 2 8 38.99 4.87 0.42 ANOVA Source of variation SS df MS F P-value F critical Between groups 0.13 1 0.13 0.18 0.67 4.41 Within groups 12.71 18 0.70 Total 12.84 19 Table 3-6. ANOVA test between full-weight new shingle and half -weight new shingle for 0.61 m (2 ft) x 0.61 m (2 ft) x 3.18 mm (1/8 in) glass S u m m a r y Groups Count Sum Average Variance Group 1 12 56.53 4.71 0.89 Group 3 15 58.53 3.90 0.79 ANOVA Source of variation SS Df MS F P-value F critical Between groups 4.36 1 4.36 5.24 0.030 4.24 Within groups 20.83 25 0.83 Total 25.19 26 Table 3-7. ANOVA test between full-weight new shingle and fullweight old roof shingle for 0.61 m (2 ft) x 0.61 m (2 ft) x 3.18 mm (1/8 in) glass S u m m a r y Groups Count Sum Average Variance Group 1 12 56.53 4.71 0.89 Group 4 13 67.07 5.16 1.86 ANOVA Source of variation SS df MS F P-value F critical Between groups 1.25 1 1.25 0.90 0.35 4.28 Within groups 32.07 23 1.39 Total 33.32 24

PAGE 48

48 Table 3-8. ANOVA test between half-weight new shingle and half -weight old roof shingle for 0.61 m (2 ft) x 0.61 m (2 ft) 3.18 mm (1/8 in) glass S u m m a r y Groups Count Sum Average Variance Group 3 15 58.53 3.90 0.79 Group 5 7 25.64 3.66 0.65 ANOVA Source of variation SS Df MS F P-value F critical Between groups 0.27 1 0.27 0.36 0.55 4.35 Within groups 15 20 0.75 Total 15.27 21 Table 3-9. ANOVA test between full-weight old roof shingle a nd half-weight old roof shingle for 0.61 m (2 ft) x 0.61 m (2 ft) 3.18 mm (1/8 in) glass S u m m a r y Groups Count Sum Average Variance Group 4 13 67.07 5.16 1.86 Group 5 7 25.64 3.66 0.65 ANOVA Source of variation SS df MS F P-value F critical Between groups 10.18 1 10.19 6.99 0.016 4.41 Within groups 26.24 18 1.46 Total 36.43 19 Table 3-10. ANOVA test between Au torotation mode and Tumbling mo de of flight for 0.61 m (2 ft) x 0.61 m (2 ft) 3.18 mm (1/8 in) gl ass impact by new full-weight shingle S u m m a r y Groups Count Sum Average Variance Group 1 12 56.53 4.71 1.89 Group 7 6 25.88 4.31 0.36 ANOVA Source of variation SS df MS F P-value F critical Between groups 0.63 1 0.63 0.87 0.36 4.49 Within groups 11.58 16 0.72 Total 12.22 17

PAGE 49

49 Table 3-11. Results summary of mean threshold ve locity, momentum, and kinetic energy for glazing testing Group 1 2 3 4 5 6 7 Annealed glass 0.61 m (2 ft) x 0.61 m (2 ft) x 3.18 mm (1/8 in) 0.61 m (2 ft) x 1.22 m (4 ft) x 3.18 mm (1/8 in) 0.61 m (2 ft) x 0.61 m (2 ft) x 3.18 mm (1/8 in) 0.61 m (2 ft) x 0.61 m (2 ft) x 3.18 mm (1/8 in) 0.61 m (2 ft) x 0.61 m (2 ft) x 3.18 mm (1/8 in) 0.61 m (2 ft) x 0.61 m (2 ft) x 4.76 mm (3/16 in) 0.61 m (2 ft) x 0.61 m (2 ft) x 3.18 mm (1/8 in) Shingle type Full weight new Full weight new Half weight new Full weight old Half weight old Full weight new Full weight new Flight mode Autorotation Tumbling Mean breakage velocity (m/s) 11.81 12.17 19.13 13.50 17.97 17.35 10.59 Mean momentum (kg*m/s) 4.71 4.8 3.90 5.15 3.66 6.83 4.31 Mean kinetic energy (kg*m2/sec2) 28.83 30.15 39.11 37.06 34.34 59.85 23.20

PAGE 50

50 A B Figure 3-1. Testing facility. A) Wooden box. B) Glazing support frame.

PAGE 51

51 A B C D Figure 3-2. Shingle missile launche r. A) Full view of launcher. B), C), D) Different units of launcher. Metal frame Tires Shaft Shingle launching plate Motor Metal frame member allows rotation of shingle launching plate

PAGE 52

52 A B C D Figure 3-3 Common glass breakage patterns A) 2x2 1/8 annealed glass (700 RPM). B) 2x2 1/8 annealed glass (800 RPM). C) 2x2 1/8 annealed glass (450 RPM). D) 2x4 1/8 annealed glass (900 RPM). E) 2x4 1/8 annealed glass (750 RPM).

PAGE 53

53 E Figure 3.3 Continued.

PAGE 54

54 CHAPTER 4 IMPACT OF ROOFING TILES AND 2X 4 MI SSILES ON WINDOW SHUTTERS The second objective of the res earch concerned the damage cau sed by tile missile impact on shutters. This chapter presents the experimental configuration and protoc ol used in this study and provides details on apparatuses used. Results of this testing are presented herein, and are compared to identical tests performed as per the standard large missile (2x4) impact test prescribed in FBC 1626.2. 4.1 Experimental Configuration To simulate the effect of roofing tiles im pacting window shutters, a custom projectile launcher and reaction frame were constructed, and a high-speed camera was used to estimate the velocity of the projectile. This section elabor ates on these apparatuses and the experimental procedure. 4.1.1 Reaction Frame and Shutter Mounts A 1.91 m (75 in) wide x 1.52 m (60 in) tall r eaction frame was used to support th e shutter assembly (Figure 4-1). The frame was construc ted using 4x4 wood members. The reaction frame can accommodate 1.45 m (57 in) high window shu tters. The base of th e reaction frame was attached to a concrete strong floor using anc hor bolts to prevent the frame from sliding upon impact. The shutter systems were installed on the reaction frame using commonly used bottom track and top track at the sill and head of the fr ame, respectively. A 5.08 cm (2 in) x 5.08 cm (2 in) studded angle served as the bottom track. The shutters were secured into the studded angle sill track using wing nuts. Two styles of shutte r mountings were employed in this study: The direct mount method and tracking method. For the direct mount method, shutters were secured directly using 6.35 mm (1/4 in) di ameter anchors at the head leve l. In the tracking method, an H-

PAGE 55

55 track was used at the top. Shutters could simp ly slip up into a header channel without any fasteners. 4.1.2 Tile Projectile Launcher In this study, a pneumatic ram accelerated the ti le missiles to achieve a prescribed flight velocity prior to impact on the test specimen. The ram is powered by air stored in a 75.7 liter (20-gallon) 6.9 kN/m2 (130 psi) capacity accumulation tank, and a solenoid-operated Magnetrol 10.16 cm (4 in) ball valve connect s the tank to the ram. The acceleration of the ram is dependent on the size and speed of the valve, which determin es the discharge rate. Accordingly, the valve was selected to achieve a maximum final ve locity of 30.48 m/s (100 fps). The valve was operated by 5 V (TTL) signal supplied from a National Instrument USB-6211 module, driving solid state relay to provide the necessary AC power. Pressure in the accumulation tank is monitored using an Omegadyne PX309-150G5B pressure transducer, which is capable of measuring 0 1 MPa (0150 psi). The pneumatic ram connects to a 100 mm (4 in) schedule 80 PVC tube. The PVC tube is 1.35 m (4.5 ft) long. Inside the tube, a Delrin plas tic disc is attached to an aluminum push rod guided by a hole in the end of the PVC tube (Figure 4-2). A plate is connected to the other end of the push rod, which protrudes from the PVC tube. Two 8020 modular aluminum channels extend from the end of the PVC tube to the full extent of the push rod, and they support a plywood tray covered with a 0.635 mm DuPont Delr in thermoplastic polymer sheet. The air ram is designed to accommodate a wide range of project iles. For the tile specimens, it was necessary to adhere 2700 mm x 230 mm x 0.635 mm Delrin pads on the bottom of the tile to ensure that the tile could slide smoothly on the surface. Multiple safety measures were implemented. Laser diodes ensure the piston that the piston is fully engaged before the tank can be ch arged. A separate purge valve was incorporated

PAGE 56

56 in the design to prevent overch arging the tank. A mechanical overpressure safety valve is also attached to the air tank to prevent over-pressurization of the system. A custom National Instruments Labview 8.5 program coordinated data acquisition and control system (Figure 4-3). A National Instrument Model monitored the system pressure in the accumulation tank and controlled the valves. 4.1.3 The 2x4 Projectile Launcher The large missile air cannon used compresse d air to launch 2x4 large missiles onto window shutters. A large missile cannon consists mainly of the following components: an air compressor, pressure-release valve, pressure gauge, and a barrel and its support frame. A 6.1 m (20 ft) barrel rests on an aluminum beam hanging from steel cables supported by a steel tube frame. The barrel height can be ad justed using a pair of winches. One compressor provides the air pressure required to facili tate the launch of the 2x4 missile. A smaller compressor powers the trigger-release mechanis m. Once the desired la unching pressure is attained, pushing the trig ger activates the piston, which opens the release valve. The stopping bolt is located near the firing controls. The stop assures that each missile will be fired from a consistent distance. 4.1.4 A High-Speed Camera A Vision Research Phantom V5.2 high-speed camera captured color footage of the tile missile projectile in flight to determine the projectile velocity. The camera recorded 1000 fps after it was configured for 1152 x 896 pixel frame resolution. The camera was positioned 1.02 m to the side of the path of the projectile to reco rd a profile view. A 3.05 m (10 ft) long x 0.20 m (8 in) wide board marked with vertical reference li nes at 0.025 m (1 in) inte rvals was located on the opposite side such that the tile passed between the board and the camera. Reference lines were

PAGE 57

57 also marked on tiles to quantify the angular velocity. Appendix G provi des a sample impact velocity calculation. 4.2 Test Materials Window shutters were tested us ing two different missiles. Th e first missile was concrete tile. The second was a 4.1 kg 2x4 as specified in FBC 1626.2. Galvanized steel storm panels with a thickness of 0.76 mm (0.030 in) were used for testing. Shutters were secured using 6.35 mm (1/4 in) 20 threaded wing nuts on the standard 5. 08 cm (2 in) x 5.08 cm (2 in) studded angle at the sill. An H-box was used to secure the top of the shutter (Figure 4.5). It has a 5.08 cm (2 in) wide gap to accommodate the shutter at the t op without mounting hardware. Tapcon storm guard anchors of 6.35 mm ( in) x 57.15 mm (2 in) were used for directly m ounting the shutters. 4.3 Experimental Procedure 4.3.1 Installation of Test Specimen Assembly The first step consisted of installing the botto m track and top track at the sill and head of the reaction frame for the shutters. The studded a ngle was used as a bottom track, and is an Lshaped angle with a stud member. For the top track, two types of installation methods were used. The first design consisted of slid ing shutters into a 5.08 cm (2 in) wide gap of H-track without any mounting hardware including the midspan through bolts at the seams, and the second design consisted of mounting shutters on the reaction fr ame directly with 6.35 mm (1/4 in) diameter Tapcon SG Anchors at the header. Then storm panels were installed in such a way that panels would overlap each other at the ends. The storm panels were secured into the studded angle at sill level using 6.35 mm (1/4 in) diameter wing nuts. 4.3.2 Preparation of Missiles Each tile and 2x4 lumber missile were assi gned a unique identification number, and their weight was measured and recorded.

PAGE 58

58 4.3.3 Missile Impact on Hurricane Shutters After the storm panels were mounted on the reaction frame, the missile firing sequence was initiated. Once the test specimen was impacted, the pressure in the tank was purged. The same procedure was repeated for each test sp ecimen. Window shutters were impacted by tile missiles at approximately 15.2 m/s (34 mph) and 20.12 m/s (45 mph). For comparison, window shutters were also impacted by 2x4 lumber mi ssiles at approximately 15.2 m/s (34 mph) and 20.12 m/s (45 mph). 4.3.4 Data Collection The test date, missile number, type of mi ssile, coordinates of the point of impact, deflection, any penetration or opening, and instal lation type for shutter were recorded for each test. The sample data worksheet is shown in Appendix E. 4.4 Results The test plan was designed primarily to simulate actual conditi ons that common window storm panel systems could experience in a build ing when subjected to windborne debris impact during extreme winds. All window s hutter systems were tested and results are given in Table 4-1 and Table 4-2. The momentum was calculated using Equation 4-1. vm momentum (4-1) Where m = mass of shingle and v = velocity of the tile Using Equation 4-2, the kine tic energy was calculated. 2** 2 1 vm rgy KineticEne (4-2) For each test specimens the values of momentum and kinetic energy are shown in Table 4-3 and Table 4-4.

PAGE 59

59 4.5 Discussion of Results The results are summarized below: Table 4-5 shows the mean deflection values for the shutters when tested at approximately 15.2 m/s (34 mph). The mean deflection of th e shutters is 1.45 tim es higher for a tile missile as compared with a 2x4 missile, when shutters were secured in the H-box at the head. Table 4-5 shows the mean deflection values for the shutters when tested at approximately 15.2 m/s (34 mph). The mean deflection of the s hutters is 1.2 times higher for a tile missile compared with a 2x4 missile, when shutters were secured using direct anchor at the head. The momentum of the tiles was larger than the 2x4s, which may partially account for this difference. An ANOVA test was performed to understand th e relationship between the tile missile and 2x4 missile impact for the H-box assembly. Ta ble 4-6 shows that the F value is small compared to the critical F value, therefor e we can accept the null hypothesis. The results indicate that the difference in deflection be tween the impact of a tile missile and a 2x4 missile for the H-box assembly is insignificant. An ANOVA test was performed to understand th e relationship between the tile missile and 2x4 missile impact for the dire ct mount assembly. Table 4-7 shows that the F value is small compared to the critical F value, th erefore we can accept the null hypothesis. The results indicate that the difference in deflecti on between the impact of a tile missile and a 2x4 missile for the direct mount assembly is insignificant. Some additional observations based on the experiments are as follows: The shutters were tested at 15.2 m/s (34 m ph) under tile missile impact and 2x4 missile impact, for H-box assembly. Shutters can protru de outward at the head er under tile missile impact, which makes them vulnerable to becoming windborne debris. (Figure 4-15 and Figure 4-17). Shutter testing results show that the performance of the shutters at the header is comparatively better when shutte rs were directly mounted to the reaction frame rather than using the H-box without any mounting accessories under the impact of tile missile and 2x4 lumber. (Figure 4-15 and Figure 4-20).

PAGE 60

60 Table 4-1. Missile impact test results for round 1 te sting at approximately 20.12 m/s (45 mph) Test Missile type Missile speed (m/sec) Installation type Damage description Deflection (m) Figure 20.550 H-Box Impact point near the center of shutter 0.216 4.6 A Tile 20.552 H-Box Impact point at seam of shutter 0.191 4.7 20.117 H-Box Impact point at seam of shutter, hole size 2.54 cm (1) 0.162 4.8 20.117 H-Box Impact point near the center of shutter, hole size 2.54 cm (1) 0.187 4.9 B 2x4 lumber 20.117 H-Box Impact point at seam of shutter, hole size 7.62 cm (3) 0.194 4.10 19.617 Direct mount Impact point near the center of shutter 0.146 4.11 C Tile 20.550 Direct mount Impact point at seam of shutter 0.098 4.12 20.117 Direct mount Impact point at seam of shutter 0.156 4.13 D 2x4 lumber 20.117 Direct mount Impact point near the center of shutter, hole size 3.81 cm (1.5) 0.171 4.14 Table 4-2. Missile impact test results for r ound 2 testing at approxima tely 15.2 m/s (34 mph) Test Missile type Missile speed (m/sec) Installation type Damage description Deflection Figure 16.599 H-Box Impact point near the center of shutter 0.140 4.15 E Tile 15.984 H-Box Impact point at seam of shutter, hole size 1.91 cm (0.75) 0.178 4.16 12.944 H-Box Impact point near the center of shutter 0.102 4.17 F 2x4 lumber 15.199 H-Box Impact point at seam of shutter 0.121 4.18 16.599 Direct mount Impact point at seam of shutter 0.203 4.19 G Tile 16.599 Direct mount Impact point near the center of shutter 0.149 4.20 15.199 Direct mount Impact point near the center of shutter 0.165 4.21 H 2x4 lumber 15.199 Direct mount Impact point at seam of shutter 0.124 4.22

PAGE 61

61 Table 4-3. Momentum and kinetic energy for vari ous test specimens at approximately 20.12 m/s (45 mph) Test Missile mass (kg) Tile speed (m/sec) Momentum (Kg.m/sec) Kinetic energy (Joule)(J) 4.140 20.550 85.077 874.166 A 4.615 20.552 94.847 974.653 3.946 20.117 79.382 798.461 4.350 20.117 87.509 880.209 B 4.350 20.117 87.509 880.209 4.575 19.617 89.748 880.291 C 4.235 20.550 87.029 894.226 4.350 20.117 87.509 880.209 D 4.350 20.117 87.509 880.209 Table 4-4. Momentum and kinetic energy for vari ous test specimens at approximately 15.2 m/s (34 mph) Test Missile mass (kg) Tile speed (m/sec) Momentum (Kg.m/sec) Kinetic energy (Joule)(J) 4.460 16.599 74.032 614.425 E 4.515 15.984 72.168 576.765 4.350 12.964 56.393 365.542 F 4.350 15.199 66.116 502.446 4.060 16.599 67.392 559.319 G 4.215 16.599 69.965 580.673 4.350 15.199 66.116 502.446 H 4.350 15.199 66.116 502.446 Table 4-5. Results summary of mean thresh old velocity, momentum, kinetic energy and deflection for window shutters testing Window shutters Tile missile (HBox) Tile missile (Direct mount) 2X4 missile (HBox) 2X4 missile (Direct mount) Mean speed (m/s) 16.3 16.6 14.1 15.2 Mean momentum (kg*m/s) 73.1 68.7 61.3 66.1 Mean kinetic energy (J) 595.6 570.0 434.0 502.5 Mean deflection (m) 0.16 0.18 0.11 0.15

PAGE 62

62 Table 4-6. ANOVA test between tile missile and 2x4 missile using an H-box assembly at 15.2 m/s (34 mph) Summary Groups Count Sum Average Variance Tile 2 0.318 0.159 0.000722 2x4 2 0.223 0.1115 0.00018 ANOVA Source of variation SS df MS F P-value F critical Between groups 0.00225625 1 0.00225625 5 0.154845745 18.51282051 Within groups 0.0009025 2 0.00045125 Total 0.00315875 3 Table 4-7. ANOVA test between t ile missile and 2x4 missile using the direct mount assembly at 15.2 m/s (34 mph) Summary Groups Count Sum Average Variance Tile 2 0.352 0.176 0.001458 2x4 2 0.289 0.1445 0.0008405 ANOVA Source of variation SS df MS F P-value F critical Between groups 0.00099225 1 0.00099225 0.863389167 0.450885251 18.51282051 Within groups 0.0022985 2 0.00114925 Total 0.00329075 3

PAGE 63

63 Figure 4-1. Reaction frame. A Figure 4-2. Tile missile launcher. A) Full view B) View of different units of launcher. Anchor bolts Air accumulation Tank PVC pipe Frame Pressure gauge

PAGE 64

64 B Figure 4-2. Continued Aluminum rod Wooden base (Tile Launching base) End of piston

PAGE 65

65 Figure 4-3. Labview program vi ew for tile missile launcher Figure 4-4. Board marked with refere nce lines spaced at 2.54 cm (1 in) Fire button Purge button Pre-set pressure

PAGE 66

66 A B C Figure 4-5. Types of installation at header and sill level. A) St andard H header. B) Stud angle at bottom track. C) Direct mount at header. Figure 4-6. Tile missile impact test fo r H-box assembly, center shot (Test A-1)

PAGE 67

67 Figure 4-7. Tile missile impact test fo r H-box assembly, seam shot (Test A-2) Figure 4-8. 2X4 lumber missile impact test for H-box assembly, seam shot (Test B-1)

PAGE 68

68 Figure 4-9. 2X4 lumber missile impact test for H-box assembly, center shot (Test B-2) Figure 4-10. 2X4 lumber missile impact test for H-box assemb ly, seam shot (Test B-3)

PAGE 69

69 Figure 4-11. Tile missile impact test for di rect mount assembly, center shot (Test C-1) Figure 4-12. Tile missile impact test for di rect mount assembly, seam shot (Test C-2)

PAGE 70

70 Figure 4-13. 2X4 lumber missile im pact test for direct mount assembly, seam shot (Test D-1) Figure 4-14. 2X4 lumber missile impact test for direct mount assembly, center shot (Test D-2)

PAGE 71

71 Figure 4-15. Tile missile impact test fo r H-box assembly, center shot (Test E-1) Figure 4-16. Tile missile impact test fo r H-box assembly, seam shot (Test E-2)

PAGE 72

72 Figure 4-17. 2X4 lumber missile impact test for H-box assemb ly, center shot (Test F-1) Figure 4-18. 2X4 lumber missile impact test for H-box assemb ly, seam shot (Test F-2)

PAGE 73

73 Figure 4-19. Tile missile impact test for di rect mount assembly, seam shot (Test G-1) Figure 4-20. Tile missile impact test for di rect mount assembly, center shot (Test G-2)

PAGE 74

74 Figure 4-21. 2X4 lumber missile impact test for direct mount assembly, center shot (Test H-1) Figure 4-22. 2X4 lumber missile im pact test for direct mount assembly, seam shot (Test H-2)

PAGE 75

75 CHAPTER 5 CONCLUSIONS AND RECOMMENDATIONS 5.1 Conclusions Based on the findings in Chapters 3 and 4, this chapter presents conclusions and recommendations regarding the impacts of sh ingle missiles on glazing and tile missiles on window shutters. 5.1.1 Impact of Shingle Missiles on Glazing Window glazings of varying th ickness and span were subjected to simulated windborne shingle impacts in order to provi de a statistical quantification of the threshold of damage. Both new and naturally aged shingles were used for testing the glazing. The conclusions from this research are as follows: Two different glass thicknesses we re considered for testing. As glass thickness increases, the momentum required to break the glass also increases. The mean breakage velocity of 4.76 mm (3/16) glass is 1.47 times great er than 3.18 mm (1/8) glass. The mean breakage velocity for Group 1 (2x2 glass full-weight new shingle) and Group 2 (2x4 glass full-weight new shingle) is approximately 12 m/sec. The mean threshold momentum for both size of glass is 4.71 kg* m/sec and 4.8 kg*m/sec, respectively. Based on an ANOVA test, it was found that there was no statistically relevant difference in speed and momentum when comparing 0.61 m (2 ) x 1.22 m (4) to 0. 61 m (2) x 0.61 m (2) 3.18 mm (1/8) glass specimens. It indicates that the momentum threshold is not a function of specimen size for the range of frontal areas tested. For the roof shingle missile, the impact mo mentum causing a breakag e ranged from 2.35 to 7.04 kg*m/sec for the 3.18 mm (1/8) annealed glass specimens. For the roof shingle missile, the impact mo mentum causing a breakag e ranged from 5.96 to 8.27 kg*m/sec for the 4.76 mm (3/16) annealed glass specimens. Full-weight shingles required a mean th reshold momentum of 4.71 kg*m/s and 5.15 kg*m/s for new and old shingles, respectively. Half-weight shingles required a mean threshold momentum of 3.90 kg*m/s and 3.66 kg*m/s for new and old shingles, respectively. Based on mean momentum va lues and ANOVA analysis, these results indicates that new or old sh ingles perform equally well in breaking the glass window, but different weight shingles do not ha ve the same effect on the glass.

PAGE 76

76 For the roof shingle missile the kinetic energy causing breakage ranged from 10 kg*m/sec to 65 kg*m/sec for 3.18 mm (1/8) annealed glass. For the roof shingle missile, the kinetic energy causing br eakage ranged from 45 kg*m/s to 86 kg*m/sec for 4.76 mm (3/ 16) annealed glass. Momentum appears to be the appropriat e benchmark parameter when determining likelihood of glass breakage. Glass specimens of 0.61 m (2 ft) x 0.61 m (2 ft) x 3.18 mm (1/8 in) were tested under Tumbling flight mode with a new full-weight shingle. The mean threshold momentum for Tumbling mode is 4.31 kg*m/s and for Autorotation mode is 4.71 kg*m/s. 5.1.2 Impact of Roofing Tiles a nd 2x4 Missiles on Window Shutters This research project was c onducted to determine informati on concerning the behavior of commonly used storm panels under large missile impact, using roofing tiles and 2x4 lumber. The following conclusions were drawn from the examina tion of tested hurricane storm panels and the results obtained from the collected data. The mean deflection of the shutters is 1.45 times higher for tile missile compared with the 2x4 missile, when shutters were se cured in the H-box at the head. The mean deflection of the shutters is 1.2 tim es higher for the tile missile compared with the 2x4 missile, when shutters were secured using the direct anc hor at the header. The results clearly showed that directly mount ed panels performed we ll compared with the H-box assembly at the header of the shutter. The shutters protrude outward at the header when impacted using a tile missile for H-box assembly at 15.2 m/s (34 mph). (Figure 4-15, 4-17, 4-20). 5.2 Recommendations for Future Research The results of the study about window glazing behavior against impact of shingle missile should be used to improve risk modeling of windborne debris and to improve glazing performance. In the experimental setup, the glazing was supported on two sides only. Additional testing should be conducted with the glazing s upported along its entire perimeter. Additional testing should be conducted on double-pane glass.

PAGE 77

77 In the experimental setup, the glazing was tested against missile impact. Actual windows should be tested further in order to see th e behavior of actual windows against shingle missile impact. From the window glazing breakage characteristics, determine the type and thickness of window glass necessary to withst and the impact of the design missile. The results of the study about window shutter behavior against impact of tile missile should be used to improve risk modeling of windborne debris and to improve shutter performance. In the experimental setup, galvanized steel panels were tested. Mo re testing should be conducted on aluminum shutters. Further te sting should be conducted on different gauge thickness of window shutters. Additional testing should be conducted using different types of tiles.

PAGE 78

78 APPENDIX A SAMPLE DATA WORKSHEET FO R SHI NGLE MISSILE IMPACT Table A-1. Sample data worksheet for glazing tests Test number Shingle number Shingle damage Yes No Motor RPM Glass type Glass damage Yes No Type of glass damage Crack Shatter Shingle impact location Width Height Additional observation

PAGE 79

79 APPENDIX B SHINGLE VELOCITY CALIBRATI ON AND CO-EFFICI ENT OF GRIP The wheel speed is calculated using motor RPM and its graph is given in Figure B-1. Because of the grip between th e tires, the actual flight speed of the shingle is given by multiplying the wheel speed by the coefficient of grip. As mentioned earlier, the shingle velocity is calculated using a high-speed camera. The sa mple calculation for a full-weight new shingle at 600 RPM is given. Parameters: Motor RPM = 600 Wheel speed = 26.773 mph Shingle = Full-weight new shingle Initial time for shingle positi on I as per Figure B-2 A. t1= 15:22:19.736357 Final time for shingle positi on II as per Figure B-2 B. t2= 18.23.22.446019 Difference in distance traveled by shingle between time difference = 3 in The actual distance traveled by shingle mi ssile is different as per Figure B-3. Using all the values, velocity of shingle at 600 RPM was calculated. Velocity of shingle at 600 RPM = (Distan ce traveled) / (Final Time Initial Time) = (4.95in / (0.0129 sec)) = 9.747 m/sec = 21.802 mph Once we have a value for actual shingle speed, we can relate that value with wheel speed at that RPM to get a value for the co-efficient of grip. Coefficient of grip = (velocity of shingle at 600 RPM) / (wheel speed) = 21.802 / (26.773) = 0.81

PAGE 80

80 The same procedure was repeated to calculate act ual shingle speed at each RPM. The coefficient of grip was calculated by comparing the actual shingle speed and wheel speed for each RPM. Its average value is given as coefficient of grip (For Old/New full-weight shingle) = 0.807, and Coefficient of Grip (For Old/New half-weight shingle) = 0.934. Based on the co-efficient values, the corrected speed graph is drawn and can be seen in Figure B-4.

PAGE 81

81 Figure B-1. Wheel speed plot corresponding to motor RPM.

PAGE 82

82 A Figure B-2. Calibration of full we ight new shingle velocity at 600 RPM. A) Typical view of shingle in high speed camera at position I. B) Typical view of shingle in high speed camera at position II. Initial Time Center of mass of shingle (Initial Position)

PAGE 83

83 B Figure B-2 Continued. Center of mass of shingle (Final Position) Final Time

PAGE 84

84 Figure B-3. Corrected distance travel led by shingle missile for 600 RPM Board marked with reference lines at 1 interval Shingle missile path High speed camera 1.65 31 20

PAGE 85

85 Figure B-4. Corrected shingle speed plot corresponding to motor RPM

PAGE 86

86 APPENDIX C GLASS BREAKAGE VELOCITY The glass breakage velo city was calculated using co-efficient of grip values and given in Table C-1. Table C-1. Glass breakage velocity Glass breakage velocity (m/sec) Mode of flight Autorotation Tumbling 1/8 Annealed glass (2x2) 1/8 Annealed glass(2x4) 1/8 Annealed glass(2x2) 1/8 Annealed glass(2x2) 1/8 Annealed glass(2x2) 3/16 Annealed glass(2x2) 1/8 Annealed glass(2x2) Full weight new shingle Full weight new shingle Half weight new shingle Full weight old shingle Half weight old shingle Full weight new shingle Full weight new shingle 7.25 8.85 11.18 8.05 12.11 15.29 8.38 8.85 11.27 11.18 8.05 14.91 16.10 9.08 9.66 12.07 14.91 8.85 15.84 16.10 11.17 11.27 12.07 15.84 11.27 16.77 16.91 11.17 11.27 12.07 15.84 12.88 20.49 16.91 11.87 11.27 12.88 17.70 13.69 22.36 16.91 11.87 12.07 13.69 19.57 13.69 23.29 17.71 12.88 14.49 20.49 13.69 19.32 13.69 21.43 16.10 20.93 13.69 22.36 16.91 14.49 22.36 16.91 15.29 22.36 16.91 23.29 18.51 24.22 24.22

PAGE 87

87 APPENDIX D SHINGLE SIZE REDUCTION The 3-tab sh ingles were cut into three full weight shingles as shown by cut marks (AA) and (BB) in Figure D-1. To make half-weight shi ngles, the procedure below was followed. Average size of one shingle = 30.48 cm (12 in) X 30.48 cm (12 in) Average weight of one shingle = 400 gm Average size/average weight = 2.32 cm2 /gm To make half-weight shingle, the requ ired area of shingle = (2.32*400)/2 = 464 cm2 Size of the half-weight shingle = 21.54 cm (8.5 in) X 21.54 cm (8.5 in) Full-weight shingle was cut as per dotted line shown in Figure D-2 to make a half-weight shingle. Figure D-1. Three-tab shingle. A A B B

PAGE 88

88 Figure D-2 Shingle size reduction. 21.5cm 21.5cm

PAGE 89

89 APPENDIX E SAMPLE DATA WORKSHEET FOR SHUTTER TESTING Table E-1. Sa mple data worksheet for shutter tests Test number Distance to target Pressure (psi) Missile type Missile number Missile weight (kg) Missile dimension Length Width Damage H-Box Wing nuts/Stud W1 W2 W3 W4 W5 W6 W7 W8 W9 Panels P1 P1 P1 P2 P2 P2 P3 P3 P3 P4 P4 P4 Impact Notes Location Horizontal Vertical Additional observations Installation type Type of shot Deflection Number of affected panels

PAGE 90

90 APPENDIX F MEASUREMENT OF MISSILE VELOCITY Pressure in the Tank 30 psi Missile Tile Initial T ime 10:42:29.979646 Final Time 10:42:29.988392 Distance travelled as per referenced line 4 in The actual distance travelled by missile is different due to focal length of the camera. The corrected distance factor can be calculated ba sed on the difference of the length between the actual tile missile path and reference board with respect to camera lens. As per Figure F-1, the corrected distance factor is (1.76 1) = 0.76 in Corrected distance travelled (4*0.7692) + 4 = 7.0768 in Velocity of tile missile = (Corrected distance) / (Final time Initial time) = 7.0768 / (0.008746) = 809.147039 in/sec = 67.42892 ft/sec = 20.55 m/sec As shown above, for each test the corrected distance was calculated a nd the corresponding tile missile velocity was also calculated. The distance travelled by the tile missile was meas ured for each test because of a slight variation in tank pressure. Depending upon the requirement of impact velocity, th e air accumulation tank pressure was adjusted. The coefficient of variation is very small for both pressure values. The 2x4 lumber missile velocity was measured using a radar speed gun.

PAGE 91

91 Table F-1. Cannon pressure Vs tile speed Air tank pressure (Tile launcher) (psi) Corrected measured tile speed (m/sec) Average speed (m/sec) Coefficient of variation (COV) 20.550 20.552 19.617 30 20.550 20.317 2.30 % 16.599 15.984 16.599 21 16.599 16.445 1.87 %

PAGE 92

92 Figure F-1. Corrected distan ce travelled by tile missile Board marked with reference lines at 1 interval Tile missile path High speed camera 1.76 22 17

PAGE 93

93 APPENDIX G ONE WAY ANALYSIS OF VARIANCE (ANOVA) W hen we have a single factor with several le vels and multiple observations at each level, the one-way ANOVA method is useful to compare the mean difference in two or more groups. The steps for a one-way ANOVA test are perfor med and explained with example below. Hypothesis There are no differences among th e different group of means. (H0 1 = 2). The alternate hypothesis states that there are si gnificant differences among them. (H1 1 2). Alpha level =0.05 Example Group X 10,12,14,16 Group Y 14,20,26,30 Group X countx = 4, sum = 52, average = 52/4 = 13, Group Y county = 4, sum = 90, average = 90/4 = 22.5, Sum of square between group (SSB) = (( X)2)/ countx + (( Y)2)/ county (( T)2)/ Total count (SSB) = (52)2/4 + (90)2/4 (142)2/8 (SSB) = 180.5 Degrees of freedom between groups (dfB) = No. of group -1 = 2-1 = 1 Sum of squares within group (SSw) = { X2 [( X)2/ countx ]} + { Y2 [( Y)2/ county ]} (SSw) = (696 676) + (2172 2025) (SSw) = 167 Degrees of freedom within group (dfw) = Total count No. of group = 8-2 = 6 Mean square between group (MSB) = (SSB)/(dfB) = 180.5/1 = 180.5

PAGE 94

94 Mean square between group (MSw) = (SSw)/(dfw) = 167/6 = 27.83 F = (MSB)/ (MSw) = 6.49 The critical value of F at the 0.05 level, 1 degr ee of freedom between the groups and 6 degrees of freedom within group is F0.05 (1, 6) = 5.98 Write the decision rule for re jecting the null hypothesis Reject H0 if F FCritical Write the statement of results based on decision.

PAGE 95

95 REFERENCES AAMA/ WDMA/CSA 101/I.S.2/A 440 Standard specification for windows, doors and unit skylights American Architectural Manufacture Association 1827 Walden office square, Suite 550, Schaumburg, Illinois 60173-4268. AAMA506-05 Voluntary specification for hurricane im pact and cyclic testing of fenestration products American Architectural Manufacture Association 1827 Walden office square, Suite 550, Schaumburg, Illinois 60173-4268. ASCE 7-05 (2006). Minimum design loads for bu ildings and other structures American Society of Civil Engineers, Reston, VA. ASTM E1886-02 Standard Test Method for Perf ormance of Exterior Windows, Curtain Walls, Doors, and Storm Shutters Impacted by Missile(s) and Exposed to Cyclic Pressure Differentials, American Society for Testing and Materials 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA, 19428 ASTM E1996-99 Standard Test Method for Performance of Exterior Windows, Curtain Walls, Doors, and Storm Shutters Impact ed by wind born debris in Hurricane, American Society for Testing and Materials, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA, 19428 ASTM D3462-03 Standard specification for Asphalt Shingles Made from Glass Felt and Surfaced with Mineral Granules, American Society for Testing and Materials 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA, 19428 Ayscue J.K. (1996), Hurricane damage to reside ntial structures: risk and mitigation Retrieved October 20, 2008 from Natural Hazards Resear ch and Applications Information Center http://www.colorado.edu/hazards/publications/wp/wp94/wp94.htm l Beason, W.L. (1974). Breakage Characteristics of Window Gla ss Subjected to Small Missile Impacts, Thesis, Civil Engineering Department, Texas Tech University Beason, W.L., Meyers, G.E., and James, R.W. (1984), Hurricane relate d window glass damage in Houston, Journal of Structural Engineering Vol110, Issue 12, 2843-2857 Bole, S.A. (1999). Investigations of the M echanics of Windborne Missile Impact on Window Glass, Thesis, Civil Engineering De partment, Texas Tech University Braden C.P. (2004). Large wind missile impact performance of public and commercial building assemblies, Thesis, Civil and Coastal Engineer ing Department, University of Florida. Cook N.J. (1985). The designers guide to wind load ing of building structuresPart 2, Building Research Establishment.

PAGE 96

96 Federal Emergency Management Agency (FEM A). (2005a). Mitigation Assessment Team Report: Hurricane Charley in Florida, Rep No FEMA 488, 5.1-5.68, Washington, D.C. Federal Emergency Management Agency (F EMA). (2005b). Mitigation Assessment Team Report: Hurricane Ivan in Alabama and Florid a, Rep No. FEMA 489, 5.1-5.65, Washington, D.C. Federal Emergency Management Agency (FEMA). (2000). Design and C onstruction guidance for Community Shelters, Rep No. FEMA 361, 1-122, Washington, D.C. Federal Emergency Management Agency (FEMA). (2000). Hurricane Char ley in Florida, Rep No. FEMA 488,5.1-5.65, Washington, D.C. Federal Emergency Management Agency (F EMA). (2003). HAZUS-MH Technical Manual, Chapter 5, Washington, D.C. Florida Building Code (FBC). (2001). Florida Build ing Code, State of Florida, Tallahassee, FL. Gurley, K. (2006). Post 2004 Hurricane field surv eyAn evaluation of the relative performance of the Standard building code and the Florida bu ilding code, University of Florida, 32611. Gurley, K. (2008). Impact of roof shingles on typical residential glass, Un iversity of Florida, 32611. Harris, P.L. (1978). The Effects of Thickness and Temper on the Resistance of Glass to Small Missile Impact, Thesis, Civil Engineer ing Department, Texas Tech University Hattis, D.B. (2006). Standards Governing Glazing Design in Hurricane Regions, Journal of Architectural Engineering, 12(3), 108-115. Holmes, J. D. (2002). Wind Loading of Structures, Spon Press, New York, NY. International Code Council (ICC) (2006). International Residentia l Code, ICC, Falls Church, VA. International Code Council (ICC). (2005). I CC/NSSA Draft on Standard on the Design and Construction of Storm Shelters, Falls Church, VA. Krishna P. (1995). Wind loads on low rise buildings A review, Journal of Wind Engineering and Industrial Aerodynamics Vol54-55, 383-396. Lin N. Holmes, J.D., and Letchford, C.W. (20 07). Trajectories of Wind-borne debris in horizontal winds and applications to impact testing, Journal of Structural Engineering, Vol 133, Issue 2, 274-282.

PAGE 97

97 Meloy, Nick, Sen, Rajan, Pai, Niranjan, and Mu llins, Gray, (2007). Roof damage in new homes caused by Hurricane Charley, Journal of Structur al Engineering, Vol21, Issue 2, 97-107. Minor, J. (1994). Windborne de bris and building envelope. J. Wind. Eng. Ind. Aerodyn ., 53(12), 207-227. Minor J.E. (2005), Lessons learned from failu res of the building envelope in Windstorms, Journal of Architectural Engineering Vol 11, Issue 1, 10-13. National Hurricane Center, www.nhc.noaa.gov, last updated August 2007. NAHB Research Center (2002), W indBorne Debris Impact Resi stant of Residential Glazing, report prepared for the U.S. Department of Housing and Urban Development, Upper Marlboro, MD. Oliver, Clifford, and Hanson, Chris (1994), Failure of Residential building envelopes as a result of hurricane Andrew in Dade County, Florid a, Hurricanes of 1992, Ed. Ronald A Cook, Mehrdad Soltani, New York, NY, 496-508. Pielke, R.A., and Landsea, C.W.(1998), Normaliz ed hurricane damages in the United States: 1925, Weather and Forecasting Vol13, 621. Reinhold Timothy, (2005), Assessing the performance of Modern building codes and Standards in reducing Hurricane Damage, Retrieved July 26, 2008 from http://www.myfloridacfo.com/hurricaneinsuran cetaskforce/TaskforceRS2/Appendix2/9eHurrica neInsuranceMeeting12-14-05.pdf Southern Building Code Congress Internationa l (SBCCI), (1994). SBCCI Test Standard For Determ ining Impact Resistance From Wi ndborne Debris, SSTD 12-94, SBCCI, Inc., Birmingham, Alabama. Stormshutters.com. Head and Sill profiles of storm panels, Retrieved December 1, 2008 from http://www.stormshutters.com/storm-panels/profiles.html. TAS 201-94, Im pact Test Procedur es, Florida Building Code Test Protocols for High-Velocity Hurricane Zones, Department of Community Affairs Building Codes and Standards, 2555 Shumard Oak Boulevard, Ta llahassee, Florida, 32399. Unanwa, C.O., and McDonald, J.R. (2000), Stati stical analysis of Tornado generated wood missiles, 8th ASCE Speciality Conference on Probabilist ic Mechanics and Structural reliability July 22-26, 2000, University of Notre Dame, Indiana, USA.

PAGE 98

98 Wills, J. A. B., Lee, B. E., and Wyatt, T. A. (2002). A model of wi ndborne debris damage. J. Wind. Eng. Ind. Aerodyn ., 90(4), 555. Yeatts B.B. and Mehta K.C. (1993), F ield study of internal pressures, Proceedings of 7th United States National Wi nd Engineering Conference June 27-30, 1993, University of California, Los Angles, USA, 889-897.

PAGE 99

99 BIOGRAPHICAL SKETCH Nirav Sunil Shah was born in Ahmedabad, India in 1985. He attended high school at Sheth C.N. Vidyalaya, Ahmedabad, India. He began his undergraduate studies at L.D. College of Engineering (Ahmedabad, Gujarat, India) in 2002. He graduated in June 2006 with his Bachelor of Engineering degree in ci vil engineering with dis tinction. After that he moved to the University of Florida at Gainesville, Florida to complete his masters degree in civil engineering with specialization in struct ural engineering.