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Evaluation of Disconnect Boxes and Signal Heads for Improved Hurricane Resistance

Permanent Link: http://ufdc.ufl.edu/UFE0045593/00001

Material Information

Title: Evaluation of Disconnect Boxes and Signal Heads for Improved Hurricane Resistance
Physical Description: 1 online resource (87 p.)
Language: english
Creator: Moon, Jaclyn E
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2013

Subjects

Subjects / Keywords: disconnect -- signal -- standard -- test -- traffic -- wind
Civil and Coastal Engineering -- Dissertations, Academic -- UF
Genre: Civil Engineering thesis, M.E.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: The performance of span wire traffic signal systems during hurricanes has demonstrated a need to improve the hurricane resistance of disconnect boxes and signal heads. Damage to span wire signals during hurricanes was observed to occur in the hanger, top of the disconnect box, or the disconnect box-signal connection. The failures suggest a need for standardized load criteria and product testing methods for disconnect boxes and signal heads. The project objectives were to quantify breaking strength requirements for disconnect boxes and signal heads and to develop test methods for product testing. Flexure and tension test programs were developed with the goal of creating repeatable test procedures. A total of 84 tests were performed, 42 in tension and 42 in flexure, and the failure load was recorded for each. The tests performed include both flexure and tension test series for each of five disconnect boxes, four signal heads, and a combined signal-disconnect system. Additional tests using retrofit reinforcement were performed on a representative large disconnect box, small disconnect box, signal head, and combined disconnect-signal system. Results from testing show: · Signal heads and disconnect boxes have a similar range of breaking strengths when compared in flexure and compared in tension · Disconnect boxes most commonly fail in the corners, followed by adapter hub failure; signal heads most commonly fail at the top connection · Results did not strongly indicate significant improvement provided by the reinforcement tested · Combination tests of disconnect boxes and signals failed at the location and load of the worst performing component in that system The study provided data for determining load criteria for signal and disconnect box qualification. The ability of products to resist hurricane loads can be improved by requiring a higher breaking strength of components than the strength exhibited during testing. Improvements can be achieved by considering the failure modes seen during testing and improving the weakest locations in the system. Locations shown to be weak during testing include the corners of disconnect boxes, adapter hubs, the top connection of disconnect boxes, and the top of signal heads. The study also provided methods for product testing in both flexure and tension. The implementation of the result of this test program will result in a standardized evaluation of product performance, as well as ultimately improve the performance of span wire traffic signal systems during hurricane events. Recommendations are provided regarding qualification requirements for improved hurricane resistance.
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 Jaclyn E Moon.
Thesis: Thesis (M.E.)--University of Florida, 2013.
Local: Adviser: Cook, Ronald Alan.

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2013
System ID: UFE0045593:00001

Permanent Link: http://ufdc.ufl.edu/UFE0045593/00001

Material Information

Title: Evaluation of Disconnect Boxes and Signal Heads for Improved Hurricane Resistance
Physical Description: 1 online resource (87 p.)
Language: english
Creator: Moon, Jaclyn E
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2013

Subjects

Subjects / Keywords: disconnect -- signal -- standard -- test -- traffic -- wind
Civil and Coastal Engineering -- Dissertations, Academic -- UF
Genre: Civil Engineering thesis, M.E.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: The performance of span wire traffic signal systems during hurricanes has demonstrated a need to improve the hurricane resistance of disconnect boxes and signal heads. Damage to span wire signals during hurricanes was observed to occur in the hanger, top of the disconnect box, or the disconnect box-signal connection. The failures suggest a need for standardized load criteria and product testing methods for disconnect boxes and signal heads. The project objectives were to quantify breaking strength requirements for disconnect boxes and signal heads and to develop test methods for product testing. Flexure and tension test programs were developed with the goal of creating repeatable test procedures. A total of 84 tests were performed, 42 in tension and 42 in flexure, and the failure load was recorded for each. The tests performed include both flexure and tension test series for each of five disconnect boxes, four signal heads, and a combined signal-disconnect system. Additional tests using retrofit reinforcement were performed on a representative large disconnect box, small disconnect box, signal head, and combined disconnect-signal system. Results from testing show: · Signal heads and disconnect boxes have a similar range of breaking strengths when compared in flexure and compared in tension · Disconnect boxes most commonly fail in the corners, followed by adapter hub failure; signal heads most commonly fail at the top connection · Results did not strongly indicate significant improvement provided by the reinforcement tested · Combination tests of disconnect boxes and signals failed at the location and load of the worst performing component in that system The study provided data for determining load criteria for signal and disconnect box qualification. The ability of products to resist hurricane loads can be improved by requiring a higher breaking strength of components than the strength exhibited during testing. Improvements can be achieved by considering the failure modes seen during testing and improving the weakest locations in the system. Locations shown to be weak during testing include the corners of disconnect boxes, adapter hubs, the top connection of disconnect boxes, and the top of signal heads. The study also provided methods for product testing in both flexure and tension. The implementation of the result of this test program will result in a standardized evaluation of product performance, as well as ultimately improve the performance of span wire traffic signal systems during hurricane events. Recommendations are provided regarding qualification requirements for improved hurricane resistance.
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 Jaclyn E Moon.
Thesis: Thesis (M.E.)--University of Florida, 2013.
Local: Adviser: Cook, Ronald Alan.

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2013
System ID: UFE0045593:00001


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1 EVALUATION OF DISCONNECT BOXES AND SIGNAL HEADS FOR IMPROVED HURRICANE RESISTANCE By JACLYN E. MOON A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF ENGINEERING UNIVERSITY OF FLORIDA 2013

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2 2013 Jaclyn E. Moon

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3 To my parents and sister

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4 ACKNOWLEDGEMENTS I would first like to thank my advisor, Ronald Cook for his gracious support and guidance. I would also like to thank Dr. Mast ers for serving on my committee. Several people contributed to the success of testing. I appreciate Dr. Ferraro for his assistance and advice throughout testing. I also appreciate the help of Jordan Nelson who was integral in setting up instrumentation an d advising on test methods. I would especially like to acknowledge L. David Delk for his assistance during testing. He was an extremely dedicated and capable assistant and I am grateful for the commitment he showed to this project. I would also like to tha nk the peers that I came to k now and value for their friendship and advice Finally I would like to thank my family for their emotional, financial, and at times academic support throughout my college career. My mother, father, and sister provide the enc ouragement that inspires me to know and reach my potential

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5 TABLE OF CONTENTS P age ACKNOWLEDGEMENTS ................................ ................................ .............................. 4 LIS T OF TABLES ................................ ................................ ................................ ........... 7 LIST OF FIGURES ................................ ................................ ................................ ........ 8 ABSTRACT ................................ ................................ ................................ .................. 15 CHAPTER ................................ ................................ ................................ ................... 17 1 INTRODUCTION ................................ ................................ ............................... 17 Background ................................ ................................ ................................ ....... 17 Objectives ................................ ................................ ................................ ......... 19 2 LITERATURE REVIEW ................................ ................................ ..................... 20 3 METHODOLOGY ................................ ................................ .............................. 23 Test Matrix ................................ ................................ ................................ ........ 23 Experimental Design ................................ ................................ ......................... 24 Flexure Test Design ................................ ................................ .................. 24 Tension Test Design ................................ ................................ ................. 27 Reinforced Connections ................................ ................................ ............ 29 Instrumentation ................................ ................................ ................................ 30 Flexure Instrumentation ................................ ................................ ............. 30 Tension Instrumentation ................................ ................................ ............ 32 Test Procedures ................................ ................................ ................................ 32 Flexure Procedures ................................ ................................ ................... 32 Tension Procedures ................................ ................................ .................. 33 4 TEST RESULTS AND OBSERVATIONS ................................ .......................... 35 Non reinforced Component Tests ................................ ................................ ...... 35 Test Results ................................ ................................ .............................. 35 Test Observations ................................ ................................ ..................... 38 Reinforced Component Tests ................................ ................................ ............ 38 Test Results ................................ ................................ .............................. 39 Test Observations ................................ ................................ ..................... 41 Non reinforced and Reinforced Combination Tests ................................ ........... 43 Test Results ................................ ................................ .............................. 44 Test Observations ................................ ................................ ..................... 45 Summary of Test Results and O bservations ................................ ...................... 47 5 RECOMMENDATIONS ................................ ................................ ..................... 50 Advantages and Disadvantages of Testing Options ................................ .......... 50 Flexure ................................ ................................ ................................ ...... 50 Tension ................................ ................................ ................................ ..... 50

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6 Ratio of Tension to Flexure ................................ ................................ ....... 51 Testing Recommendations ................................ ................................ ................ 52 AASHTO Wind Load Determination ................................ ........................... 52 Suggestions on Possible Improvements ................................ ............................ 54 Summary of Recommendations ................................ ................................ ........ 54 APPENDIX ................................ ................................ ................................ ................... 56 A TEST RESULTS AND FAILURE MODES FOR EACH TEST ............................ 56 B LIST OF PARTS USED ................................ ................................ ..................... 84 LIST OF REFERENCES ................................ ................................ .............................. 86 BIOGRAPHICAL SKETCH ................................ ................................ ........................... 87

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7 LIST OF TABLES Table Page 1 1 Traffic signal statistics for 2004 hurricane season ................................ ............. 18 3 1 Test m atrix ................................ ................................ ................................ ........ 23 4 1 Average maximum load of components, flexure ................................ ................ 35 4 2 Average maximum load of components, tension ................................ ............... 37 4 3 Product IDs for reinforced testing ................................ ................................ ...... 39 4 4 Average maximum load of reinforced components, flexure ............................... 40 4 5 Average maximum load of reinforced components, tension ............................... 40 4 6 Reinforced to non reinforced ratio of maximum load ................................ ......... 41 4 7 Average maximum load of combinations, flexure ................................ .............. 44 4 8 Average maximum load of combinations, tension ................................ .............. 45 5 1 Ratio of maximum tens ion load to maximum flexure load ................................ .. 51

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8 LIST OF FIGURES Figure Page 1 1 Terminology ................................ ................................ ................................ ..... 19 2 1 Failure of signals supported by dual cables during hurricanes ......................... 20 2 2 Disconnect box and signal assembly specification ................................ ........... 22 3 1 Original test frame ................................ ................................ ............................ 24 3 2 Pipe hanger connection ................................ ................................ ................... 25 3 3 Actuator mounting system ................................ ................................ ................ 26 3 4 Test configuration of each component, flexure ................................ ................. 27 3 5 ................................ ................................ .............. 28 3 6 Test configura tion of each component, tension ................................ ................ 29 3 7 Reinforcement configuration ................................ ................................ ............ 29 3 8 Use of washers in reinforced disconnect and signal head testing ..................... 30 3 9 Load cell mount ................................ ................................ ............................... 31 3 10 String pot mount ................................ ................................ ............................... 31 4 1 Disc onnect box failure modes, flexure ................................ .............................. 36 4 2 Signal head failure modes, flexure ................................ ................................ ... 36 4 3 Disconnect box failure modes, tension ................................ ............................. 37 4 4 Signal head failure modes, tension ................................ ................................ .. 38 4 5 Reinforced disconnect box failure mode, flexure ................................ .............. 40 4 6 Reinforced signal failure mode, flexure ................................ ............................ 40 4 7 Reinforced disconnect box failure modes, tension ................................ ........... 41 4 8 Reinforced signal failure mode, tension ................................ ........................... 41

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9 4 9 Comparison of reinforced to non reinforced results, flexure ............................. 42 4 10 Comparison of reinforced to non reinforced results ................................ .......... 43 4 11 Combination failure modes, flexure ................................ ................................ .. 44 4 12 Reinforced combination failure mode, flexu re ................................ .................. 44 4 13 Combination failure mode, tension ................................ ................................ ... 45 4 14 Reinforced combination failure mode, tension ................................ .................. 45 4 15 Non reinforced component results, flexure ................................ ....................... 48 4 16 Non reinforced component results, tension ................................ ...................... 49 A 1 Test series 1: DS1 in flexure ................................ ................................ ............ 56 A 2 DS1.1 failure mode, crack in bottom corner ................................ ..................... 56 A 3 D S1.2 failure mode, crack in bottom corner ................................ ..................... 56 A 4 DS1.3 failure mode, crack in bottom corner ................................ ..................... 56 A 5 Test series 2: DS2 in flexure ................................ ................................ ............ 57 A 6 DS2.1 failure mode, adapter hub failure ................................ ........................... 57 A 7 DS2.2 failure mode, adapter hub failure ................................ ........................... 57 A 8 DS2.3 failure mode, crack in top corner ................................ ........................... 57 A 9 Test series 3: DL1 in flexure ................................ ................................ ............ 58 A 10 DL1.1 failure mode, crack in bottom corner ................................ ..................... 58 A 11 DL1.2 failure mode, crack in top corner ................................ ........................... 58 A 12 DL1.3 failure mode, crack in top c orner ................................ ............................ 58 A 13 Test series 4: DL2 in flexure ................................ ................................ ............ 59 A 14 DL2.1 failure mode, attachment hardware ................................ ....................... 59 A 15 DL2.2 failure mode, attachment hardware ................................ ....................... 59

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10 A 16 DL2.3 failure mode, attachment hardware ................................ ....................... 59 A 17 Test series 5: DL3 in flexure ................................ ................................ ............ 60 A 18 DL3.1 failure mode, crack at top connection ................................ .................... 60 A 19 DL3.2 failure mode, crack in top c orner ................................ ............................ 60 A 20 DL3.3 failure mode, crack in top corner ................................ ............................ 60 A 21 Test series 6: SH1 in flexure ................................ ................................ ............ 61 A 22 SH1.1 failure mode, crack at top connection ................................ .................... 61 A 23 SH1.2 failure mode, crack at top connection ................................ .................... 61 A 24 SH1.3 failure mode, crack at top connection ................................ .................... 61 A 25 Test series 7: SH2 in flexure ................................ ................................ ............ 62 A 26 SH2.1 failure mode, crack at top connection ................................ .................... 62 A 27 SH2.2 failure mode, crack at top ................................ ................................ ...... 62 A 28 SH2.3 failure mode, break off around top surface ................................ ............ 62 A 29 Test series 8: SH3 in flexure ................................ ................................ ............ 63 A 30 SH3.1 failure mode, crack at top connection ................................ .................... 63 A 31 SH3.2 failure mode, crack at top connection ................................ .................... 63 A 32 SH3.3 failure mode, crack at top connection ................................ .................... 63 A 33 Te st series 9: SH4 in flexure ................................ ................................ ............ 64 A 34 SH4.1 failure mode, crack at top connection ................................ .................... 64 A 35 SH4.2 failure mode, crack at top connect ion ................................ .................... 64 A 36 SH4.3 failure mode, crack at top connection ................................ .................... 64 A 37 Test series 10: C1 in flexure ................................ ................................ ............ 65 A 38 C1.1 failure mode, crack at top of disconnect ................................ ................... 65

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11 A 39 C1.2 failure mode, crack around top of disconnect ................................ .......... 65 A 40 C1.3 failure mode, crack at top of signal ................................ .......................... 65 A 41 Test series 11: RDS1 in flexure ................................ ................................ ........ 66 A 42 RDS1.1 failure m ode, crack in top corner ................................ ......................... 66 A 43 RDS1.2 failure mode, crack in top corner ................................ ......................... 66 A 44 RDS1.3 failure mode, crack in top corner ................................ ......................... 66 A 45 Test series 12: RDL1 in flexure ................................ ................................ ........ 67 A 46 RDL1.1 failure mode, crack starting in top corner ................................ ............. 67 A 47 RDL1.2 failure mode, crack starting in top corner ................................ ............. 67 A 48 RDL1.3 failure mode, crack starting in top corner ................................ ............. 67 A 49 Test series 13: RSH1 in flexure ................................ ................................ ........ 68 A 50 RSH1.1 failure mode, punching at top connection ................................ ............ 68 A 51 RSH1.2 failure mode, cracking in top connection ................................ ............. 68 A 52 RSH1.3 failure mode, cracking in top connection ................................ ............. 68 A 53 Test series 14: RC1 in flexure ................................ ................................ .......... 69 A 54 RC1.1 failure mode, crack around top ................................ .............................. 69 A 55 RC1.2 failure mode, crack around top reinforcement ................................ ....... 69 A 56 RC1.3 failure mode, crack around top reinforcement ................................ ....... 69 A 57 Test series 15: DS1 in tension ................................ ................................ ......... 70 A 58 DS1.1 failure mode, crack around bottom ................................ ........................ 70 A 59 DS1.2 failure mode, crack around bottom ................................ ........................ 70 A 60 DS1.3 failure mode, crack around bottom ................................ ........................ 70 A 61 Test series 16: DS2 in tension ................................ ................................ ......... 71

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12 A 62 DS2.1 failure mode, crack in top corner ................................ ........................... 71 A 63 DS2.2 failure mode, crack at top connection ................................ .................... 71 A 64 DS2.3 failure mode, crack at top corner ................................ ........................... 71 A 65 Test series 17: DL1 in tension ................................ ................................ .......... 72 A 66 DL1.1 failure mode, adapter hub, crack around bottom ................................ .... 72 A 67 DL1.2 failure mode, crack in bottom corner ................................ ...................... 72 A 68 DL1.3 failure mode, crack in bottom corner ................................ ...................... 72 A 69 Test series 18: D L2 in tension ................................ ................................ .......... 73 A 70 DL2.1 failure mode, crack in top corner ................................ ............................ 73 A 71 DL2.2 failure mode, adapter hub failure ................................ ........................... 73 A 72 DL2.3 failure mode, adapter hub failure ................................ ........................... 73 A 73 Test series 19: DL3 in tension ................................ ................................ .......... 74 A 74 DL3.1 failure mode, crack at top connection ................................ .................... 74 A 75 DL3.2 failure mode, crack at top connection ................................ .................... 74 A 76 DL3.3 failu re mode, crack at top connection ................................ .................... 74 A 77 Test series 20: SH1 in tension ................................ ................................ ......... 75 A 78 SH1.1 failure mode, crack at top connection ................................ .................... 75 A 79 SH1.2 failure mode, crack around top surface ................................ ................. 75 A 80 SH1.3 failure mode, crack at top connection ................................ .................... 75 A 81 Test series 21: SH2 in tension ................................ ................................ ......... 76 A 82 SH2.1 failure mode, crack around back of signal ................................ ............. 76 A 83 SH2.2 failure mode, crack at top connection ................................ .................... 76 A 84 SH2.3 failure mode, crack at top of connection ................................ ................ 76

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13 A 85 Test seri es 22: SH3 in tension ................................ ................................ ......... 77 A 86 SH3.1 failure mode, crack at top connection ................................ .................... 77 A 87 SH3.2 failure mode, crack at top connection ................................ .................... 77 A 88 SH3.3 failure mode, crack around top surface ................................ ................. 77 A 89 Test series 23: SH4 in tension ................................ ................................ ......... 78 A 90 SH4.1 failure mode, crack around top surface ................................ ................. 78 A 91 SH4.2 failure mode, crack around top surface ................................ ................. 78 A 92 SH4.3 failure mode, crack around top corner ................................ ................... 78 A 93 Test series 24: C1 in tension ................................ ................................ ............ 79 A 94 C1.1 failure mode, crack a t top of signal ................................ .......................... 79 A 95 C1.2 failure mode, crack at top of signal ................................ .......................... 79 A 96 C1.3 failure mode, crack at top of signal ................................ .......................... 79 A 97 Test series 25: RDS1 in tension ................................ ................................ ....... 80 A 98 RDS1.1 failure mode, crack in top corner ................................ ......................... 80 A 99 RDS1.2 failure mode, crack in top corner ................................ ......................... 80 A 100 RDS1.3 failure mode, crack in top corners ................................ ....................... 80 A 101 Test s eries 26: RDL1 in tension ................................ ................................ ....... 81 A 102 RDL1.1 failure mode, crack around top reinforcement ................................ ..... 81 A 103 RDL1.2 failure mode, crack aroun d top reinforcement ................................ ..... 81 A 104 RDL1.3 failure mode, crack around top reinforcement ................................ ..... 81 A 105 Test series 27: RSH1 in tension ................................ ................................ ....... 82 A 106 RSH1.1 failure mode, crack in top of signal ................................ ...................... 82 A 107 RSH1.2 failure mode, crack in top of signal ................................ ...................... 82

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14 A 108 RSH1.3 failure mode, crack in top of signal ................................ ...................... 82 A 109 Test series 28: RC1 in tension ................................ ................................ ......... 83 A 110 RC1.1 failure mode, crack in top of signal ................................ ........................ 83 A 111 RC1.2 failure mode, crack in top of signal ................................ ........................ 83 A 112 RC1.3 failure mode, cracking in signal ................................ ............................. 83 B 1 Signal head ................................ ................................ ................................ ...... 84 B 2 Disconnect box ................................ ................................ ................................ 84 B 3 Tri stud adapter with attachment hardware ................................ ...................... 84 B 4 ................................ ................................ ................................ 84 B 5 ................................ ................................ ................................ 8 4 B 6 Tri stud to pipe adapter for bottom of disconnect box ................................ ....... 84 B 7 ................................ ................................ .......... 84 B 8 ................................ ................................ ................... 84 B 9 ................................ ................................ ..................... 85 B 10 Top disconnect reinforcement ................................ ................................ .......... 85 B 11 Large disconnect reinforcement, bottom ................................ .......................... 85 B 12 Small disconnect reinforcement, bottom ................................ .......................... 85 B 13 Signal reinforcement ................................ ................................ ........................ 85 B 14 Reinforcement attachment hardware ................................ ............................... 85 B 15 Steel washer for reinforcement connection s ................................ ..................... 85

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15 A bstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Engineering EVALUATION OF DISCONNECT BOXES AND SIGNAL HEADS FOR IMPROVED HURRICANE RESISTANCE By Jaclyn E. Moon May 2013 Chair: Ronald A. Cook Major: Civil Engineering The performance of span wire traffic signal systems during hurricanes has demonstrated a need to improve the hurricane resistance of disconnect boxe s and signal heads. Damage to span wire signals during hurricanes was observed to occur in the hanger, top of the disconnect box, or the disconnect box signal connection. The failures suggest a need for standardized load criteria and product testing method s for disconnect boxes and signal heads. The project objectives were to quantify breaking strength requirements for disconnect boxes and signal heads and to develop test methods for product testing. Flexure and tension test programs were developed with the goal of creating repeatable test procedures. A total of 84 tests were performed, 42 in tension and 42 in flexure, and the failure load was recorded for each. The tests performed include both flexure and tension test series for each of five disconnect box es, four signal heads, and a combined signal disconnect system. Additional tests using retrofit reinforcement were performed on a representative large disconnect box, small disconnect box, signal head, and combined disconnect signal system. Results from te sting show:

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16 Signal heads and disconnect boxes have a similar range of breaking strengths when compared in flexure and compared in tension Disconnect boxes most commonly fail in the corners, followed by adapter hub failure; signal heads most commonly fail at the top connection Results did not strongly indicate significant improvement provided by the reinforcement tested Combination tests of disconnect boxes and signals failed at the location and load of the worst performing component in that system The s tudy provided data for determining load criteria for signal and disconnect box qualification. The ability of products to resist hurricane loads can be improved by requiring a higher breaking strength of components than the strength exhibited during testing Improvements can be achieved by considering the failure modes seen during testing and improving the weakest locations in the system. Locations shown to be weak during testing include the corners of disconnect boxes, adapter hubs, the top connection of di sconnect boxes, and the top of signal heads. The study also provided methods for product testing in both flexure and tension. The implementation of the result of this test program will result in a standardized evaluation of product performance, as well as ultimately improve the performance of span wire traffic signal systems during hurricane events. Recommendations are provided regarding qualification requirements for improved hurricane resistance.

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17 CHAPTER 1 INTRODUCTION 1.1 Background The damage to wire span traffic signal support systems as a result of high wind events has indicated a need for improvement in the connections associated with disconnect boxes. The damage to cable supported traffic signals during Hurricane Andrew in 1992 spurred investigation int o the cause of failure and evaluation of improvements. In 1994 a project funded by FDOT and conducted by Hoit et al. developed the Analysis of Traffic Lights and Signals (ATLAS) computer software for use in analysis and design of traffic signals (as cited in Cook and Johnson, 2007). A study done by the Florida Department of Transportation (FDOT) and the University of Florida (UF) in 1996 developed a test procedure and apparatus to test signals under simulated wind loads (Cook et al., 1996). The damage to tr affic signal support systems during the hurricane season of 2004 suggested that performance of signal systems during hurricanes could still be improved (Florida Department of Transportation [FDOT], 2005). An FDOT report presented the damage observed during the hurricane season, shown in Table 1 1, and was observed in the same report that although mast arms are more effective in withstanding hurricane conditions, span wires can be repaired quickly at low cost compared to mast arms. Of the span wire damage, failure was noted to have occurred in hangers, clamps, and disconnect boxes (Cook et al., 1996). These observations prompted two more studies performed by FDOT and the University of Florida. The first

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18 compared dual wire and single wire support systems by performing full scale wind tests on each (Cook et al., 2007). A subsequent project ev aluated the performance of hangers to determine the best performing hanger for hurricane resistance (Cook et al., 2012). Of the reported span wire system failures during hurricanes, the disconnect box remained to be investigated. Table 1 1 Traffic signal statistics for 2004 hurricane season (FDOT, 2005) District Total no. of signals district wide Total mast arm signals district wide Mast arm structural damage Total span wire signals district wide Signaliz ed intersections that sustained damage 1 1,778 802 2 976 496 2 1,585 537 0 1,048 40 3 987 300 2 687 265 4 3,329 1,180 14 2,149 735 5 2,972 458 2 2,514 1,885 6 2,640 1,848 0 660 0 7 2,151 518 0 1,633 102 Sum 15,442 5,643 20 9,667 3,523 Damage c an be defined as signal loss due to failure of the span wire, bracket assembly, mast arm mounting hardware, or other components. The purpose of a disconnect box is to house wiring and allow easy access for removal of the signal head, either for replacemen t or repair. Disconnect box related failures occur at either the top of the box near the messenger cable attachment or the bottom of the box at the signal head connection (Cook et al., 1996). The purpose of this research was to further investigate failure relating to the disconnect box by evaluating current disconnect box and signal breaking strength using static load tests. This project also considered the effect of available retrofit reinforcement in order to quantify improvements reinforcement provides t o the system. The current FDOT standards do not have a strength qualification or test standards for signal heads and disconnect boxes. Although a test procedure had been previously developed, it was not put into practice due to its use of cyclic loading wh ich

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19 requires additional software and setup. The desire for this test program was to develop static load tests that can be carried out by manufacturers, test labs, or the FDOT. 1.2 Objectives The primary objectives of this project were to quantify load crit eria for disconnect box and signal head products, and to develop a repeatable test program for product testing. A test matrix was developed to perform flexure and tension static tests on each of the disconnect and signal head products on the FDOT approved product list (APL). Additional tests were performed on reinforced components and systems in order to determine the effect of the reinforcement currently available. In addition to developing test procedures and performing tests on currently approved product s, a secondary objective was to develop recommendation for improved hurricane resistance based on test results. Figure 1 1 shows a disconnect box and signal head with relevant terminology which will be used throughout this report. Figure 1 1 Terminology (photo courtesy of author)

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20 CHAPTER 2 LITERATURE REVIEW This project is the latest in a series of research projects funded by FDOT and performed by UF on the topic of wire span traffic support systems. The investiga tion into cable supported traffic signals was spurred by the amount of damage to the systems caused by hurricane Andrew in 1992 ( Figure 2 1 ). Failures observed included damage to hangers and disconnect box connecti ons. Figure 2 1 Failure of signals supported by dual cables during hurricanes (p hoto courtesy of Ronald A. Cook) Each of the previous projects investigated a different aspect of span wire failure observed during high velocity wind events. The first project in the series developed a traffic signal testing program for testing traffic signals and signs and their hardware using cyclic loading to simulate wind loads (Cook et al., 1996). The test frame designed a nd fabricated for the 1996 project was modified for the testing of disconnect boxes and signal heads for the current project. A subsequent research study focused on comparing dual cable and single cable systems with various sag, boxes, weights, and signal orientations in order to determine the forces in the signals, cables, and poles (Cook and Johnson, 2007). The results showed that forces in the cables of single cable

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21 systems do not appreciably increase as wind increases, in contrast to large increases in dual cable tensions. The results determined single cable systems were a better alternative to dual cable systems. The most recent project evaluated each of the dual cable signal support systems using full scale tests with the UF Hurricane Simulator. The te st program compared five hanger systems, measuring signal rotation, cable tensions, the systems that tend to have greater rotation under relatively low wind loads also reduce the increase in cable tension ex The current project is also related to existing standards for traffic signals and devices. Standards related to this project include the Minimum Specifications for Traffic Control Signals and Devices (M STCSD) sections A650 and A659, FDOT Design Standards Index 17727, and ITE Specs Section 3.02. Although materials, assembly, and dimensions are specified, FDOT does not specify load requirements for manufacturers to meet. MSTCSD A650 deals with vehicular t raffic signal assembly, and specifies dimensions and hardware requirements for signals. Any traffic signal loading criteria developed as a result of this project will be published in this section. MSTCSD A659 specifies requirements for signal head auxiliar ies, including disconnect box standards. Disconnect boxes are required to made of aluminum alloy 319.0 having a minimum tensile strength of 23 ksi (FDOT, 2010). Adapter hubs are required to be made of aluminum alloy Almag 35, having a tensile strength of 3 5 ksi (FDOT, 2010). They are secured in the disconnect box to restrict rotational movement and incorporate a hold down device to secure the adapter in place. Disconnect box load requirements that are

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22 developed as a result of this project will be published in MSTCSD A659. The Institute of Transportation Engineers (ITE) Section 3.02 requires signal heads to be able to withstand a sustained wind load of 25 psf applied perpendicular to the front and rear of the signal (ITE 1985). Applying this load over the a rea of a signal and disconnect box, the force requirement comes out to be a sustained load of approximately 110 pounds. FDOT Design Standards Index 17727 shows installation details of cable hanging signals. Disconnect box and signal configurations are sho wn in Figure 2 2 (FDOT 2012). Figure 2 2 Disconnect box and signal assembly specification (FDOT 2012)

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23 CHAPTER 3 METHODOLOGY In order to determine product breakin g strength, static flexure and tension tests were performed on five disconnect boxes, four signal heads, and a comb ined signal disconnect. A lso, tests using retrofit reinforcement were performed on a representative large disconnect box, small disconnect bo x, signal head, and combined system. 3.1 Test Matrix The test program was implemented by developing the test matrix shown in Table 3 1 Table 3 1 Test m atrix Test series no. Reinforced or non reinforced Product Signal component Load direction Replications T1 Non reinforced DS1 Small disconnect Front 3 T2 Non reinforced DS2 Small disconnect Front 3 T3 Non reinforced DL1 Large disconnect Front 3 T4 Non reinforced DL2 Large disconnect Front 3 T5 Non reinforced DL3 Large disconnect Front 3 T6 Non reinforced SH1 Signal head Front 3 T7 Non reinforced SH2 Signal head Front 3 T8 Non reinforced SH3 Signal head Front 3 T9 Non reinforced SH4 Signal head Front 3 T10 Non reinforced C1 Combination Front 3 T11 Reinforced RDS1 Small disconnect Front 3 T12 Reinforced RDL1 Large disconnect Front 3 T13 Reinforced RSH1 Signal head Front 3 T14 Reinforced RC1 Combination Front 3 T15 Non reinforced DS1 Small disconnect T ension 3 T16 Non reinforced DS2 Small disconnect Tension 3 T17 Non reinforced DL1 Large disconnect Tension 3 T18 Non reinforced DL2 Large disconnect Tension 3 T19 Non reinforced DL3 Large disconnect Tension 3 T20 Non reinforced SH1 Signal head Tens ion 3 T21 Non reinforced SH2 Signal head Tension 3 T22 Non reinforced SH3 Signal head Tension 3 T23 Non reinforced SH4 Signal head Tension 3 T24 Non reinforced C1 Combination Tension 3 T25 Reinforced RDS1 Small disconnect Tension 3 T26 Reinforced RDL 1 Large disconnect Tension 3 T27 Reinforced RSH1 Signal head Tension 3 T28 Reinforced RC1 Combination Tension 3

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24 Product IDs have been used for reporting in order to maintain manufacturer result anonymity. DS stands for disconnect small, DL for disconne ct large, SH for signal head, and C for the combination signal and disconnect system. Products used in reinforced test series are preceded with an R for reinforced. In all tests involving signal heads, only the top section of the signal was used, as the to p connection was the point of concern. 3.2 Experimental Design The objective while developing a test method was to design repeatable static load tests for both flexure and tension. 3.2.1 Flexure Test Design Flexure tests made use of a signal testing fra me developed for previous testing at UF in 1996, shown in Figure 3 1 (Cook et al. 1996). The original frame was Figure 3 1 Original test frame (Cook et al ., 1996)

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25 Slight modifications were made to the existing test frame to accommodate this test program. The adaptations consisted of modifications to the hanger sys tem and a the frame in order to simulate a pipe hanger connection as seen in the fie ld. The pipe level and top level. U bolts were used to securely attach the pipe and create a pin connection, shown in Figure 3 2 A B Figure 3 2 Pipe hanger connection A) Overview B) Close up (P hotos courtesy of author) The actuator and mounting method is detailed in Figure 3 3 T he actuator was disconnect box. The location of the actuator takes in to account tha t the test level. The actuator was mounted at the desired location using a ball joint piece attached

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26 ed rod was threaded into the actuator rod on one end and the load cell receiver on the other. The rod was machined down to a 20 thread on the load cell end in order to thread into the load cell button. A mount was fabricated for the load cell to allow de formation of the load cell on one side with a 5 / 8 5 / 8 connected to a clevis piece which was pinned to the ball joint piece attached to a pipe hanging from the bottom of the signal component. Figure 3 3 Actuator mounting system (photo courtesy of author) The configuration of each flexure test changed sligh tly based on which signal compo n ent was being tested. Coupler pieces an d modif ied connections were used for e ac h type of component in order to consistently load samples at the center of area without moving the location of the actuator. Figure 3 4 shows the test configuration of discon nects, signals, and combinations, respectively. Disconnect boxes were tested using a tri stud adapter at the top and a fabricated Load cell mount Actuator Clevis rod end Clevis rod end Ball joint Ball joint

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27 c fabrication piece and has a ball joint conne ction at the location of the center of area. spacer was joined to the frame with a coupler and connected to the signal with a tri stud adapter. A tri stud adapter was us ed at the bottom of each signal as well, allowing a 1 signal. Combinations were tested using a tri stud adapter at both the top of the disconnect box and bottom of the signal head. The same pipe was used at the bottom as was used during signal testing. A B C Figure 3 4 Test configuration of each component, flexure A) Disconnect B) Signal C) Combination (P hotos courtesy of author) 3.2.2 Tension Test Design the University of Florida, shown in Figure 3 5 (Tinius Olsen, 2010). The machine was configured for tension testing by installing manually operated lever type wedge grips

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28 component to fit in the grips of the Tinius Olsen. Figure 3 5 As with flexure testing, each component type required different connections. The setup of each component is shown in Figure 3 6 Tri stud adapters were used at the top of each disconnect to attach the pipe. The fabricated connection used to simulate a signal head was again used for tension at the bottom of each disconnect box. A reducing pipe bushing was used with the fabricated piece d uring tension testing to allow combination testing used tri stud adapters at the top and bottom to connect the pipes. Reinforcement was used at the bottom of the signal during n on reinforced and reinforced combination tests in tension in order to effectively evaluate the signal disconnect interaction. The connections at the top and the bottom of the signal are the same during tension testing, and so in order to isolate the signal disconnect connection, the bottom of the signal to pipe connection was reinforced.

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29 A B C Figure 3 6 Test configuration of each component, tension A) Disconnect B) Signal C) Combination ( P h otos courtesy of author) 3.2.3 Reinforced Connections Reinforced testing was completed similarly to non reinforced testing, the only exception being the addition of reinforcement pieces. Reinforcement is available for the top of large and small disconnect boxes, the bottom of large and small disconnect boxes, and for signal head connections. The reinforcement was designed to enhance the existing connections, fastening over the tri stud connection between signal head and disconnect box. Figure 3 7 shows the reinforcement installed in a disconnect box, signal, and combination, respectively. A B C Figure 3 7 Reinforcement configuration A) Disconnect B) Sig nal C) Combination ( P hotos courtesy of author)

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30 The top disconnect box reinforcement was modified for this testing to be used with tri stud adapters as opposed to a single stud hanger. The bottom disconnect box r bolt through 25 washers, then the fabricated connection, adapter hub, and reinforcement, and secured with a washer and nut. The purpose of the washers was to maintain the proper connection length by modeling the height of signal reinforcement. Signal hea d reinforcement was connected stud adapter to maintain the connection length. A bolt was fastened through the washers, the signal, and the reinforcement and secured by a washer and nut. Figure 3 8 shows the washers in use for reinforced disconnect box and signal head testing, respectively. Combinations were reinforced according to the reinforcement specifications with no modifications required. A B F igure 3 8 Use of washers in reinforced disconnect and signal head testing A) Disconnect box B) Signal head ( P hotos courtesy of author) 3.3 Instrumentation The instruments used during testing included an actuator and pump system, a pancake type load cell, a string potentiometer (string pot), and the Tinius Olsen 400 3.3.1 Flexure Instrumentation The actuator used during testing was a 10 ton capacity hydraulic cylinder with a

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31 a horizontal load on the signal components. The actuator was double acting, with the way valve hand pump was attac hed to the actuator by two hoses to make use of the double action feature of the cylinder. An LCH 5K load cell was mounted to the end of the actuator between the actuator rod and signal component in order to record the force applied during testing. The lo ad cell and mount is shown in Figure 3 9 The load cell measures deformation and converts the deformation into an electric signal which is then recorded as a force reading. The LCH 5K load cell has a 5000 pound cap acity. Figure 3 9 Load cell mount (photo courtesy of author) A string pot was mounted to the frame to acquire displacement data for graphing purposes. It was mounted to the frame next to the actuator wi th the wire end attached to the load cell mount, as shown in Figure 3 10 A B Figure 3 10 String pot mount A) String pot mounted to frame B) Wire end conn ection to load cell mount ( P hotos courtesy of author)

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32 3.3.2 Tension Instrumentation method used to perform tension tests. The Tinius Olsen has a load capacity of 400,000 lbf and a handheld controller and computer with Test Navigator Testing Software. The Navigator software can control load rate, failure definition, and specimen parameters as applicable. Data a re shown in real time on the monitor during testing and stored as a .cvc file upon completion of a test. 3.4 Test Procedures The first step for each test was to set up each component as described in Section 3.1.1, 3.1.2, and 3.1.3 for flexure, tension, and reinforcement as applicable. Once the appropriate configuration has been set up, the test procedures were uniform irrespective of the component being tested. 3.4.1 Flexure Procedures Data acquisition software was initiated to begin the test. Load was th en applied by depressing the handle of the hand pump at a constant rate of 20 seconds for one full depression, quickly raising the handle, and repeating until failure was reached in the specimen. Failure was determined by significant drop off in load accom panied with visible cracking in the specimen. The actuator was returned to its starting position by reversing the valve toggle on the hand pump and pumping the handle. Although flexure tests were performed using a specially designed test frame, the test c an be completed without the use of specialized equipment. All that is required is a hanger system secured with two pin connections above the signal component and

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33 application of a static load at the center of area of the signal until failure. 3.4.2 Tension Procedures The following tension procedure was performed using the Tinius Olsen 400 any similar materials testing machine given the machine has an appropriate capacity a nd height. The test was begun by turning on the pump, then the computer, and loading the test settings. A program was used for signal and disconnect product testing specifying displacement rates and definition of failure. The test was programmed to load t he specimen in two stages. The purpose of the first stage was to fully engage the grips, so an initial load rate of 0.125 in/sec was used from 0 100 lbs. At 100 lbs the load rate was decreased to 0.25 in/min for the remainder of the test. The test was set to run until specimen failure, defined in the program as 70% drop off in load. To begin each test, the crosshead was returned to its home position after turning the pump on and before loading any samples. The mechanical head was lowered to allow room for the test specimen. The specimen was loaded by inserting the top pipe through the top grip and lowering the lever of the grip to clamp the pipe. For a secure grip. Th e bottom lever was at its lowest position, allowing the bottom grips to remain open. The mechanical head was then raised until the bottom pipe slid through the grips and was visible at the bottom of the mechanical head. The bottom lever was then raised to clamp the grips onto the bottom pipe. Both the bottom and top pipes were extending

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34 secure hold. Once the sample was in place, the instrumentation was zeroed and test was in the program automatically ended the test. At that point, the specimen was unloaded by returning the crosshead to its zero position and releasing the grip levers to remove the s pecimen.

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35 CHAPTER 4 TEST RESULTS AND OBSERVATIONS The results of interest during testing were the maximum force and failure mode of each product. Three rep licatio ns of each test series were performed and the average maximum load of the three was reported as the failure load for the series. Raw data and pictures of failures for each test performed are shown in Appendix A. 4.1 Non reinforced Component Tests 4.1.1 Test Results The first stage was to determine the failur e load of each product. Table 4 1 shows flexure test results of each product, reporting the average maximum load and the range of maximum loads for the three tests in each series. The average breaking strength of a ll of the components tested in flexure was 343 lbs with a 26% coefficient of variation. Table 4 1 Average maximum load of components, flexure Test series Product Component Average maximum load (lb) Range of m aximum load (lb) T1 DS1 Small disconnect box 337 319 356 T2 DS2 Small disconnect box 376 358 386 T3 DL1 Large disconnect box 351 333 378 T4 DL2 Large disconnect box 437 310 546 T5 DL3 Large disconnect box 250 207 292 T6 SH1 Signal head 451 421 512 T 7 SH2 Signal head 300 166 462 T8 SH3 Signal head 237 185 282 T9 SH4 Signal head 350 337 364 The failure mode of each test was also documented, and an example of each failure mode is shown. Of the disconnect boxes tested in flexure, five failed in the t op corners, four failed in the bottom corners, three failed in the attachment hardware, two failed in the adapter hub, and one failed from cracking at the top connection. Figure 4 1 shows an example of each of thes e failure modes. Figure 4 2 shows signal head

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36 failures, eleven of which failed by cracking in the top connection during flexure tests, and one of which failed by a break off of the top surface. A B C D E Figure 4 1 Disconnect box failure modes, flexure A) Top corner B) Bottom corner C) Attachment hardware D) Adapter hub E) Top connection (Photos courtesy of author) A B Figure 4 2 Signal head failure modes, flexure A) Top connection. B) Top surface. (P hotos courtesy of author) Table 4 2 shows the average maximum force of each product tested in tension a nd the range of maximum forces for each series. Products DS1 and DL2 failed at higher loads compared to the other products tested. The average maximum force of the components tested in tension, excluding the two products with the highest results, was

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37 3690 with a 20% coefficient of variation. Failure modes of disconnect boxes are shown in Figure 4 3 Five failed in the adapter hub, four at the top connection, three cracked around the bottom, and three cracked in the top corner. Six signal heads failed by cracking at the top connection and six failed by cracking around the top surface, as shown in Figure 4 4 Table 4 2 Average ma ximum load of components, tension Test series Product Component Average maximum load (lb) Range of maximum load (lb) T15 DS1 Small disconnect box 5970 5770 6350 T16 DS2 Small disconnect box 4887 4490 5540 T17 DL1 Large disconnect box 3330 3060 3370 T 18 DL2 Large disconnect box 7283 6020 7940 T19 DL3 Large disconnect box 3373 2260 4270 T20 SH1 Signal head 3860 3610 4300 T21 SH2 Signal head 3220 2290 3400 T22 SH3 Signal head 3150 3110 3170 T23 SH4 Signal head 4310 4290 4330 A B C D Figu re 4 3 Disconnect box failure modes, tension A) Adapter hub B) Top connection. C) Top corner. D) Around bottom. (Photos courtesy of author)

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38 A B Figure 4 4 Signal head failure modes, tension A) Top connection B) Around top surface. (Photos courtesy of author) 4.1.2 Test Observations Flexure results of disconnect boxes and signal heads show a similar range of failure values. Disconnect boxes faile d in the range of 250 to 437 lbs while signal heads failed in the range of 237 to 451 lbs. Therefore, depending on the combination of products used, failure could occur in either the disconnect box or the signal head. The most common failure modes seen wer e cracking in the corners of the disconnect box and cracking at the top of the signal head. The range of tension testing was more spread out. Disconnect boxes failures occurred between 3330 lbs and 7283 lbs. The range of failure loads for signal heads in tension was 3150 to 4310. This would suggest the signal head is the weak link; however, excluding the two disconnect box products with higher failure loads, the values are again within a similar range. The most common failure modes were cracking in the ada pter hub followed by cracking at the top connection for disconnect boxes. Signal heads failed equally between cracking at the top connection and failing around the top surface. 4.2 Reinforced Component Tests Tests using available retrofit reinforcement we re performed on a representative small disconnect, large disconnect, signal, and combination in order to evaluate the

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3 9 effect of the reinforcement on breaking strength. The results from individual tests, series T1 T9 for flexure and T15 T23 for tension, wer e used to determine which components would be used for combination and reinforced testing. The weakest of the large disconnect box and signal head products were chosen for reinforced testing in order to evaluate the maximum effect of reinforcement. Of the large disconnect boxes, product DL3 failed at the lowest load in flexure and close to the lowest load in tension and was therefore chosen for combination and reinforced testing. Signal head SH3 failed at the lowest load for both flexure and tension. Produc t DS2 was used for reinforced testing of small disconnects owing to the failure mode seen during non reinforced testing. Two out of three replication s of DS2 in flexure failed in the adapter hub, and it was chosen in order to record the effect of reinforce ment on the adapter hub failure. Reinforced product IDs and corresponding non reinforced product IDs are shown in Table 4 3 for reference. Table 4 3 Product IDs for reinforced testing Reinforced product ID Non reinforced product ID RDS1 DS2 RDL1 DL3 SH3 SH3 C1 DL3 and SH3 RC1 DL3 and SH3 4.2.1 Test Results Table 4 4 shows results of reinforced flexure tests, reporting average maximum load and the range of maximum load for each test series. Failure modes were also recorded, Reinforced disconnect boxes failed during flexure tests by beginning to crack in the top corner and then continuing to crack around the reinforcemen t, an example of which is shown in Figure 4 5 All three reinforced signal heads cracked at the top

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40 connection in flexure, as shown in Figure 4 6 Table 4 4 Average maximum load of reinforced components, flexure Test series Product Component Average maximum load (lb) Range of maximum load (lb) T11 RDS1 Reinforced small disconnect 418 385 453 T12 RDL1 Reinforced large disconne ct 187 169 208 T13 RSH1 Reinforced signal head 299 273 318 Figure 4 5 Reinforced disconnect box failure mode, flexure (photo courtesy of author) Figure 4 6 Reinforced signal failure mode, flexure (photo courtesy of author) Table 4 5 shows results of reinforced tension tests. During tension tests, large disconnect boxes failed by cracking around the top reinfo rcement while small disconnect boxes failed by cracking in the top corners as shown in Figure 4 7 Each of the three reinforced signal heads cracked at the back edge of the reinforcement in tension, as shown in Figure 4 8 Table 4 5 Average maximum load of reinforced components, tension Test series Product Component Average maximum load (lb) Range of maximum load (lb) T25 RDS1 Reinforced small disconnect 6273 5770 7270 T26 RDL1 Reinforced large disconnect 4053 3000 4600 T27 RSH1 Reinforced signal head 3900 3850 3980

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41 A B Figure 4 7 Reinforced disconnect box failure modes tension A) Large disconnect. B) Small disconnect. ( P hotos courtesy of author) Figure 4 8 Reinforced signal failure mode, tension (photo courtesy of author) 4.2.2 Test Observations Reinforced tests w ere performed in order to evaluate the available methods for strength improvement. Table 4 6 shows the percent difference of reinforced to non reinforced results for both flexure and tension. The average percent increase of breaking strength provided by r einforcement during flexure tests was 8%. Table 4 6 Reinforced to non reinforced ratio of maximum load Product Percent difference in failure load, flexure Percent difference in failure load, tension RDS1 11 28 RDL1 25 20 RSH1 26 24 RC1 20 16 Results of reinforced and corresponding non reinforced flexure results are shown graphically in Figure 4 9. The results do not show a strong indication that reinforcement si gnificantly improves breaking strength of components. The results do show that a discussion of failure modes is important while considering the effect of reinforcement. In

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42 flexure, the most common failure modes of disconnect boxes was failure in either the top or bottom corners. The available reinforcement did not extend to those areas, having little effect on breaking strength. The tested reinforcement should, however, affect the adapter hub and top connection failure modes. Non reinforced components that failed in the adapter hub failed in the corners during reinforced testing, but at only slightly increased loads. Signal heads saw more of a punching action and still failed at the top connection around the back of the reinforcement. Figure 4 9 Comparison of reinforced to non reinforced results, flexure A comparison of reinforced and corresponding non reinforced tension results are presented in Figure 4 10. As with flexure, there is no strong indication that reinforcement had an appreciable effect on component strength. Disconnect box failure modes observed during reinforced tension testing were less varied than with non reinforced testing. Failures occurred around t he top reinforcement and in the top 0 100 200 300 400 500 600 Small Disconnect Large Disconnect Signal Head Combination Maximum Force (lb) Product Non reinforced Reinforced

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43 corners. However, non reinforced failure modes such as adapter hub and cracking in the bottom were seen mostly in products that were not used during reinforced testing, so the testing was not able to evaluate the effect of reinforcement on all failure modes. Signal heads failed around the back of the top reinforcement as compared to cracking in the top front during non reinforced testing Figure 4 10 Comparison of reinfo rced to non reinforced results 4.3 Non reinforced and Reinforced Combination Tests Combination tests were performed in both flexure and tension in order to verify that components behave the same in a system as during individual testing. Products DL3 and S H3 were used in order to compare combination results to the weakest components from individual testing and to compare reinforced to non reinforced combination results. 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 Small Disconnect Large Disconnect Signal Head Combination Maximum Force (lb) Product Non reinforced Reinforced

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44 4.3.1 Test Results Results of both non reinforced and reinforced combination tests in fl exure are shown in Table 4 7 along with corresponding individual component results for comparison. Combination test series T10 corresponds to component test series T5 and T8. T14 corresponds to T12 and T13. Two no n reinforced combinations failed at the top of the disconnect in flexure, and one failed at the top of the signal head. Reinforced combinations failed at the top of the disconnect box in flexure. Examples of these failure modes are shown in Figure 4 11 and Figure 4 12 Table 4 7 Average maximum load of combinations, flexure Test series Product Component Average maximum load (l b) Range of maximum load (lb) T5 DL3 Large disconnect box 250 207 292 T8 SH3 Signal head 237 185 282 T10 C1 Combination 226 184 302 T12 RDL1 Reinforced large disconnect 187 169 208 T13 RSH1 Reinforced signal head 298 273 318 T14 RC1 Reinforced combin ation 271 242 319 A B C Figure 4 11 Combination failure modes, flexure A) Top of disconnect. B) Corners of disconnect. C)Top of signal. (P hotos courtesy of author) Figure 4 12 Reinforced combination failure mode, flexure (photo courtesy of author)

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45 Table 4 8 shows both non reinforced and reinforced combination results in tension, along with correspondi ng individual product results for comparison. Test series T24 corresponds to T19 and T22 while test series T28 is the combination of components used in T26 and T27. Each replication of non reinforced combinations failed at the top of the signal in tension, as shown in Figure 4 13. Reinforced combinations failed in the signal head, as shown in Figure 4 14. Table 4 8 Average max imum load of combinations, tension Test series Product Component Average maximum load (lb) Range of maximum load (lb) T19 DL3 Large disconnect box 3373 2260 4270 T22 SH3 Signal head 3150 3110 3170 T24 C1 Combination 3260 2970 3460 T26 RDL1 Reinforced l arge disconnect 4053 3000 4600 T27 RSH1 Reinforced signal head 3900 3850 3980 T28 RC1 Reinforced combination 3743 2950 4390 Figure 4 13 Combination failure mode, tension (photo courtesy of author) Figure 4 14 Reinforced combination failure mode, tension (photo courtesy of author) 4.3.2 Test Observations The goal of combination testing was to verify that individual products behave as

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46 they would in a system during testing. It was expected that the weakest of the components from individual testing fails in a system at an equivalent load during combination testing. Non reinforced combination testing in flexure resulted in two different failure locatio ns at an average load of 226 lbs. Two combinations failed at the top of the disconnect while one failed at the top of the signal. The individual product failure loads for disconnects and signals were very close, disconnects being 250 lbs and signals being 237 lbs, demonstrating that the results of combination testing agree with individua l testing. Reinforced combinations failed in flexure in the top of the disconnect box. That was shown to be the weakest link during individual reinforced testing. The combin ation failed at a slightly higher load than the disconnect box alone, an average of 271 lb to 187 lb respectively, but can be considered within an acceptable range when considering the scatter of RDL1 data. All three replication s of non reinforced combinat ions in tension failed at the top of the signal head, which was the weakest link during individual component testing. Signals in combinations showed very similar cracking patter ns as individual signal heads. Each of the replication s of reinforced combinati ons tested in tension failed in the signal head. The average of the individual product failure loads were statistically identical, signal heads failing at 3900 lb and disconnect boxes at 4053 lb. The combination failed at an average of 3740 lb which is wit hin the expected range based on individual testing. By comparing combination results to component results of both non reinforced and reinforced systems, it can be concluded that the behavior of the system as a whole

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47 is consistent with the behavior of each component during individual testing. It is reasonable to impose a test standard on each component type and expect the individual improvements to translate to the system. Product results show that signals and disconnect boxes generally fail at similar load s, so improvement of one part of the system is not enough. The performance of the signal system will only be improved if the capacity of both components is improved. 4.4 Summary of Test Results and Observations A total of 84 tests were completed to determi ne the strength of non reinforced disconnect boxes, signal heads, and sample reinforced components. Tests on a combined system were also completed to verify the assumption that individual components will act as they do in a system. Tests were performed in both flexure and tension with 3 replications per test series. Points of interest during testing were failure loads of individual products, behavior of components as compared to combinations, and the effect of reinforcement on performance of signals and dis connect boxes. The results of non reinforced flexure component tests are shown graphically in Figure 4 15 Results show that signal heads and disconnect boxes have a similar range of breaking strength in flexure. The average breaking strength of components in flexure was 343 lb with a 26% coefficient of variation. Disconnect boxes most commonly failed in the corners in flexure; signal heads most commonly failed at the top connection. Figure 4 16 shows a summary of the results of each non reinforced component test performed in tension. With the exception of two disconnect box products which had larger breaking strengths, signal heads and disconnect boxes again have a similar range of breaking strength in tension. The average breaking strength of components in

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48 tension was 3690 lb with a 20% coefficient of variation, excluding the two highest valued test series. Disconnect boxes most commonly failed in the adapter hub in tensio n; signal heads failed equally between the top connection and a break around the top surface. For both test types, results did not indicate that reinforcement provided significant increases in strength performance of components. Finally, results showed tha t combinations failed at the location and general load of the weakest component from individual testing. Figure 4 15 Non reinforced component results, flexure 0 100 200 300 400 500 600 Small Disconnect T1 Small Disconnect T2 Large Disconnect T3 Large Disconnect T4 Large Disconnect T5 Signal Head T6 Signal Head T7 Signal Head T8 Signal Head T9 Maximum Force (lb) Product

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49 Figure 4 16 Non reinforced component results, tension 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 Small Disconnect T15 Small Disconnect T16 Large Disconnect T17 Large Disconnect T18 Large Disconnect T19 Signal Head T20 Signal Head T21 Signal Head T22 Signal Head T23 Maximum Force (lb) Product

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50 CHAPTER 5 RECOMMENDATIONS Objectives of this report include assessing test options for product evaluation testing and developing recommendations on breaking strength criteria for improved hurricane res istance. 5.1 Advantages and Disadvantages of Testing Options Test options for product evaluation include requiring flexure tests, tension tests, or both. In order to assess the test options, the benefits and drawbacks of each are presented in the followi ng sections. 5.1.1 Flexure Advantages: The benefit of flexure tests is that the prying action at the top of each component is captured. The weakness of the top corners of the disconnect box was apparent during flexure tests. Disadvantages: The drawback to testing in flexure alone is that some failure modes will not be represented. Disconnect boxes failed in the adapter hub most often in tension while that failure mode was not common in flexure. Signal heads in flexure saw almost exclusively the failure m ode of cracking at the top connection, not accounting for the failure of a break off of the whole top surface. Also, the benefits of alternative methods of strengthening, such as the use of a cable or rod through the system, may not be quantified in flexur e while providing significant increase in tensile strength. 5.1.2 Tension Advantages: The benefits of tension tests are that they allow for the evaluation of the adapter hub failure mode better than flexure tests. Tension tests also resulted in an even am ount of failures between the top connection and a break off of the top

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51 surface in signal heads. They can also be performed in any test lab with a universal testing machine. Disadvantages: The most common failure of cracking in the top corners during flexu re was the least common seen failure mode during tension. Also, although a loose correlation between flexure and tension test results exists, the products DS1 and DL2 were shown to be significantly stronger than comparable products in tension while showing slightly below and slightly above average results, respectively, in flexure. Tension testing alone would show these products to be superior, but when loaded in flexure that would not be the case. 5.1.3 Ratio of Tension to Flexure One aspect of the discuss ion is the potential of a correlation between flexure and tension results. The ratios of the maximum tension load to maximum flexure load for each product are presented in Table 5 1 The average ratio is 13 with a coefficient of variation of 22%. The data suggests that there is a correlation between tension and flexure strength; however this ratio is not the only consideration when determining what tests are most effective. Failure modes should also be considered, a s well as the ability of each test to represent loads for each type of signal support system. Table 5 1 Ratio of maximum tension load to maximum flexure load Product Ratio of Tension to Flexure DS1 17.7 DS2 13.0 DL1 9.5 DL2 16.7 DL3 13.5 SH1 8.6 SH2 10.7 SH3 13.3 SH4 12.3

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52 5.2 Testing Recommendations Based on observations of failure modes made during testing, it is recommended that both flexure and tension tests be required for product qualification. Recommendations for load criteria were determined by considering AASHTO design wind loads on traffic signals and the dynamic effects felt by the system. 5.2.1 AASHTO Wind Load Determination Design procedures in AASHTO 2009 were used to determine an estim ate design determining design pressures from wind velocities using the equation (5 1) P z = 0.00256 K z GV 2 I r C d (5 1) where K z is a height and exposure factor, G is a gust effect factor, V is design velocity, I is the importance factor, and C d is the drag coefficient. The code provides methods for determining each of these factors. K z th e height and exposure factor, was obtained from Table 3 5 of AASHTO 2009. The gust effect factor, G accounts for the dynamic nature of the effect of wind on a structure. G was taken as 1.14, as the minimum recommendation in the document. The design velocit y is based off of basic wind speed maps. 150 mph was used as a worst case wind speed in Florida for Occupancy Category II as provided in AASHTO 2009. The importance factor relates to design life of the structure, and will be 1.0 for this case. AASHTO recom mends a drag coefficient of 1.2 according to Table 3 6; however, according to Cook et al. (2010), 0.45 can be used as a conservative drag coefficient for span wire traffic signals. Using these factors in equation 5 1, the design pressure was determined to be 26.6 psf.

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53 Applying the AASHTO design pressure over the total area of a 5 section disconnect, signal, and backplate system with an area of approximately 14 ft 2 the resulting design force on a signal becomes 370 lb. The design value is slightly larger th an the 343 lb average of results from flexure tests indicating that failures would certainly be expected in high wind events.5.2.2 Dynamic Effects There is potential for dynamic effects on signal components during a hurricane, and so a dynamic amplificati on factor was considered in order to try to account for movement of traffic signals under high velocity wind loading. In dynamic applications, a 100% load amplification is the upper limit of a rigid object subjected to a constant dynamic load, neglecting t he dynamics of oscillation of the entire structure (Tedesco et al., 1999). The full dynamic factor of 2.0 is recommended as a conservative value for signal components, however, the dynamics of the full system are complex and this factor may not take into a ccount the movement or damping of the entire system. Recommended load criterion for flexure was determined by applying the dynamic factor to the AASHTO wind load of 370 lb, resulting in a requirement of 740 lb for flexure. Although a tension design load ca nnot be determined directly from AASHTO procedures, a comparison of the flexure design load to the average of the test results suggests that average test results approximated the design loads. Based on this relationship, the average of the tension test res ults was used as an estimate to determine a tension criterion. A dynamic amplification factor of 2.0 was also used for tension requirements to be consistent for dynamic behavior of the system. Applying the dynamic amplification factor to the average of the tension test results produced a recommended load requirement of 7400 lb for tension.

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54 5.3 Suggestions on Possible Improvements The goal of FDOT is to improve public safety by enhancing the performance of span wire signals during and after hurricanes. One approach may be to consider the distinction between ultimate limit state and serviceability limit state. The ultimate limit state is reached when failures result in collapse of the structure. In the case of span wire signals, damage to a signal severe eno ugh to result in a nonoperational intersection would be past its ultimate limit state. The serviceability limit state occurs when a structure has been damaged but is still considered useful to preserve life safety. Based on observations during testing, it may be useful to consider serviceability of traffic signals. For example, a design incorporating a cable or threaded rod through the middle of the disconnect box may allow for structural damage to occur in the signal or disconnect box while maintaining the operational function of the signal until it is able to be repaired. This design, or similar approach, would allow higher rotations to occur after the outer structure has failed resulting in decreased visibility, but could maintain the function of a signal ized intersection. 5.4 Summary of Recommendations To improve the performance of span wire traffic signal support systems, the suggested load qualification for signals and disconnect boxes is 740 lb in flexure and 7400 lb in tension. These values were dete rmined by determining wind loads using AASHTO 2009 procedures and considering the dynamic effects of wind. Product testing should be performed using both tension and flexure tests in order to evaluate common failure modes for each respective loading. Final ly, failure modes observed during testing should be considered while determining possible improvements to the system. Targeted

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55 improvement of proven weaker areas may result in significant improvement in the performance of traffic signals under hurricane wi nd loading.

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56 APPENDIX A TEST RESULTS AND FAILURE MODES FOR EACH TEST Figure A 1 Test series 1: DS1 in flexure Figure A 2 DS1.1 failure mode, crack in bottom corner Figure A 3 DS1.2 failure mode, crack in bottom corner Figure A 4 DS1.3 failure mode, crack in bottom corner

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57 Figure A 5 Test series 2: DS2 in flexure Figure A 6 DS2.1 failure mode, adapter hub failure Figure A 7 DS2.2 failure mode, adapter hub failure Figure A 8 DS2.3 failure mode, crack in top corner

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58 Figure A 9 Test series 3: DL1 in flexure Figure A 10 DL1.1 failure mode, crack in bottom corner Figure A 11 DL1.2 failure mode, crack in top corner Figure A 12 DL1.3 failure mode, crack in top corner

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59 Figure A 13 Test series 4: DL2 in flexure Figure A 14 DL2.1 failur e mode, attachment hardware Figure A 15 DL2.2 failure mode, attachment hardware Figure A 16 DL2.3 failure mode, attachment hardware

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60 Figure A 17 Test series 5: DL3 in flexure Figure A 18 DL3.1 failure mode, crack at top connection Figure A 19 DL3.2 failure mode, crack in top corner Figure A 20 DL3.3 failure mode, crack in top corner

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61 Figure A 21 Test series 6: S H1 in flexure Figure A 22 SH1.1 failure mode, crack at top connection Figure A 23 SH1.2 failure mode, crack at top connection Figure A 24 SH1.3 failure mode, crack at top connection

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62 Figure A 25 Test series 7: SH2 in flexure Figure A 26 SH2.1 failure mode, crack at top connection Figure A 27 SH2.2 failure mode, crack at top Figure A 28 SH2.3 failure mode, break off ar ound top surface

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63 Figure A 29 Test series 8: SH3 in flexure Figure A 30 SH3.1 failure mode, crack at top connection Figure A 31 SH3.2 failure mode, crack at top connection Figure A 32 SH3.3 failure mode, crack at top connection

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64 Figure A 33 Test series 9: SH4 in flexure Figure A 34 SH4.1 failure mode, crack at top connection Figure A 35 SH4.2 failure mode, crac k at top connection Figure A 36 SH4.3 failure mode, crack at top connection

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65 Figure A 37 Test series 10: C1 in flexure Figure A 38 C1.1 failure mode, crack at top of disconnect Figure A 39 C1.2 failure mode, crack around top of disconnect Figure A 40 C1.3 failure mode, crack at top of signal

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66 Figure A 41 Test series 11: RDS1 in flexure Figure A 42 RDS1.1 failure mo de, crack in top corner Figure A 43 RDS1.2 failure mode, crack in top corner Figure A 44 RDS1.3 failure mode, crack in top corner

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67 Figure A 45 Test series 12: RDL1 in flexure Figure A 46 RDL1.1 failure mode, crack starting in top corner Figure A 47 RDL1.2 failure mode, crack starting in top corner Figure A 48 RDL1.3 failure mode, crack starting in top corner

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68 Figure A 49 Test series 13: RSH1 in flexure Figure A 50 RSH1.1 failure mode, punching at top connection Figure A 51 RSH1.2 failure mode, crack ing in top connection Figure A 52 RSH1.3 failure mode, cracking in top connection

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69 Figure A 53 Test series 14: RC1 in flexure Figure A 54 RC1.1 failure mode, crack around top Figure A 55 RC1.2 failure mode, crack around top reinforcement Figure A 56 RC1.3 failure mode, crack around top reinforcement

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70 Figure A 57 Test series 15: DS1 in tension Figure A 58 DS1.1 failur e mode, crack around bottom Figure A 59 DS1.2 failure mode, crack around bottom Figure A 60 DS1.3 failure mode, crack around bottom

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71 Fig ure A 61 Test series 16: DS2 in tension Figure A 62 DS2.1 failure mode, crack in top corner Figure A 63 DS2.2 failure mode, crack at top connection Figure A 64 DS2.3 failure mode, crack at top corner

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72 Figure A 65 Test series 17: DL 1 in tension Figure A 66 DL1.1 failure mode, adapter hub, crack around bottom Figure A 67 DL1.2 failure mode, crack in bottom corner Figure A 68 DL1.3 failure mode, crack in bottom corner

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73 Figure A 69 Test series 18: DL2 in tension Figure A 70 DL2.1 failure mode, crack in top corner Figure A 71 DL2.2 failure mode, adapter hub failure Figure A 72 DL2.3 failure mode, ad apter hub failure

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74 Figure A 73 Test series 19: DL3 in tension Figure A 74 DL3.1 failure mode, crack at top connection Figure A 75 DL3.2 failure mode, crack at top connection Figure A 76 DL3.3 failure mode, crack at top connection

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75 Figure A 77 Test series 20: SH1 in tension Figure A 78 SH1.1 failure mode, crack at top connection Figure A 79 SH1.2 failure mode, crack around top surface Figure A 80 SH1.3 failure mode, crack at top connection

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76 Figure A 81 Test series 21: SH2 in tension Figure A 82 SH2.1 failure mode, crack around back of signal Figure A 83 SH2.2 failure mode, crack at top connection Figure A 84 SH2.3 failure mode, crack at top of connection

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77 Figure A 85 Test series 22: SH3 in tension Figure A 86 SH3.1 failure mode, crack at top connection Figure A 87 SH3.2 failure mode, crack at top connection Figure A 88 SH3.3 failure mode, crack around top surface

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78 Figure A 89 Test series 23: SH4 in tension Figure A 90 SH4.1 failure mode, crack around top surface Figure A 91 SH4.2 failure mode, crack around top surface Figure A 92 SH4.3 failure mode, crack around top corner

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79 Figure A 93 Test series 24: C1 in tension Figure A 94 C1.1 failure mode, crack at top of signal Figure A 95 C1.2 failure mode, crack at top of signal Figure A 96 C1.3 failure mode, crack at top of signal

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80 Figure A 97 Test series 25: RDS1 in tension Figure A 98 RDS1.1 failure mode, crack in top corner Figure A 99 RDS1.2 failure mode, crack in top corner Figure A 100 RDS1.3 failure mode, crack in top corners

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81 Figure A 101 Test series 26: RDL1 in tension Figure A 102 RDL1.1 failure mode, crack around top reinforcement Figur e A 103 RDL1.2 failure mode, crack around top reinforcement Figure A 104 RDL1.3 failure mode, crack around top reinforcement

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82 Figure A 105 Test series 27: RSH1 in tension Figure A 106 RSH1.1 failure mode, crack in top of signal Figure A 107 RSH1.2 failure mode, crack in top of signal Figure A 108 RSH1.3 failure mode, crack in top of signal

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83 Figure A 109 Test series 28: RC1 in tension Figure A 110 RC1.1 failure mode, crack in top of signal Figure A 111 RC1.2 failure mode, crack in top of signal Figure A 112 RC1.3 failure mode, cracking in signal

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84 APPENDIX B LIST OF PARTS USED Figure B 1 Signal head Figure B 2 Disconnect box Figure B 3 Tri stud adapter with attachment hardware Figure B 4 Figure B 5 Figure B 6 Tri stud to pipe adapter for bottom of disconnect box Figure B 7 bus hing Figure B 8

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85 Figure B 9 Figure B 10 Top disconnect reinforcement Figure B 11 Large disconnect reinforcement, bottom Figure B 12 Small disconnect reinforcement, bottom Figure B 13 Signal reinforcement Figure B 14 Reinforcement attachment hardware Figure B 15 Steel washer for reinforcement connections

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86 LIST OF REFERENCES American Association of State Highway Transportation Officials (AASHTO). (2009). Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals, 5th Edition. Washington, D.C.: AASHTO American Society of Civil Engineers (ASCE). (2010). ASCE 7 10: Minimum Design Loads for Building and Other Structures Reston, VA.: ASCE Cook, R.A., Bloomquist, D., & Long, J.C. (1996). Structural Qualification Procedur e for Traffic Signals and Signs. FDOT WPI No. 0510731 University of Florida, Engineering and Industrial Experiment Station, Gainesville, FL. Cook, R.A., & Johnson, E.V. (2007). Development of Hurricane Resistant Cable Supported Traffic Signals. FDOT Cont ract No. BD545 57 University of Florida, Department of Civil and Coastal Engineering, Gainesville, FL. Cook, R.A., Masters, F.J, & Rigdon, J.L. (2012). Evaluation of Dual Cable Signal Support Systems WithPivotal Hanger Assemblies. FDOT Contract No. BDK75 977 37 University of Florida, Department of Civil and Coastal Engineering, Gainesville, FL. Florida Department of Transportation (FDOT). (2005). Hurricane Response Evaluation and Recommendations: February 11, 2005, Version 5. Tallahassee, FL.: FDOT Flo rida Department of Transportation (FDOT). (2010). Minimum Specifications for Traffic Control Signals and Devices Tallahassee, FL.: FDOT Florida Department of Transportation (FDOT). (2013). FDOT Design Standards for Design, Construction, Maintenance and U tility Operations on the State Highway System Tallahassee, FL.: FDOT Institut e of Transportation Engineers (ITE). (1985). Vehicular Traffic Control Signal Heads. Washington, D.C.: ITE Tedesco, J.W., McDougal, W. G., & Ross, C.A. (1999). Structural dyna mics: Theory and application Menlo Park, California: Addison Wesley Longman, Inc. critical materials testing up to 3,000 kN. Retrieved from http://www.tiniusolsen.com/p df/B117G.pdf

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87 BIOGRAPHICAL SKETCH Jaclyn E. Moon was born to Dr. P. David and Pat Moon in Vero Beach, Florida in 1989. She lived in Vero Beach until graduating from Sebastian River High School in 2007 and moving to Gainesville, FL to attend the Universi ty of Florida (UF) She obtained a Bachelor of Science in Civil Engineering from UF in May 2012 and a Master of Engineering in May 2013.