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Inspection and Maintenance of Bridge Stay Cable Systems (2005)

Chapter: Appendix B - Statistical Analysis of Survey Results

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Page 72
Suggested Citation:"Appendix B - Statistical Analysis of Survey Results." National Academies of Sciences, Engineering, and Medicine. 2005. Inspection and Maintenance of Bridge Stay Cable Systems. Washington, DC: The National Academies Press. doi: 10.17226/13689.
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Page 72
Page 73
Suggested Citation:"Appendix B - Statistical Analysis of Survey Results." National Academies of Sciences, Engineering, and Medicine. 2005. Inspection and Maintenance of Bridge Stay Cable Systems. Washington, DC: The National Academies Press. doi: 10.17226/13689.
×
Page 73
Page 74
Suggested Citation:"Appendix B - Statistical Analysis of Survey Results." National Academies of Sciences, Engineering, and Medicine. 2005. Inspection and Maintenance of Bridge Stay Cable Systems. Washington, DC: The National Academies Press. doi: 10.17226/13689.
×
Page 74
Page 75
Suggested Citation:"Appendix B - Statistical Analysis of Survey Results." National Academies of Sciences, Engineering, and Medicine. 2005. Inspection and Maintenance of Bridge Stay Cable Systems. Washington, DC: The National Academies Press. doi: 10.17226/13689.
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Page 75

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72 APPENDIX B Statistical Analysis of Survey Results U.S. % U.S. Canada % Canada % Total Seven-wire steel strand 21 75.0 1 7.7 53.7 Steel wire 3 10.7 7 53.8 24.4 Steel bar or threadbar 1 3.6 4 30.8 12.2 Other 2 7.1 1 7.7 7.3 No answer 1 3.6 0 0.0 2.4 QUESTION 4.4 TYPE OF MAIN TENSION ELEMENT (MTE)? U.S. % U.S. Canada % Canada % Total Bare 12 42.9 0 0.0 29.3 Greased-and- sheathed 6 21.4 0 0.0 14.6 Epoxy-coated outside only 4 14.3 0 0.0 9.8 Epoxy-coated in and out 1 3.6 0 0.0 2.4 Galvanized 3 10.7 8 61.5 26.8 Stainless steel 0 0.0 0 0.0 0.0 Other 1 3.6 5 38.5 14.6 No answer 1 3.6 0 0.0 2.4 QUESTION 4.5 COATING/TREATMENT ON MAIN TENSION ELEMENT WITHIN FREE LENGTH OF CABLE? U.S. % U.S. Canada % Canada % Total Yes 9 32.1 2 15.4 26.8 No 1 3.6 9 69.2 24.4 Not known 7 25.0 2 15.4 22.0 Not applicable 10 35.7 0 0.0 24.4 No answer 1 3.6 0 0.0 2.4 QUESTION 4.6 ARE THE COATINGS/TREATMENTS ON MAIN TENSION ELEMENT DISCONTINUED OR REMOVED WITHIN THE ANCHORAGE ZONE? U.S. % U.S. Canada % Canada % Total Grout not used 6 21.4 12 92.3 43.9 Cement–water 5 17.9 0 0.0 12.2 Cement–water– admixtures 9 32.1 0 0.0 22.0 Commercial prepackaged grouts 1 3.6 0 0.0 2.4 Not known 6 21.4 0 0.0 14.6 Not applicable 0 0.0 1 7.7 2.4 No answer 1 3.6 0 0.0 2.4 QUESTION 4.7 TYPE OF GROUT USED? U.S. % U.S. Canada % Canada % Total Yes—grout 6 21.4 0 0.0 14.6 Yes—grease 10 35.7 0 0.0 24.4 Yes—other 7 25.0 2 15.4 22.0 No filler 0 0.0 11 84.6 26.8 Not known 4 14.3 0 0.0 9.8 No answer 1 3.6 0 0.0 2.4 QUESTION 4.8 ARE FILLER MATERIALS USED IN THE ANCHORAGE ZONE? U.S. % U.S. Canada % Canada % Total Wedges 6 21.4 0 0.0 14.6 Conical socket with wedges 13 46.4 2 15.4 36.6 Cylindrical sockets with wedges 0 0.0 0 0.0 0.0 “Hi-Am” type 3 10.7 0 0.0 7.3 Other 3 10.7 11 84.6 34.1 Not known 2 7.1 0 0.0 4.9 No answer 1 3.6 0 0.0 2.4 QUESTION 4.9 TYPE OF ANCHORAGE?

73 U.S. % U.S. Canada % Canada % Total HDPE with PVF (Tedlar© tape) 10 35.7 0 0.0 24.4 UV-resistant HDPE 0 0.0 1 7.7 2.4 UV-resistant HDPE with spiral on surface 7 25.0 1 7.7 19.5 HDPE with dimples on the surface 0 0.0 0 0.0 0.0 Steel pipe 2 7.1 0 0.0 4.9 No sheathing 3 10.7 9 69.2 29.3 Other 3 10.7 2 15.4 12.2 No answer 3 10.7 0 0.0 7.3 QUESTION 4.11 TYPE OF CABLE SHEATHING USED? U.S. % U.S. Canada % Canada % Total Yes 6 21.4 6 46.2 29.3 No 17 60.7 5 38.5 53.7 Not known 3 10.7 2 15.4 12.2 Not applicable 1 3.6 0 0.0 2.4 No answer 1 3.6 0 0.0 2.4 QUESTION 4.12 HAVE RAIN–WIND-INDUCED CABLE VIBRATIONS BEEN OBSERVED ON THIS BRIDGE? U.S. % U.S. Canada % Canada % Total Yes 1 3.6 2 15.4 7.3 No 20 71.4 8 61.5 68.3 Not known 5 17.9 3 23.1 19.5 Not applicable 1 3.6 0 0.0 2.4 No answer 1 3.6 0 0.0 2.4 QUESTION 4.13 HAVE MTE CORROSION PROBLEMS BEEN NOTED? U.S. % U.S. Canada % Canada % Total Yes—due to loosening of retainers 4 14.3 0 0.0 9.8 Yes—due to shearing off of retainers 1 3.6 1 7.7 4.9 Yes—due to other reasons 2 7.1 1 7.7 7.3 No, not known 12 42.9 2 15.4 34.1 Not applicable 8 28.6 9 69.2 41.5 No answer 1 3.6 0 0.0 2.4 QUESTION 4.15 IF THERE ARE NEOPRENE RINGS ON THE CABLES, HAVE THERE BEEN ANY REPORTS OF MOVEMENTS OF THE RINGS OUT OF THEIR POSITIONS? U.S. % U.S. Canada % Canada % Total Yes 18 64.3 4 30.8 53.7 No 7 25.0 9 69.2 39.0 Not known 1 3.6 0 0.0 2.4 Not applicable 1 3.6 0 0.0 2.4 No answer 1 3.6 0 0.0 2.4 QUESTION 4.14 DO CABLES HAVE NEOPRENE RINGS NEAR THE TOP AND BOTTOM ANCHORAGES? U.S. % U.S. Canada % Canada % Total Yes 7 25.0 0 0.0 17.1 No 13 46.4 7 53.8 48.8 Not tested 3 10.7 6 46.2 22.0 Not known 3 10.7 0 0.0 7.3 Not applicable 1 3.6 0 0.0 2.4 No answer 1 3.6 0 0.0 2.4 QUESTION 4.16 HAS MOISTURE BEEN FOUND IN ANY OF THE INTERNAL COMPONENTS OF STAY CABLES SUCH AS THE BOTTOM ANCHORAGE AREAS? U.S. % U.S. Canada % Canada % Total Yes 1 3.6 2 15.4 7.3 No 25 89.3 10 76.9 85.4 Not known 0 0.0 1 7.7 2.4 Not applicable 1 3.6 0 0.0 2.4 No answer 1 3.6 0 0.0 2.4 QUESTION 4.17 HAS FATIGUE OF MTE OR OTHER COMPONENTS OF STAY CABLES BEEN OBSERVED? U.S. % U.S. Canada % Canada % Total Yes 6 21.4 1 7.7 17.1 No 21 75.0 12 92.3 80.5 No answer 1 3.6 0 0.0 2.4 QUESTION 4.10 DO CABLES GO OVER ÒSADDLES” ON THE PYLONS?

74 U.S. % U.S. Canada % Canada % Total Yes—from the beginning 4 14.3 0 0.0 9.8 Yes—retrofitted to correct vibrations 2 7.1 3 23.1 12.2 No 21 75.0 10 76.9 75.6 No answer 1 3.6 0 0.0 2.4 QUESTION 4.18 DO THE CABLES HAVE VISCOUS DAMPERS INSTALLED AT DECK OR TOWER LEVELS? U.S. % U.S. Canada % Canada % Total Yes—from the beginning 6 21.4 2 15.4 19.5 Yes—retrofitted to correct vibrations 3 10.7 1 7.7 9.8 No 18 64.3 10 76.9 68.3 No answer 1 3.6 0 0.0 2.4 QUESTION 4.19 DO THE CABLES HAVE CROSS CABLES INSTALLED BETWEEN THEM? U.S. % U.S. Canada % Canada % Total Yes—tuned mass dampers 0 0.0 0 0.0 0.0 Yes—other dampers 3 10.7 3 23.1 14.6 No 24 85.7 10 76.9 82.9 Not known 0 0.0 0 0.0 0.0 No answer 1 3.6 0 0.0 2.4 QUESTION 4.20 DO CABLES HAVE OTHER DAMPERS (OTHER THAN VISCOUS OR NEOPRENE RINGS) TO CONTROL VIBRATIONS? U.S. % U.S. Canada % Canada % Total Yes—sheathing 3 10.7 0 0.0 7.3 Yes—connections 1 3.6 0 0.0 2.4 Yes—both 0 0.0 0 0.0 0.0 No 17 60.7 5 38.5 53.7 Not known 1 3.6 0 0.0 2.4 Not applicable 4 14.3 8 61.5 29.3 No answer 2 7.1 0 0.0 4.9 QUESTION 4.21 HAS CRACKING OF THE CABLE SHEATHING OR SHEATHING CONNECTIONS BEEN NOTED? U.S. % U.S. Canada % Canada % Total Yes—cracking 1 3.6 0 0.0 2.4 Yes—misalignment 4 14.3 0 0.0 9.8 Yes—both 0 0.0 0 0.0 0.0 No 17 60.7 2 15.4 46.3 Not known 3 10.7 0 0.0 7.3 Not applicable 2 7.1 11 84.6 31.7 No answer 1 3.6 0 0.0 2.4 QUESTION 4.22 HAS CRACKING OR MISALIGNMENT OF THE GUIDE PIPES BEEN NOTED? U.S. % U.S. Canada % Canada % Total Yes—minor damage 5 17.9 1 7.7 14.6 Yes—moderate damage 1 3.6 0 0.0 2.4 Yes—extensive damage 1 3.6 0 0.0 2.4 No 9 32.1 2 15.4 26.8 Not known 0 0.0 1 7.7 2.4 Not applicable 11 39.3 9 69.2 48.8 No answer 1 3.6 0 0.0 2.4 QUESTION 4.23 IF THERE IS PROTECTIVE TAPE WRAPPED AROUND THE CABLE SHEATHING, HAVE THERE BEEN REPORTS OF DETERIORATION OF THE TAPE? U.S. % U.S. Canada % Canada % Total Yes 4 14.3 1 7.7 12.2 No 19 67.9 6 46.2 61.0 Not known 1 3.6 0 0.0 2.4 Not applicable 1 3.6 3 23.1 9.8 Other 2 7.1 0 0.0 4.9 No answer 1 3.6 3 23.1 9.8 QUESTION 4.24 HAVE ANY PROBLEMS ASSOCIATED WITH NEOPRENE BOOTS BEEN NOTED?

75 U.S. % U.S. Canada % Canada % Total Acoustic wire break detection 3 10.7 1 7.7 9.8 Vibration monitoring 2 7.1 1 7.7 7.3 Force measurements 0 0.0 0 0.0 0.0 Other 0 0.0 0 0.0 0.0 Not performed 21 75.0 11 84.6 78.0 Not known 1 3.6 0 0.0 2.4 No answer 1 3.6 0 0.0 2.4 QUESTION 4.26 TYPES OF SENSOR-BASED LONG-TERM MONITORING PERFORMED ON THE CABLES? U.S. % U.S. Canada % Canada % Total Yes 8 28.6 4 30.8 29.3 No 19 67.9 9 69.2 68.3 Not known 0 0.0 0 0.0 0.0 No answer 1 3.6 0 0.0 2.4 QUESTION 4.27 HAVE THE CABLES ON THIS BRIDGE (OR ANY OF THEIR COMPONENTS) BEEN REPAIRED? U.S. % U.S. Canada % Canada % Total Yes 3 10.7 0 0.0 7.3 No 20 71.4 5 38.5 61.0 Not known 1 3.6 0 0.0 2.4 Not applicable 3 10.7 8 61.5 26.8 No answer 1 3.6 0 0.0 2.4 QUESTION 4.28 HAS THE SHEATHING BEEN PARTIALLY REMOVED ON ANY OF THE CABLES TO EXAMINE CONDITION OF GROUT (IF APPLICABLE) AND/OR THE MTE? U.S. % U.S. Canada % Canada % Total Yes 22 78.6 8 61.5 73.2 No 1 3.6 2 15.4 7.3 Not known 4 14.3 3 23.1 17.1 No answer 1 3.6 0 0.0 2.4 QUESTION 4.29 CAN THE STRANDS OR CABLES BE REPLACED IF NEEDED? U.S. % U.S. Canada % Canada % Total Yes 20 71.4 1 7.7 51.2 No 6 21.4 12 92.3 43.9 Not known 0 0.0 0 0.0 0.0 No answer 2 7.1 0 0.0 4.9 QUESTION 4.30 DO YOU HAVE AN INSPECTION AND MAINTENANCE MANUAL FOR THIS BRIDGE? U.S. % U.S. Canada % Canada % Total Yes 11 39.3 12 92.3 56.1 No 8 28.6 0 0.0 19.5 Not known 9 32.1 1 7.7 24.4 QUESTION 5 BASED ON YOUR EXPERIENCE AND IN GENERAL, DO YOU BELIEVE THAT THE CURRENT INSPECTION, TESTING, MONITORING, AND REPAIR METHODS AVAILABLE TO YOU FOR STAY CABLES ARE EFFECTIVE AND ADEQUATE? U.S. % U.S. Canada % Canada % Total Yes 25 89.3 12 92.3 90.2 No 0 0.0 0 0.0 0.0 Not known 3 10.7 0 0.0 7.3 QUESTION 10 DO YOU BELIEVE THAT AN UP-TO-DATE RESOURCE SUCH AS A NATIONAL DATABASE OF INFORMATION ON STAY CABLE INSPECTION METHODS, REPAIRS, AND TESTING WOULD BE A USEFUL TOOL? U.S. % U.S. Canada % Canada % Total Magnetic 1 3.6 1 7.7 4.9 X-ray 1 3.6 0 0.0 2.4 Ultrasonic 1 3.6 1 7.7 4.9 Vibration-based force measurements 9 32.1 3 23.1 29.3 Other 1 3.6 0 0.0 2.4 Not performed 13 46.4 10 76.9 56.1 Not known 0 0.0 0 0.0 0.0 No answer 2 7.1 0 0.0 4.9 QUESTION 4.25 TYPES OF NON-DESTRUCTIVE TESTS THAT ANY OF THE CABLES ON THIS BRIDGE HAVE BEEN SUBJECTED TO?

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TRB’s National Cooperative Highway Research Program (NCHRP) Synthesis 353: Inspection and Maintenance of Bridge Stay Cable Systems identifies and explains various inspection and maintenance techniques for bridge stay cable systems. It discusses both short- and long-term approaches. The report information on methods for inspections and assessments, including nondestructive testing and evaluation procedures; repair and retrofit; methods for control of cable vibrations, including rain–wind vibrations; stay cable fatigue and failure; effectiveness of various inspection and repair methods; limitations of available technologies; and trends and recommendations for future study.

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