Inspection Guidelines for Bridge Post-Tensioning and Stay Cable Systems Using NDE Methods (2017)

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

E-1 Illustrative Examples for Using the Inspection Guidelines A p p e n d i x e Two illustrative examples on how the inspection guidelines may be used by bridge owners and state officials are presented herein. Situations that may be faced in certain real-world scenarios are presented as a backdrop to these examples. EXAMPLE 1 This example is based on the cost-driven approach with Scenario 1 weights defined in Table 5-5. It has come to the attention of a state DOT that their post-tensioned (PT) bridges may be negatively affected by grouting procedures that have been in practice. Particularly, the agency is concerned that voids may be widespread within the ducts, both internal and external alike. Using the decision matrix, the bridge inspection division wants to conduct preliminary tests for the presence of voids among all of its 200 bridges that could be negatively affected. Since there are a large number of bridges and the program has limited funding, the agency chooses the weighted categories suggested by Scenario 1 that heavily weighs cost, followed by ease of use, accuracy, inspection requirements, and finally precision. Following the flowchart presented in Figure E-1, the agency is directed to the flowchart in Figure A-5. The flowchart in Figure A-5 displays the ranked list of applicable methods for detecting voids in various situations, depending on the location of the duct (internal, external, or anchorage region), and the duct material (metal, or nonmetal). Each ranked method also refers them to the appropriate testing procedures presented in Appendix C, which includes instructions for application, the method’s specific capabilities and limitations, and other factors. Since the parameters that influence the inspection method vary widely from bridge to bridge, and each bridge or group of particular bridges will have unique testing parameters, the agency will investigate the ranked methods successively (from highest to lowest rank) until a method is found that meets the testing requirements. Using the testing procedures, the agency could then determine the method or group of methods that could be used, given the specific capabilities and limitations required by the bridge or group of bridges. Flowchart presented in Figure A-5 indicates that IE and USE (in that order) are the two methods available for detecting voids in internal metal ducts, whereas USE is the only method capable of detecting voids in the internal nonmetal ducts. For external metal ducts, sounding is the only method available for detecting voids. However, several methods are available for detecting voids in external nonmetal ducts. The ranked list, from most preferred to least preferred includes sounding, IRT, GPR, IE, LFUT, and ECT. The flowchart also shows that USE is the only method capable of detecting voids in the anchorage regions, whereas sounding and IRT may be used to detect voids in the end caps in the anchorage zone.

E-2 Figure E-1. Layout for choosing the appropriate condition assessment flowchart. For water infiltration For voids For compromised grout For breakage For section loss For corrosion For water infiltration For compromised grout For voids For breakage Use flowchart in Figure A-1 For section loss Scenario 1 Weights Start with known condition assessment Choose weights for decision matrix Collect bridge structure files Develop flowchart based on the new ranked list of NDE techniques. For corrosion Use flowchart in Figure A-2 Use flowchart in Figure A-3 Use flowchart in Figure A-4 Use flowchart in Figure A-5 Use flowchart in Figure A-6 Use flowchart in Figure A-8 Scenario 2 Weights Use flowchart in Figure A-9 Use flowchart in Figure A-10 Use flowchart in Figure A-11 Use flowchart in Figure A-12 Use flowchart in Figure A-13 For Other Desired Weights Use flowchart in Figure A-7 For combined tendon and grout defects Use flowchart in Figure A-14 For combined tendon and grout defects

E-3 EXAMPLE 2 This example is based on the accuracy-driven approach with Scenario 2 weights defined in Table 5-5. A city has an iconic cable-stayed bridge that has great historical value to the community. During routine bridge inspection officials are alarmed to see signs of corrosion in the anchorage regions. Since the bridge’s value is high for the community and the city, any possible corrosion in the anchorage regions of the stay cable system for the single bridge should be identified. In this case the officials choose the weighted categories suggested by Scenario 2 that heavily weighs accuracy, followed by ease of use, cost, inspection requirements, and finally precision. Following the flowchart in Figure E-1, the agency is directed to the flowchart in Figure A-8. The flowchart in Figure A-8 displays the ranked list of applicable methods for detecting corrosion in various situations, depending on the location of the duct (internal, external, or anchorage region), and the duct material (metal, or nonmetal). The flowchart for corrosion in Figure A-8 directs the officials to methods for detecting corrosion in anchorage regions. As detecting corrosion in the highly congested anchorage region is by far the most difficult to detect, as shown in the flowchart there are no NDE methods that are applicable (based on this investigation). In this case the bridge inspectors may have to rely on the VT procedures, including invasive methods such as borescope. The testing procedures for all methods are referenced in the flowchart and are presented in Appendix C.

Abbreviations and acronyms used without definitions in TRB publications: A4A Airlines for America AAAE American Association of Airport Executives AASHO American Association of State Highway Officials AASHTO American Association of State Highway and Transportation Officials ACI–NA Airports Council International–North America ACRP Airport Cooperative Research Program ADA Americans with Disabilities Act APTA American Public Transportation Association ASCE American Society of Civil Engineers ASME American Society of Mechanical Engineers ASTM American Society for Testing and Materials ATA American Trucking Associations CTAA Community Transportation Association of America CTBSSP Commercial Truck and Bus Safety Synthesis Program DHS Department of Homeland Security DOE Department of Energy EPA Environmental Protection Agency FAA Federal Aviation Administration FAST Fixing America’s Surface Transportation Act (2015) FHWA Federal Highway Administration FMCSA Federal Motor Carrier Safety Administration FRA Federal Railroad Administration FTA Federal Transit Administration HMCRP Hazardous Materials Cooperative Research Program IEEE Institute of Electrical and Electronics Engineers ISTEA Intermodal Surface Transportation Efficiency Act of 1991 ITE Institute of Transportation Engineers MAP-21 Moving Ahead for Progress in the 21st Century Act (2012) NASA National Aeronautics and Space Administration NASAO National Association of State Aviation Officials NCFRP National Cooperative Freight Research Program NCHRP National Cooperative Highway Research Program NHTSA National Highway Traffic Safety Administration NTSB National Transportation Safety Board PHMSA Pipeline and Hazardous Materials Safety Administration RITA Research and Innovative Technology Administration SAE Society of Automotive Engineers SAFETEA-LU Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (2005) TCRP Transit Cooperative Research Program TDC Transit Development Corporation TEA-21 Transportation Equity Act for the 21st Century (1998) TRB Transportation Research Board TSA Transportation Security Administration U.S.DOT United States Department of Transportation

TRA N SPO RTATIO N RESEA RCH BO A RD 500 Fifth Street, N W W ashington, D C 20001 A D D RESS SERV ICE REQ U ESTED N O N -PR O FIT O R G . U .S. PO STA G E PA ID C O LU M B IA , M D PER M IT N O . 88 Inspection G uidelines for Bridge Post-Tensioning and Stay Cable System s U sing N D E M ethods N CH RP Research Report 848 TRB ISBN 978-0-309-44632-7 9 7 8 0 3 0 9 4 4 6 3 2 7 9 0 0 0 0