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1 S U M M A R Y Risk-Based Inspection & Strength Evaluation of Suspension Bridge Main Cable Systems The objective of this project is to develop guidelines for risk-based inspection and strength evaluation of suspension bridge main cables using probabilistic approaches. The project focused on research that has been done regarding suspension bridge main cable systems subsequent to the publication of National Cooperative Research Program (NCHRP) project 10-57 and NCHRP 534. Given the limited number of suspension bridges in the world in comparison to other bridge types, the amount of research performed on this topic since that time is relatively limited. However, wide usage of NCHRP 534 by the engineering community since its publication in 2004 has revealed numerous questions and issues regarding the methodology. A questionnaire was prepared to gather feedback and sent out to owners of 70 suspension bridges located throughout the world (information was received from the owners of 21 bridges: 17 were parallel wire cables and four were from bridges that have cables utilizing helical strand). The information obtained in the literature review and from the survey was synthesized according to the following broad topics: Inspection procedures, testing procedures, strength determination, and remaining life. The methodology has been expanded and refined to include not only a new method of strength determination of suspension bridge main cables (using a modified version of the Random Field approach), but now also includes a new procedure for determining return cycles for main cable systems (main cables as well as suspenders, anchorage elements, etc.) as adapted from the requirements of NCHRP 782. It should be noted that large portions of the proposed Guidelines retains and uses the inspection procedures as presented in NCHRP 534 and for that reason basically uses those procedures and illustrations verbatim in this report. These procedures have gained widespread acceptance with bridge owners and engineers and they were found to be compatible with the proposed risk-based inspection practices.
