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6 International experience and practice (largely from scan- tion, and reliability theory. An annotated bibliography of the ning tours); most relevant research is included in Appendix D. Fabrication methods and fabrication inspection; and How owners are dealing with fracture-critical details Chapter three reports on the results of the survey of bridge that cannot be easily inspected. owners and consultant inspectors, and discusses targeted interviews. The survey was sent to 72 state DOTs, agen- cies, and provinces, such as those in Canada. Useful replies ORGANIZATION were received from 40 agencies. (It should be noted that more than 40 surveys were returned; however, a few surveys The following chapter (chapter two) presents results from the were not filled out or the agency did not have any FCBs in literature review, including a brief summary of the develop- their inventory.) One of the objectives of this survey was to ment and impact of specifications related to fatigue and frac- gather information on fracture-critical structures and how ture of steel bridges, the performance of bridges in the event bridge owners define, identify, inspect, and manage FCBs. of fractures, and classification of FCMs. Additional detail on Information related to structural failures was gathered along these subjects is also presented in Appendix A, along with with repair and retrofit policies and strategies. In addition, details on fatigue life prediction, NDE, repair and retrofit input was solicited from owners on their perceived research techniques, and the impact of high-performance steel (HPS). needs related to FCBs. Useful information was gained related In general, the literature review confirmed that research con- to inspection, failures, classification of FCBs, and costs asso- ducted to evaluate the robustness of bridges deemed to be ciated with field inspection. fracture-critical demonstrated that most bridges have consid- erable reserve strength. Studies evaluated robustness using Chapter four includes discussion of the findings, and different methods including case histories of actual fractures chapter five provides the conclusions and proposes future that occurred in service, field testing, finite-element simula- research needs.