Rapid Evaluation of a Steel Girder Bridge: Case Study

A rapid evaluation methodology for steel girder bridges was researched and executed for this study. The goal was to conduct a field evaluation and load rating within a single day. To achieve this goal, three initial tasks were performed: laboratory testing to determine rapid sensor attachment, the establishment of field instrumentation guidelines, and code development to automate the data processing of crawl-speed load-test field measurements. The instrumentation guidelines and data-processing code allow for the identification of several parameters that are critical to properly representing the functional behavior of the structure. These critical parameters include composite behavior, live-load distribution factors, and presence of span continuity. With these parameters and readily available user input values, AASHTO HL-93 live-load ratings can be determined. The overall methodology was validated through a case study of a load-restricted three-span steel girder bridge. The structure was field evaluated over 1 day to produce load ratings on site. The controlling load rating of the structure prior to testing was 0.45 (operating level), which was increased to 1.56 as a result of a reduction in live-load distribution factors and the presence of composite behavior. The findings of the research illustrate the feasibility and value for rapid assessment of bridges that can potentially be incorporated into regular bridge inspection schedules.