Use of Stress Range Data in Fatigue Reliability Assessment of Highway Bridges

This paper presents a specific application in which fatigue reliability of steel girders in bridges is assessed by conducting a field measurement of stresses at key critical locations. The procedure presented is regarded as a non-destructive test method. The source of information for fatigue reliability assessment is primarily a set of stress range data collected for fatigue-critical locations in a given bridge. The compiled data is then used along with a rigorous structural analysis to estimate the extent of fatigue damage in components and the assessment of fatigue reliability of the bridge. The data compiled for this study was from several steel girder bridges. The data acquisition session for each bridge lasted for two days. It was believed that within the two-day period a major percentage of potential stress ranges experienced by each bridge would be captured. Following the analysis for the assessment of reliability of these bridges, a study was conducted to determine the cost of bridge replacement based on the extent of fatigue damage in each bridge and the estimates of bridge remaining useful lives. The paper recommends a procedure that can effectively be used in data gathering; and in a follow-up reliability and life cycle cost analysis for highway bridges.