Sources of errors in fatigue assessment of steel bridges using BWIM

Manitoba has many ageing steel bridge structures on its highway network that are facing increased axle loads, speed, and traffic intensity, all of which accelerate their deterioration due to fatigue. An immediate replacement or rehabilitation is not feasible for the existing structures that have already approached their expected service life. The residual life of these types of structures, or their component, is estimated by conducting a fatigue evaluation and damage assessment. Field measurements are very accurate in estimating fatigue loading. This paper discusses a case study of the fatigue assessment on an ageing steel bridge in Winnipeg, Manitoba, which integrates a bridge-weighing-in-motion (BWIM) system. The South Perimeter Bridge is instrumented with a structural health monitoring system which is used to perform BWIM and fatigue analysis of the steel girder bridge. The identified sources of error in the fatigue evaluation using the BWIM system, if addressed properly, are expected to increase the accuracy of fatigue analysis.