Analysis of Multi-beam Steel Bridges for Fatigue

Service live-load stress ranges are almost always far below those predicted by the simplified calculations used in design. Therefore, more accurate analysis is required for a fatigue assessment. The grillage method of analysis was found to give reasonable estimates of the measured stress ranges in several steel bridges. A standard set of assumptions was developed for the analysis that is most appropriate for service load levels. The fatigue evaluation procedures of National Cooperative Highway Research Program (NCHRP) Report 299 were used to evaluate the fatigue life. These procedures are expected to give reasonable estimates of the remaining fatigue life.