Rapid Assessment and Decision Making Strategies for Distortional Fatigue Multi-Girder Steel Bridges - Phase 4

Project summary:

Cracking due to distortional fatigue seldom results in catastrophic failure of multi-girder steel highway bridges, but its occurrence is frequent enough in the MnDOT bridge inventory to warrant the development of an expeditious and accurate procedure for the assessment of this problem. Such a procedure is needed to make decisions concerning possible outcomes for such bridges, including when to begin inspections, when to increase the frequency and/or scope of inspections, when to intervene with repairs, and when to demolish and replace the bridge. This research project completed an ongoing study aimed at reaching a better understanding of, and establishing a methodology for, rapid assessment of distortional fatigue in multi-girder steel bridges on skewed supports. The project was designed to refine, and reformulate if necessary, a previously developed equation for estimating stresses in steel girder webs due to out-of-plane distortion. Finite element analyses of two previously monitored bridges, as well as prototypical variations of these bridges, were used to generate the data for calibrating the stress formula.