I35W Bridge Collapse: Lessons Learned and Challenges Revealed

Abstract

This article discusses the issues in structural design revealed by the highway I35W Bridge's collapse that occurred at August 1st, 2007, based on an analysis of the bridge's original design drawings, a series of detailed finite elements computations, and the material evidences disclosed by National Safety Transportation Safety Board (NTSB) official investigation. These issues include (i) the redundancy consideration for multi-span bridge; (ii) the reason for those undersized designs in that bridge; (iii) the effects of lateral force on gusset plates' load capacity in steel-truss structure; (iv) the criterion of gusset plate's stability and a thin-plate theory-based model for load-rating. This analysis concludes that the lessons learned from the I35W Bridge may have certain significance for the safety assessments of those similarly-structured steel bridges. A bridge's service life is 75 years or longer. According to a NTSB's document [37], there are more than hundreds this kind of aged bridges still in service [4].