Analysis and mitigation of progressive collapse for steel truss girders

Abstract

Progressive collapse occurs to a structure when an initial local failure that is produced by accidental circumstances triggers a disproportionate damage. In the past 40 years, accidents owning to progressive collapse took place frequently, which were paid more and more attentions. In this paper, progressive collapse analysis was performed on a steel truss girder. The Alternate Path method, combined with the finite element method, was used on the mechanisms of progressive collapse for the system. Changes of internal forces were discussed in the system when an upper or lower chord or web member at different location failed respectively. Suggestions to prevent progressive collapse were proposed for the truss. The results show that chord members in end span are important to resisting progressive collapse while chord members at midspan and diagonal web members at end-span are susceptible to progressive collapse. Failures of these members will cause significant redistribution of forces, and progressive collapse will probably occur in the remaining structure. A promotion of ductility, redundancy of the structural system, e.g. set-up strengthen gusset plate will increase the structural resistibility to progressive collapse.