Overheight impact on bridges: A computational case study of the Skagit River bridge collapse

Abstract

Overheight truck impact can cause extensive damage to highway bridges and even lead to bridge collapse. Recent survey data indicates that the majority of overheight impact accidents were caused by tractor-semitrailers. However, the conditions under which these types of trucks can cause bridge collapse have been rarely studied. This paper provides a detailed computational study of the collapse of the Skagit River Bridge caused by an overheight tractor-semitrailer impact. Key insights are drawn from the simulation results including the collapse mechanism of the bridge and characteristics of the impact loading delivered by the trailer. It is shown that a protection beam could have been used to mitigate the risk posed by the overheight truck and it is argued that the validated tractor-semitrailer simulation model used in this work can be used to develop a performance-based design methodology for the proposed protection system.