Failure Analysis on a Curved Girder Bridge Collapse under Eccentric Heavy Vehicles Using Explicit Finite Element Method: Case Study

Abstract

In recent years, several similar bridge overturning and collapse accidents have occurred in China. All of them occurred on bridges with continuous monolithic box girders and single-column piers that were eccentrically overloaded by heavy vehicles. In this study, an explicit nonlinear dynamic finite element method is used to analyze an accident occurred on an expressway exit ramp bridge. The entire overturning and collapse process is simulated. The results show a girder revolving around the overturning axis, which is a straight line between two supports for a bridge eccentrically loaded by heavy vehicles. When the rotation of the main girder is larger than the friction limit rotation, the sliding force is greater than the friction force between the girder and the support. This causes the main girder to slide obliquely, which can induce a horizontal reaction force, pushing the piers down and collapsing the whole bridge. This underestimates the anti-overturning ability of a bridge, based on the criterion that no support disengagement occurs under overloading conditions. Second-order effects due to girder rotation (including the increase of the overturning moment arm) must be taken into account when calculating an anti-overturning stability factor based on the overturning axis between two supports.