Abstract： Based on systematic investigation of collapsed wreckage of several single-column pier beam bridges, this paper proposes that beam bridge overturning has three stages and four possible failure modes, and the anti-overturning ability consist of deformable-body rotation, self-weight and rigid-body rotation. Moreover, a overturning calculation method matching failure mode is established after classifying traditional methods. To compare the application ability and accuracy of those methods, calculations are executed in three bridges (the Chunhui Bridge in Zhejiang Shangyu, the bridge in Hongfu section in Harbin and the ramp bridge of Ganyue Expressway). The result leads to several conclusions. First, the main failure mode of overturning is that the transverse rotation increases to a certain angle and lead to the slide of girders, especially for curved girder bridges with a small radius. Second, the calculation method proposed in JTG 3362—2018 is established based on deformable-body rotation, and its calculation result is more conserve without considering the positive effects of self-weight and rigid-body rotation. Third, self-weight contributes to the overturning ability thorough the curvity of box girder or the size of bearing. The calculation results of ultimate capacity are closer to the actual overturning load considering deformable-body and self-weight. Finally, geometric nonlinear finite element model considering the three factors of anti-overturning ability is the best way to calculate the ultimate capacity.
