AbstractOn July 7, 2020, the Taiyangbu Bridge crossing the Changjiang River was hit by a barge loaded with sand, resulting in the collapse of the main span. Such side collisions are seldomly investigated in previous studies. To this end, high-fidelity physics-based finite-element (FE) models are developed in this study to reproduce the barge side collision accident of the Taiyangbu Bridge and scrutinize the causes of its collapse. The collapse process of the Taiyangbu Bridge obtained from the high-resolution FE simulations is consistent with that observed from the video data. The FE results indicate that the collapse of the Taiyangbu Bridge is attributed to the flexural failure of the pile foundation in the longitudinal bridge direction, which agrees with the field investigation. In addition, side collisions are demonstrated to be the most unfavorable scenario in comparison with head-on collisions and oblique collisions. Based on the vessel–bridge interaction analysis, a simplified model with two degrees of freedom (2-DOF) is proposed to efficiently predict the vessel-side-collision-induced responses. Compared with the force-based design method used in current design codes and the energy-based method, which may result in an unsafe and inadequate design, the proposed 2-DOF method is more suitable for the side collision analysis.