Failure assessment and virtual scenario reproduction of the progressive collapse of the FIU bridge

摘要

The Florida International University pedestrian bridge in the United States is a two-span prestressed reinforced concrete bridge, which collapsed during its construction in March 2018. In this study, a finite element (FE) numerical simulation is performed to reproduce the virtual scenario of the bridge collapse and examine the cause of this accident. A refined FE model is established on the basis of the concrete plastic damage constitutive relations, and the damage factor is calculated using the Najar damage theory. When the model is combined with the alternative path method, the complete simulation of the structural damage and the collapse process is obtained. Especially, two key features of the structural response process, i.e. the instantaneous image of the collapse behavior and the total time of collapse 1.2 s, are almost identical with that recorded in the video. Simulation results can accurately reproduce the entire collapse process, indicating that the computational strategy used in this study are appropriate. Further investigation on the deformation and failure modes at different times during the collapse process and a discussion on the critical role of key components in the progressive collapse are presented. Analysis results show that the collapse of the structure is caused by the destruction of local nodes; the structural robustness analysis is crucial for the collapse resistance design. Numerical results and conclusions can provide a reference for the cause of bridge collapse accidents. The critical information of the finite element analysis process is presented in detail.