Numerical simulation and fragility analysis of coastal bridges with tension-compression bearings under extreme waves

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The bearing connection between the bridge girder and substructure plays a crucial role in resisting wave forces. Previous works pointed out that the box-girder bridge with laminated rubber bearings is susceptible to unseating, sliding, and overturning under extreme waves. This study develops a tension-compression (TC) bearing system to enhance the structural resistance against wave impact. A three-dimensional (3D) finite element (FE) model considering the nonlinear rubber material is established for investigating the dynamic behavior of coastal box-girder bridges, where the wave forces are imported from the computational fluid dynamics (CFD) simulations. By tracking the time histories of the reaction forces and efficient stress, four damage status levels are identified to assess the vulnerability of coastal bridges. To improve calculation efficiency, the Kriging-based surrogate model is adopted for the fragility analysis of coastal box-girder bridges under extreme waves. The results indicate that the lower plate of the bearing on the seaward side (R1) is more prone to yield under the uplifting wave forces, while the upper plate of the bearing on the landward side (R2) is more sensitive to the horizontal forces. The vertical wave force is the key influential factor of bridge damage under extreme waves. In addition, the structural capacity of the bridge with the proposed bearing system is enhanced compared with the one using the traditional laminated rubber bearing.