Nonlinear numerical analysis and progressive damage assessment of a cable-stayed bridge pier subjected to ship collision

Despite many studies on barge collisions with girder bridges in the literature, this paper investigates the progressive damage behaviors and nonlinear failure modes of a cable-stayed bridge pier subjected to ship collisions using finite element (FE) simulations in LS-DYNA. The damages in the pier initiate with appearing of local shear failures in the slender columns during the ship collision stage and reach the severe cross-sectional fractures associated with the formation of plastic hinges which causes the combined shear-flexural failures during the free vibration phase of the pier response. In addition, an analytical simplified model with two-degree-of-freedom (2-DOF) is proposed to formulate the strain rate effects of the concrete materials as the dynamic increase factors in the global responses of the impacted pier. It is found that the analytical model is able to efficiently estimate the impact responses of the structure compared to those from the FE high-resolution simulations. Moreover, three different damage indices are proposed based on the pier deflection, the internal energy absorbed by the pier, and the axial load capacity of the pier columns to classify the damage levels of the pier. Finally, an efficient damage index method is determinant by comparing the calculated results with the damage behaviors of the pier observed from the FE simulations.