SEISMIC ANALYSIS MODEL CONSIDERING NONLINEAR SHEAR EFFECT FOR RC BRIDGE PIERS

Bridge piers with low aspect ratio or low transverse reinforcement are vulnerable to shear failure under seismic action. The existing fiber element model ignores the nonlinear shear deformation of piers and could not be used to model the seismic behavior of bridge piers failed in shear or flexure-shear modes. In order to simulate the seismic behavior of bridge piers, a rotation-based shear failure model was built based on 36 quasi-static test results of circular piers failed in shear or flexural-shear modes. A numerical analysis model comprising the nonlinear fiber beam column element and the zero-length shear spring element was built on OpenSees analysis platform to simulate flexural shear interaction of piers. The rotation of the end region of the pier in the analysis model was used to monitor shear failure initiation of the specimen. Before shear failure, the cyclic behavior of the pier was controlled by fiber beam column element. Then, seismic response of the pier was governed by the shear spring element to simulate the strength and stiffness degradation behavior as a result of the shear failure. The analysis model was verified through a comparison with the quasi-static test results of 12 nonlinear shear dominated circular bridge piers. The results indicate that the simulated hysteretic curves agree well with the test data, the stiffness and strength degradation of the piers as a result of shear failure could be well simulated and the rationality of the model is verified.