Nonlinear Static Pushover Analysis of Hollow Shear Critical RC Bridge Piers Under Monotonic Loading: A Comparitive Study

Hollow RC bridge piers exhibit several failure modes when subjected to extensive time varying loads during their service lives. Shear failure of hollow RC bridge piers is very critical as it is brittle in nature involving rapid deterioration of strength with increasing widths of the shear cracks and low ductility. Hence this type of failure is not desirable in the earthquake prone areas. Simulation models that can accurately predict the characteristic load deflection curve parameters (including yield load, peak load, ultimate load and corresponding drift, ductility and post peak strength degradation) are very much essential for efficient design of these structures. In the present study, a nonlinear static pushover analysis of three hollow rectangular RC bridge piers (one flexure critical and two shear critical) has been performed under monotonic loading using four different analysis techniques. The first type of simulation model used in the present study is based on the commonly used fiber based nonlinear beam-column elements with simple uniaxial material constitutive relationships, which are very effective in predicting the flexural response of bridge piers. The second type of simulation model used in the present study is also based on simple fiber based nonlinear beam-column elements. However, the constitutive relationships of steel in this model are modified to predict the post-peak strength degradation in shear critical bridge piers. The third type of simulation model is based on two dimensional (2D) CSMM based smeared RC plane stress elements. The fourth type of simulation model is an analytical model based on the sectional analysis method. The load deflection curve properties obtained from all the simulation models have been compared with each other and also with the experimental data. It has been concluded from the present study that all four models are equally efficient in predicting the behaviour of flexure critical bridge pier. However, in the case of shear critical bridge piers, predictions from the 2D CSMM based simulation model are more accurate.