Inelastic seismic analysis of RC bridge piers including flexure-shear-axial interaction

The effect of shear coupled with axial force variation on the inelastic seismic behaviour of<br />reinforced concrete bridge piers is investigated in this paper. For this purpose, a hysteretic axial-shear<br />interaction model was developed and implemented in a nonlinear finite element analysis program. Thus,<br />flexure-shear-axial interaction is simulated under variable amplitude reversed actions. Comparative studies<br />for shear-dominated reinforced concrete columns indicated that a conventional FE model based on flexure-axial<br />interaction only gave wholly inadequate results and was therefore incapable of predicting the<br />behaviour of such members. Analysis of a reinforced concrete bridge damaged during the Northridge<br />(California 1994) earthquake demonstrated the importance of shear modelling. The contribution of shear<br />deformation to total displacement was considerable, leading to increased ductility demand. Moreover, the<br />effect of shear with axial force variation can significantly affect strength, stiffness and energy dissipation<br />capacity of reinforced concrete members. It is concluded that flexure-shear-axial interaction should be<br />taken into account in assessing the behaviour of reinforced concrete bridge columns, especially in the<br />presence of high vertical ground motion.