Pushover analyses of slender cantilever bridge piers with strength and ductility degradation

Reinforced concrete bridge piers are often subject to spatially non-uniform deterioration which typically produces strength and ductility degradation. When piers are subject to deterioration, the sectional response is no longer uniform and the determination of the pushover curves from sectional response is no longer immediate. This paper proposes a simplified procedure to accomplish this task for RC bridge cantilever piers. The method is simplified only with respect to geometric nonlinearities and yields an accurate estimate of the ultimate displacement, free of numerical issues typical of fiber-based finite elements. The procedure is based on an iterative approach to enforce the element equilibrium under P-Delta effects induced by vertical loads and can consider arbitrary deterioration patterns through the specification of different moment-curvature response along the elevation. After validating the approach with experimental results, a parametric analysis of the influence of sectional strength and ductility degradation is carried out for the case study of a rectangular hollow RC pier. Results show that significant variations of the pier equivalent plastic hinge length can be expected because of the occurrence of deterioration in the lower part of the pier. Moreover, paper provides quantitative measure of the extent of the strength and ductility degradation.