Estimating Seismic Response of RC Piers under Unidirectional and Bidirectional Shaking: A Mechanics-Based Approach

Abstract

Estimating seismic response of reinforced concrete (RC) structures under bidirectional excitation covering admissible incidence angles is computationally challenging and time-consuming for routine design. Further, such responses are widely scattered because of inherent variability in the characteristics of real records, especially owing to the degradation of RC members under cyclic loading. Hence, to obviate the complexity and tedium of the task, this paper suggests an approach to making an advance estimate of response under both unidirectional and bidirectional shaking for all incidence angles. To this end, response of a RC bridge pier has been computed under a set of near-fault and far-fault records. Important response indices (peak deformation and hysteretic energy) have been presented in nondimensional Π-terms choosing simple structural parameters (yield force and yield displacement) and ground motion characteristics (peak ground acceleration, root mean square acceleration, and mean period of ground motion). Representation of responses in dimensionless form reveals a shape-similar pattern. A regression model developed using these nondimensional Π-terms has been found to perform reasonably well in the statistical sense and hence can be used in practice.