Multi-spring model for tubular rocking steel bridge piers subjected to earthquake loading.

Recent decades have seen increased interest in using the controlled rocking concept in seismic resisting systems. Unlike conventional systems, where lateral deformation of a member is achieved through the formation of plastic hinges in critical regions, in the rocking systems this is achieved through a gap opening mechanism. Due to gravity load and/or post-tensioning forces, the rocking systems exhibit a self-centering behavior. Conducting a continuum finite element analysis to investigate the seismic response of such a system is quite expensive in terms of computational resources. On the other hand, a simplified macro model using two springs to simulate the gap opening/closing mechanism cannot accurately predict the dynamic response of the system. This study utilizes a multiple-spring model to simulate the nonlinear seismic response of circular tubular steel piers. An efficient optimization procedure based on a genetic algorithm is developed to calibrate the parameters of the springs. The results of continuum finite element analyses are compared with those obtained from the multi-spring model to verify the accuracy of the model. The proposed method is shown to be advantageous for accurately simulating the seismic response of a bridge model subjected to multi-directional ground motions, particularly the hysteretic force-displacement relationship, and dynamic response time history. • Seismic response of posttensioned (PT) rocking steel bridge piers is investigated through continuum and macro finite element (FE) modeling approaches. • Computationally efficient macro modeling approaches, i.e., two and multi -spring macro models, are discussed. • A procedure for calibrating the parameters of the multi-spring model using genetic algorithm is presented. • The performance of two-spring and multi-spring macro models in predicting the seismic response is examined. • Multi-spring macro model is extended to simulated the response of double rocking configuration. [ABSTRACT FROM AUTHOR]