RESIDUAL SEISMIC PERFORMANCE OF RC PIERS AFTER BEING SUBJECTED TO RANDOM AND PULSIVE LOADING HISTORY EQUIVALENT TO SEISMIC RESPONSE

Abstract

 The authors have examined the residual seismic performance of RC piers through cyclic loading experiments, referencing the limit state defined in the Highway Bridge Specifications. A dynamic earthquake response analysis was conducted on the test specimen by reducing its stiffness using the proposed formula. Additionally, a static earthquake response experiment was performed, in which the obtained response displacement was applied to the actual test specimen at a constant speed. The purpose of this experiment is to investigate whether the proposed formula for predicting equivalent stiffness can be applied to earthquake responses that exhibit greater variation in the balance of positive and negative amplitude displacements and the number of repetitions compared to the alternating cyclic loading experiments, as well as to assess the applicability of the proposed formula in dynamic earthquake response analysis. The findings from the static earthquake response experiment are reported. Furthermore, since the response displacement when the stiffness is reduced using the proposed formula may exceed twice that of the unmodified stiffness, the calculation formula proposed in this study facilitates an examination in accordance with anti-catastrophe considerations, taking into account multiple earthquake actions in the seismic performance verification based on the skeleton curve of the load-displacement relationship of RC piers. The reduction rate of equivalent stiffness for the second loading in this experiment, compared to the first loading, was generally consistent with the reduction rate of equivalent stiffness calculated using the authors' proposed formula. This indicates that the model of the skeleton curve of the load-displacement relationship based on this formula is valid within a certain range, even under random and pulsive loading histories.