Real‐time hybrid simulation for investigating the influence of vertical ground motions on the lateral response of RC piers

Abstract

AbstractThe vertical component of ground motions can affect the seismic performance of reinforced concrete (RC) piers as significant as its horizontal counterpart. However, real‐time testing for RC piers subjected to both horizontal and vertical ground motions has been scarcely conducted due to the difficulty in multi‐axial control of actuators. In this study, the seismic response of a bridge RC pier was investigated by conducting real‐time hybrid simulation (RTHS), where the RC pier was physically tested in the laboratory and the bridge superstructure was numerically modeled. The test setup that can synchronously apply both horizontal and vertical ground motions was constructed by using three dynamic actuators and a flexible loading beam (FLB). The lateral response of the RC pier was investigated by varying the intensities for vertical ground motions, while the same intensity for horizontal ground motion is used. It was found that the axial force from the dead load of superstructure can significantly affect the initial stiffness, strength, and post‐yield response of the RC pier. For the selected earthquake ground motions, however, the intensity of vertical ground motion did not make a substantial difference in the lateral response, although there was a notable difference in the fracture pattern.