Pounding reduction of highway bridges with pounding effect by using magnetorheological dampers under earthquake excitations

Seismic pounding between the adjacent segments of the multi-span concrete highway bridges can result, significant structural damage. The aim of this paper is to investigate the possibility of using magnetorheological (MR) dampers to reduce the collision between the adjacent segments of the highway bridges in severe seismic events. The analysis of this study is focused on the highway bridges with base-isolated rubber bearings. The nonlinear equation of dynamic equilibrium of the structures is first established, considering the pounding effect of the bridges under earthquake excitations. As a basis for the design of the semi-active control system, an active control system is developed by employing the instantaneous optimal control algorithm to determine the active control forces of the actuators. The MR dampers of the semi-active control system, are designed to trace the instantaneous optimal control forces for manipulating the dampers. The control algorithm is then modified to incorporate the time delay effect of the control system based on predictive control algorithm. A highway bridge with five segments is analyzed by using the proposed method. The results show that the semi-active control system can effectively reduce the structural pounding of the highway bridges under earthquake excitations if the semi-active control system is appropriately designed.