Optimal design of friction tuned mass damper for seismic control of an integral bridge

Vibration control systems such as tuned mass damper (TMD) have drawn considerable attention due to their ability to reduce the seismic response of structures and the consequent damage. The present paper investigates the performance of a new type of TMD, called the friction tuned mass damper (FTMD), in decreasing the seismic response of a four-span integral bridge. The performance of the FTMD in then compared with the TMD under various conditions. The parameters of both dampers are computed via an optimization method. The bridge with damper is then subjected to several strong earthquakes in the transverse direction in different intensity levels, ranging from 0.2 g to 0.8 g. The Particle swarm optimization with passive congregation (PSOPC) is employed and carried out in MATLAB, while the structural modeling and nonlinear dynamic analysis of the bridge is programmed in OpenSees. Numerical results indicate that the FTMD performs better than the TMD in reducing the displacement of the deck. At low intensity of 0.2 g, the reduction in the displacement response of the deck by the TMD and the FTMD are about 28% and 40%, respectively. These values reach 8% and 15% at intensity of 0.8 g. Therefore higher earthquake intensity significantly undermines the performance of both dampers. However the superior performance of the FTMD compared to the TMD is observed.