Seismic behavior of cable-stayed bridges under strong ground motions

Seismic behavior analysis of the long-span cable-stayed bridge is a complex process involving different uncertainties. This paper performs a sensitivity analysis of cable-stayed bridges using the finite element method on Midas/Civil. They include different types of ground motions scaled to different peak ground acceleration (PGA) levels, the effect of the multi-support excitations due to time-lag propagation or nonsynchronous excitations, and the effect of the angle of the incidence of the earthquake is determined. To evaluate the optimum initial cable prestress forces in cables unknown load factors method is used. The response quantities of interest include the displacement of the tower and deck, variation in prestress force in cables, torsional in the deck, shear force, and bending moment at the supports. Results show that the effect of the PGA variation and angle of incidence of the earthquake is moderate. In contrast, the synchronous and nonsynchronous seismic excitation effect on the response quantities is significant.