Abstract:Because of the uncertainty of the time, location and magnitude of the next earthquake, it seems necessary to specify the seismic performance of bridges beyond the two levels of seismic intensities used in most of the seismic design codes. It’s suggested in this paper that collapse of piers and unseating of girders should be prevented even under earthquakes beyond the two levels of seismic intensities, and seismic performance requirements of a new seismic design method is presented for three levels of seismic intensities. A multi-defense aseismic spherical (MDAS) bearing is used to trigger each seismic defense and change the bridge structure adaptively. The configuration and working mechanism of MDAS bearings are introduced firstly in this paper, the results of mechanical properties test of an MDAS bearing are presented, and it’s shown that the design requirements are all satisfied and the seismic isolation performance of the bearing is effective and reliable.
