EVALUATION OF SEISMIC PERFORMANCE OF LONG SPAN CONTINUOUS GIRDER BRIDGES IN REGIONS WITH IX INTENSITY

Nonlinear time history analysis method is adopted to analysis the seismic performance of long span continuous girder bridges with spans of 89, 170 and 89 in in high intensity region. Seismic isolation devices of double curvature seismic isolation bearings (DCSIB) and longitudinal dampers between abutments and main girders are adopted to reduce seismic response. Compares to other kinds of bearings, the self-restoring ability of DCSIB can prevent the displacement added in aftershock exceeding the maximum structure displacement admitted. The good hysteretic, energy-dissipation characteristic and self-restoring ability of DCSIB are considered as well as the friction energy-dissipation characteristic of sliding bearing and damping energy-dissipation characteristic of dampers, Based on above 3D dynamic model the analytical results indicate that the structure seismic response is reduced evidently after the usage of seismic isolation devices; seismic performance can basically meet the expected design goal. So it is very effective that seismic isolation devices of DCSIB and dampers can adjust dynamic characteristic, reduce seismic response, dissipate earthquake energy and guarantee the structural safety.