Seismic Damage Study of Asymmetric Continuous Rigid Frame Bridge Based on Nonlinear Time History Analysis

Abstract

Continuous rigid frame bridge is a common type of bridge in California, where is a seismically active areas. Main structural features of the bridge, including asymmetry, hinge structure, concretion of girder and piers affect the seismic response of the bridge significantly. In order to evaluate the safety of the bridge under earthquake, the nonlinear models of girder, limiting steels in hinge, abutment backfill, abutment bearing, pier are simulated in great detail, and a numerical dynamic overall model, composed of the above components, is made through OpenSees program. On the basis of nonlinear time history analysis with Northridge earthquake load, seismic damage of this kind of bridge is monitored. The research results acquire the accurate damage area of the bridge. Under earthquake, asymmetric continuous rigid frame bridge with curved girder tends to move to the external rim of curve. Asymmetry is detrimental to coinstantaneous vibration of frames, which can cause the large nonlinear damage of limiting steels in hinge. Due to large longitudinal relative seismic response between girder and abutment, the damage of abutment bearing and backfill could be severe. The area on the top and bottom of shorter piers in both sides of bridge is vulnerable because longitudinal steel bars in these areas are liable to yield under repeating shaking of earthquake.