SEISMIC RESPONSE OF BRIDGE PIERS ON ELASTOPLASTIC WINKLER FOUNDATION ALLOWED TO UPLIFT

When the bridge piers with shallow foundation are subject to intense earthquake excitations, uplift of foundations will occur and the foundation soils will enter into plashcity. It is very difficulty to simulate the uplift and yielding of supporting soils using an accurate method. An improved Winkler foundation model, which could be used to consider uplift and yield was employed in the analysis. The 1940 El Centro earthquake record was inputted to a rigid bridge pier with shallow foundation so that the nonlinear history response was obtained. It is concluded from the nonlinear analysis that the nonlinear effect is very remarkable when uplift and yielding of supporting soil are considered Compared with the linear analysis, the stiffness of bridge rier-soil system degrades in each cycle after considering uplift and yielding. The nonlinear analysis shows larger rotational response and smaller bending moment than those of the linear analysis.