Asymmetry of Seismic Displacement Response of Highway Bridge Supported by Spread Foundation Takeshi SHIMABUKURO* Rei FUJITA** and Norihiko YAMASHITA*** The objective of this paper is to discuss the causes of asymmetric response of superstructure using the elasto-plastic model considering the influence of P-effect and simplified periodic motion of real ground motion record. The inelastic behavior subjected to the input ground motion is so complicated that it is estimated in this paper by using the procedure to simplify the ground motion. In this study, in order to establish the simple seismic design method considering the asymmetric response. We investigate the nonlinear response characteristics using four types of nonlinear model. The superstructure itself is idealized as a single degree freedom system attached to a rigid spread foundation with two degree of freedom which is flexibly supported. As a result, simplified wave is effective to explore asymmetry of response. The response behavior and residual displacement differ with each period of models. Key Words: asymmetric response, asymmetric coefficient, P- effect, ductility factor, elasto-plastic earthquake response 1995 3 5 (3) -, (4) (1) 48 (, ) (), -,- cosφ = 1, sinφ = φ * ** ( ) mxh + c RS x + M ( φ ) mgx = mu *** G H -131-
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