ABSTRACT
During an earthquake, the soil beneath the footing of a structure can deform plastically. With this nonlinear Structure-Foundation-Soil Interaction (SFSI), the response of the structure will be different from that with an assumed fixed base. Previous study of structural response with SFSI considered only the horizontal earthquake excitations. The effect of vertical component of the excitation has not been well understood. In this study a shake table test was conducted on a 1:4 scale structure model to reveal the structural response with SFSI when subjected simultaneously to horizontal and vertical excitations. To simulate the effect of SFSI the structure was placed on sand in a rigid box. The excitation used was ground acceleration recorded during the 1995 Kobe earthquake. The result showed that when only horizontal excitation was considered, the acceleration of the structure with SFSI was smaller than that with a fixed base. However, when vertical excitation was considered, the vertical acceleration of the structure with SFSI was larger than that of the structure with a fixed base.
