Shaking table tests for the seismic response of a base-isolated structure with the SSI effect

To estimate the effect of the soil-structure interaction (SSI) on the seismic response of base-isolated structures, four shaking table tests were carried out. The influence of the SSI effect on the seismic response of base-isolated structures is verified and some new findings are reported. According to the tests, the damping ratios of the interaction systems with the SSI effects are larger than those of isolated structures on rigid foundations. The acceleration magnification factor (AMF) at each floor of an isolated structure is larger with an SSI effect, and the change law is also affected. With a greater PGA of input motion, AMFs increase monotonically along the height of the isolated structure with the SSI effect. The more important finding is that the rotation response of a foundation can be amplified by the isolation layer, which further reduces the isolation efficiency of the isolation layer. For non-isolated structures on soil foundations, the softer soil layer can be considered as an efficient isolation layer that reduces the seismic response of the structure.