Experimental study on soil-structure interaction of steel frame under seismic excitations

Abstract

Three types of shaking table tests were carried out to investigate the soil-structure interaction (SSI) effects on the seismic performance of the steel frames resting on soft soil ground. Three different models were involved in the shaking table tests including a ten-story steel frame resting on a soft soil ground, a ten-story steel frame resting on a rigid ground, and a free field with soft soil, respectively. First, the characteristics of soils were studied to choose suitable soft soil for the tests. Then, a laminar shear soil box was developed to contain soft soil and simulate the soil in the free field. Finally, the three models were subjected to various intensity seismic excitations of the El-Centro earthquake, the Kobe earthquake, and the Taft earthquake. The results showed that SSI effects noticeably affect the propagation of seismic waves, the dynamic characteristics, and the dynamic responses of the steel frame. For the steel frame resting on the rigid ground, the fundamental frequency of the SSI system decreased, but the damping ratio increased. The peak acceleration of the steel frame decreased when rested on the soft soil ground, but the inter-story drift increased. Consequently, the seismic SSI has a complicated influence on the dynamic responses of steel frames and should be considered reasonably to provide a rational seismic design for steel frames resting on soft soils.