Shaking Table Tests on Dynamic Characteristics of Pile-Soil-High Rise Structure System on Soft Soil Foundation

Abstract:

Shaking table tests are designed and performed on high-rise frame structures considering pile-soil dynamic interaction system and a frame structure model on fixed-base condition with the 1：6 scaling factor in this paper to study the influence mechanism of pile-soil interaction on the dynamic characteristics of high-rise structures on soft soil foundation. The layered shear box is used to simulate the boundary of soil. The mixture of sawdust and sand is adopted as the foundation soil， and the superstructure is a 12-story reinforced concrete frame structure. The foundation adopts the 3 × 3 pile group foundation. By comparing the structural dynamic characteristics of the soil structure interaction （SSI） frame model and the fixed-base model， the influence law of the SSI effect on the high-rise frame structure in this test is summarized. The soil has a significant filtering effect on ground motion. It mainly amplifies the vibration near the fundamental frequency of the soil， and the amplification amplitude decreases with the strengthening of ground motion. The soil amplifies the peak acceleration in minor earthquakes and reduces the peak acceleration in major earthquakes. The frequency of the structure in the SSI system decreases and the damping ratio increases. The structural damage in the SSI system appears later and develops more slowly than that of the fixed-base structure. At the frequency of soil， the vibration mode of SSI system is significantly affected by the soil， and its vibration mode amplitude distribution is obviously different from that of the fixed-base structure. The vibration mode of the SSI system far away from the soil frequency is consistent with that of the fixed-base model.

Key words:soil-structure interaction;dynamic characteristics;shaking table test;tall building;soft soil