Study of seismic response characteristics of building frame models using shake table test and considering soil–structure interaction

Abstract

External forces such as earthquake, wind, and blast lead to the deformation of the ground as well as of the supported structures. Ignorance of the influence of soil–structure interaction (SSI) could lead to unsafe design of structures founded particularly on soft soils. To understand the performance of a multi-storey building with varying heights, foundation types, and pile depths under the influence of SSI, a shake table test with earthquake excitation was considered necessary. In this paper, results of a series of shake table test performed on scaled multi-storey building frame models subjected to El-Centro earthquake are presented. The testing was carried out on three building frame models of four, six, and eight storeys. Acceleration, displacement, natural frequency, and damping ratio of the frame models as influenced by the following attributes have been investigated: (1) varying building heights; (2) SSI and fixed base; (3) different types of foundation systems viz. isolated, mat, and pile foundations; and (4) varying pile depths. The experimental investigations considering the SSI effects show that the natural frequency and damping ratio depend on the foundation system of the frame models. It is also observed that the natural frequency and damping ratio decrease with the increase in height of frame model. The investigations show that the pile foundation offers least lateral displacement of the frame models as compared to the isolated and the mat foundations. Empirical formulas are extracted from the test results to estimate the damping.