Soil-structure interaction effects on tall buildings with mat foundation

Abstract

Finite element analysis is performed to study soil-structure interaction (SST) effects on static and seismic response of tall buildings on mat foundations. Simplified numerical models consisting of beam-column elements and lumped masses are used to model building superstructure including mat. For the static analysis the soil is represented by equivalent springs lumped at the foundation nodes. Results from the static analysis show that the mat can be modelled realistically with beam-column elements to represent the thick slabs. It is also found that the superstructure rigidity has some effects on the overall settlements and bending moments in the mat. For seismic analysis, the soil is modelled by frequency independent spnngs with viscous damping. Two and three-dimensional models for different building layouts are used. Building height is varied from six to ten stories. The influence of soil flexibility on the response of the mat and the superstructure is studied. Parametric studies are performed to evaluate the effects of different parameters on the behaviour of the building. It is observed that soil-structure interaction, in general, results in reduced base shear under seismic loading. SSTeffects not only depend on building configuration, but also are very much influenced by ground motion characteristics. SST effects are also found to be beneficial for building with mass eccentricity where torsional response is important.