NON-LINEAR ANALYSIS OF SOIL-PILE-STRUCTURE INTERACTION UNDER SEISMIC LOADS

The seismic response of structures supported on a pile foundation is extremely complex, since the soil behavior is non-linear and liquefaction may occur during earthquakes. The soil-pile-structure interaction becomes extremely important for seismic analysis and design, so that this topic has been studied widely. In this study, an approximate and practical method is described for the seismic analysis. Two commercial software packages are used for considering the nonlinear soil-pile-structure interaction. Stiffness and damping of the pile foundation are generated from a computer program DYNAN, and then input into a finite element model by SAP2000 program. The seismic response of a vacuum tower structure supported on pile foundation is examined in a high seismic zone, including response spectrum analysis and time history analysis. The vacuum tower with weight of 5,600 kN and height of 35 m set on a steel frame. To illustrate the effects of soil-pile-structure interaction on the seismic response of structure, three different base conditions are considered, rigid base, i.e. no deformation of the foundation; linear soil-pile system; and nonlinear soil-pile system. The case of pile foundation with liquefaction of sand layer is discussed. The method and procedure introduced can be applied to the design of tall buildings, bridges, industrial structures and offshore platforms with soil-pile-structure interaction under seismic, blast, sea wave and other dynamic loads.