Soil-pile-structure interaction in the seismic response of coupled wall-frame structures

ABSTRACT The aim of this paper is to study the effects of soil-structure interaction on the seismic response of coupled wall-frame structures on pile foundations considering the non-linear behaviour of the superstructure. According to the substructure method, the kinematic interaction analysis is performed by means of a numerical procedure obtaining the dynamic impedance functions and the foundation input motion both necessary to perform inertial interaction analysis. A suitable lumped parameter model is defined to reproduce in the time domain the frequency-dependent impedances of the soil-foundation system. The vertical, horizontal and rotational components of the soil-foundation impedance functions, as well as the roto-translational coupling one, are taken into account. The non-linear inertial interaction analysis is performed by using a finite element model of the superstructure. With reference to a 6-storey 4-bay wall-frame structure, designed according to the Displacement-Based Design and founded on a soft soil deposit, comparisons are made between the compliance base and the fixed base models. The effects of the soil-structure interaction, in terms of structural displacements, base shear, ductility demand and evolution of dissipative mechanisms, are evaluated.