Seismic response of a coupled wall-frame structure considering soil-pile-structure interaction

In this paper the effects of Soil-Structure Interaction on the seismic response of coupled wall-frame systems on pile foundations are investigated accounting for the superstructure nonlinearity. According to the substructure approach, the kinematic interaction analysis is performed in the frequency domain, by means of a numerical procedure proposed by the authors, obtaining the dynamic impedance matrices of the soil-foundation systems and the Foundation Input Motions. The nonlinear inertial interaction analysis is performed in the time domain adopting a classical finite element formulation where suitable Lumped Parameter Models are introduced to account for the frequency-dependent behaviour of the soil-foundation system. SSI effects are evaluated, with reference to a 6-storey 4-bay wall-frame structure, comparing the results with those obtained from classical fixed base analyses. SSI effects on structural displacements, base shear, ductility demand and evolution of dissipative mechanisms are shown and discussed.