Seismic response of piles supported buildings based on SFSI

This paper examines the seismic response of reinforced concrete buildings founded on pile groups. The simplest approach to account for Soil-Foundation-Structure Interaction is represented by the equivalent linear oscillator, in which the foundation behaviour is idealized by frequency dependent springs and dashpots. Such an approach is applied extensively to a case study of a 9-storey reinforced concrete building founded on piles. The seismic demand in the compliance model, expressed in terms of relative displacement, is then compared to that of the fixed base one. Finally, the prediction capability of the simplified procedure is validated against the approach based on the lumped parameters models, or LPMs, in which the foundation behaviour is idealized by a single, visco-elastic ‘macro-element’ with additional fictitious masses. It is shown that the equivalent simple oscillator is capable to predict the importance of Soil-Foundation-Structure interaction, at least from a qualitative standpoint.