Seismic Demand on Mid-Twentieth Century Reinforced Concrete Buildings Founded on Piles: Effect of Soil-Foundation-Structure-Interaction

The effect on seismic demand of the soil-foundation compliance is investigated for a reinforced concrete frame building representative of Italian constructions from the 1970s. Design accounts for regulations, materials, preferred structure and foundation layouts and analysis methods of the period. Inelastic response history analysis for multiple motions at three intensities is carried out. For the compliant-base case, each foundation is replaced with a nonlinear inertial macro-element. Results suggest that the effect of interaction is minor, lower than expected from similar analysis on a new building, due to the larger degree of conservatism associated with foundation design in the considered period and the corresponding lower strength and stiffness of the superstructure.