INFLUENCE OF KINEMATIC SOIL – STRUCTURE INTERACTION ON THE SEISMIC BEHAVIOUR OF REINFORCED – CONCRETE FRAME BUILDINGS

In earthquake-prone areas, soil–structure interaction (SSI) may play a key role in ensuring structural safety. This study investigates the effects of SSI on the seismic response of a six-storey reinforced concrete (RC) frame building, using guidelines from American codes and Eurocode 8 for soil types B and C. The analysis compares the building's behavior under various soil conditions and foundation embedment configurations. To accurately assess these effects, four models were analyzed: a fixed base model, a flexible base model, a model incorporating soil conditions beneath the foundation and on the basement walls to simulate the effects of embedment, and a model with reduced spectral acceleration due to the kinematic SSI effects. A linear-elastic analysis was conducted for all models to evaluate the structural response in terms of base shear forces, storey moments, storey displacements, and inter-storey drifts. The results show that SSI lengthens the period of the structure, which affects the values of the base shear forces. SSI generally reduces the base shear forces, but in case of very stiff structures it may increase its values. In any case, the inclusion of SSI leads to an increase in storey displacements and inter-storey drifts, particularly in models with flexible foundations and embedded basements, due to the release of rotations on the foundation level. The model with reduced spectral acceleration due to kinematic SSI effects demonstrated how the kinematic soil – structure interaction effects influence the overall seismic response of the structure. These findings highlight the importance of accounting for SSI in the structural design of buildings located in seismic regions, as neglecting these interactions can lead to an underestimation of critical design parameters such as shear forces, moments, and displacements. Incorporating SSI effects ensures more accurate seismic performance predictions and enhances the resilience of structures in earthquake-prone areas.