Analysis the effects of soil-structure interaction on the seismic behaviours of a 5-stories reinforced concrete building with basements

The paper presents analysis results of structural behaviour with and without soil-structure interaction on a five-story reinforced concrete building with basements due to seismic loads. Two numbers of basements were considered namely the building with one basement floor (M1 model) and two basement floors (M2 model). Each of the M1 and M2 model has three variations with and without the soil structure interaction namely the model with the fixed supports (MJ1 and MJ2 models), the model with solid element of the soil (MSo1 and MSo2 models), and the model with lateral soil support of spring elements (MSp1 and MSp2 models). The Soil parameters of modulus elasticity, poisons ratio, reaction modulus and spring stiffness for the MSo and MSp models were obtained from soil investigation. All six models having loads combination of gravity and earthquake loads were analysed using a finite element software package program. All loadings and design codes follow Indonesian codes. Earthquake loads were evaluated using two methods namely equivalent static loads and spectrum response analysis. The results show that the roof-floor displacements of the soil-structure interaction model (MSo and MSp) are greater 2% to 3% than to that of the non-soil-structure interaction models (MJ). The roof drift and natural fundamental period of the MSo and MSp models is greater 1% to 2% than that of the MJ model. The axial force of the columns in the MSo and MSp models is less 1% to 3% than the MJ model. The addition of basement floors to the building and modelling with soil structure interactions can minimize the roof floor displacement, the natural fundamental period of the structure, and axial force of the column by 1% to 2%.