Role of the Subgrade Reaction Modulus in the Design of Foundations for Adjacent Buildings

Abstract

This paper examines the effects of soil–structure and structure–soil–structure interactions in the design of foundations for adjacent concrete buildings, which are located on soft soils. The study employs an elasto-plastic model through static (quasi-dynamic) analysis using the direct finite element method by applying earthquake loads in one time step. Two concrete buildings, one with 6 stories and another with 12 stories, were modelled and numerically analysed using ANSYS. The foundations of these two buildings were analysed separately and compared when they were assumed to be adjacent to each other. The designs of the buildings’ foundations were evaluated independently and in comparison with each other to determine the impact of these interactions. The results indicated that accounting for the effects of both interactions increases the total deformation of the foundations. Additionally, the study found that adjusting the subgrade reaction modulus values (Ks) for different sections of the foundation can be a practical method to address both interaction effects simultaneously. This method also optimizes the weight of reinforcement material (Wr) by reducing it by 15% and modifying the positions and quantities of reinforcements used and considering various subgrade reaction modulus values in foundation design.