Validation of Using Modulus of Subgrade Reaction to Consider the Soil Structure Interaction

Abstract

This paper presents the effect of the soil structure interaction on the modulus of subgrade reaction. Many of the structural designers represent the footings as a hinged support in the structural models, while the other designers represent the footings as a group of springs with spring coefficient K (kN/m). Designers assumed this modulus by different equations that are not considering the soil structure interaction. This paper showed that the soil structure interaction has a significant effect on the modulus of subgrade reaction. The subgrade reaction modulus is not uniformly distributed under the footings. Using the soil structure interaction in the calculation of the normal forces in columns results in a relatively change. Plane two-bay frames and two-bay by two-bay frames were studied using geotechnical and structural, 2D and 3D finite element programs. It is investigated for the plane frames that the normal force in the inner wall is decreased and it is increased for the outer walls. For the three dimensional frames, the inner column’s normal force is decreased and the edge column’s normal force is increased with the same normal force in the corner walls. For the complex structural systems, the distribution cannot be estimated, so that the use of geotechnical finite element programs can consider the soil, foundation, and superstructure interaction, which is highly recommended for the practical and researcher engineers.