Stiffness of Rigid Foundations Resting on Layered Soil

Abstract

Soil-structure interaction (SSI) studies have been conducted for many decades, where several studies showed the importance of including SSI in static and dynamic analyses of structures. Unfortunately, design engineers don't account for SSI in their routine analysis of different structures; this is partially due to the Jack of closed form solutions for foundation stiffuess constants, particularly for rigid footings resting on layered soils.

This study presents a general review of SSI techniques. It also provides useful charts for evaluation of static stiffuess of rigid footings together with numerical examples.

A computer program was developed using Fortran 90 language, to evaluate vertical and rocking stiffuess constants of rigid footings resting on three different soil deposits that are often met in practice: I) half space; 2) stratum; and 3) layered soil profiles. A group of charts was produced to facilitate determination of foundation stiffuess constants.

The results of the developed program were verified, by comparison with those of other approaches.

As an application, undamped free vibration analysis of skeletal structures was made with foundation stiffuess constants obtained using the proposed approach.