Torsional stiffness of arbitrarily shaped embedded foundations

A theoretical investigation of the static and dynamic torsional stiffness of arbitrarily shaped rigid foundations embedded in a homogeneous half-space, using a quadratic-element-based boundary element algorithm, is presented. Extensive parametric results are displayed in the form of dimensionless graphs for a variety of basemat shapes and a wide range of embedment depths and types of contact between the foundation sidewalls and the surrounding soil. Based on these results, simple algebraic expressions are also developed, which can be readily used by engineers in practical applications. Discussion of the results provides insight into the nature of torsional response. A numerical example illustrates the practical applicability of the developed formulas, while a companion paper studies the torsional radiation damping of embedded foundations.