6 - Evaluation of accuracy

Abstract

This chapter presents the evaluation of the accuracy of the strength-of-materials approach using cones. In addition, certain limitations of the procedure are established, concerning the applicable range of the embedment ratio and the shape of the axis-symmetric embedded foundation. The chapter addresses surface foundations on a multi-layered half-space and embedded cylindrical foundations. The chapter examines modeling aspects of a site with gradually varying material properties, where a large number of cone segments are required, and discusses the adequate representation of the dynamic behavior below and above the so called cutoff frequency, where an abrupt change in response occurs. The chapter addresses a cylindrical foundation embedded in an incompressible multi-layered half-space. By varying the ratio of the radii of a hemi-ellipsoid embedded in a homogeneous half-space, the accuracy for axis-symmetric foundations modeled with disks of varying radii is studied. The chapter also examines a sphere embedded in a homogeneous full-space. A homogeneous half-space and a homogeneous layer fixed at its base are addressed both for surface and embedded cylindrical foundations. In addition, mainly to demonstrate the wave propagation in cone segments, a disk embedded in a full-space and a half-space is examined. To discuss the termination criteria, a disk on the surface of a layered half-space is considered, but only for one degree of freedom. To gain confidence, a systematic evaluation of the accuracy for multiple-layered half-spaces is essential. The underlying half-space can either be flexible or rigid, in the latter case preventing wave propagation in the vertical direction toward infinity and thus radiation damping vertically from occurring. Besides the standard case where the underlying half-space is stiffer than the layers, the opposite situation is also addressed.