Shallow foundation displacements using small strain soil stiffness

Foundation performance is controlled significantly by the stress-strain-strength behavior of the underlying soils which is complex. For geomaterials, the small-strain shear modulus Gmax is a fundamental stiffness applicable to both monotonic static and dynamic loading conditions under drained and undrained conditions. Yet, Gmax is too stiff for direct use in computing foundation displacements using either simple elastic analytical methods or linear elastic-plastic constitutive models contained within geotechnical finite element codes. This book develops a methodology for evaluating the performance of vertically-loaded footings using a rational framework based on the small-strain modulus, large-strain strength and strain at failure. In geotechnical practice, foundation bearing capacity is handled as a limit plasticity calculation, while footing displacements are evaluated separately via elastic continuum solutions. Herein, a hybrid approach is derived that combines these two facets into a closed-form analytical solution for vertical load-deflection- capacity based on numerical studies.