Elasto-plastic Analysis of Footing Structure by the Stiffness Method with Subgrade Structure Interaction

Abstract

Analysis of footing founded on subgrade should take the compatibility of the settlements of the footing structure and that of the subgrade into account. By the conventional approach – the ‘Winkler’s spring’ method which is popularly employed in Hong Kong and other countries, the subgrade reaction is modelled by isolated springs without interaction among themselves through the subgrade. This assumption actually contradicts the theory of elasticity as well as the continuum mechanism. Various researches have therefore been conducted to establish relations among the springs so as to simulate their ‘interactions’. However, these approaches were often approximate ones and may require calibration against results of exact analysis. In this paper, a refined analysis is formulated where the relations between loads and settlements of subgrade are based on the Boussinesq or Mindlin equations for elastic subgrade which, though originally used to solve settlement of semi infinite elastic subgrade, can be extended to an...