Abstract

Foundations perform a crucial role in structures to transmit the loads from the superstructure to the soil beneath. The first utilization of shells as foundations was about six decades ago in Mexico. Shells are structures that transmit loads based on their form rather than mass, allowing to preserve more material. Investigations illustrated that the shell foundations provide higher bearing capacity and better settlement characteristics relative to traditional flat footings. In order to improve the geotechnical behavior of shell foundations, researchers attempt to obtain the optimum shape of shell footings by achieving more uniform stress distributions beneath the soil.
This thesis scrutinizes the stress distributions below embedded triangular shell strip footings resting on loose, medium, and dense sands by examining the effect of the edge angle. A series of two-dimensional numerical models are developed and calibrated with conducted experimental results in the literature. Mohr-Coulomb failure yield criteria are employed to simulate the soils with elastic-perfectly plastic behavior. Also, plane strain conditions are assumed to model the soils. The results indicate an increase in average stress distributions below the shell foundations by reducing the edge angle under a particular applied load. Triangular shell foundations demonstrate higher load-carrying capacity and more uniform stress distributions beneath the soil than flat foundations. Contact pressure at the soil-foundation interface and stress distributions at different depths are attained and presented. This study reveals that the optimum edge angle for triangular strip shell foundations in loose, medium, and dense sand states is 55 degrees.