Finite element method analysis of slabs on elastic half space expansive soil foundations

A finite element computer program has been developed to analyze slabs on elastic half space expansive as well as compressible soils. Mindlin orthotropic plate theory is adopted for structural analysis of ribbed or constant thickness slabs. The foundation soil is assumed to be an isotropic, homogeneous, and elastic half space. The behavior of an elastic half space is calculated by dividing the surface of the elastic half space into rectangular regions. These regions are represented by stiffness matrices and they are assembled onto the rectangular plate finite elements.; The shape of the soil surface underneath the slab is described by the differential soil movement (y_m) and edge moisture variation distance (e_m). The mounded soil surface requires an iterative procedure in the computer program for this soil-structure interaction system. The program calculates displacements, moments in x- and y-directions, twisting moments, and shear forces. The comparisons of the results with the Post Tensioning Institute's (PTI) Design and Construction of Post-Tensioned Slabs-on-Ground manual examples show that the PTI analysis is conservative for the center lift case, but is not conservative for the edge lift case.