Interaction analysis of waffle slabs supporting houses on expansive soil

Abstract This study investigates the soil–slab interaction for waffle slabs supporting residential structures on highly expansive soils. Interaction modelling techniques are reviewed, and the implications of the modelling assumptions typically employed are discussed. More realistic modelling assumptions are proposed, and their effects are investigated. For this purpose, advanced incremental/inelastic FE models are developed in OpenSees to capture the slab structural response during the history of soil movement in heave condition. Soil profile (mound shape), soil stiffness profile and soil–slab contact are updated corresponding to growing mound. The study provides an insight into the resulting changes in bending moment and deformation demands on such slabs. It is found that the conventional assumption of a constant soft soil stiffness coupled with a stepped transition to that of hard soil is generally unconservative. The analyses also suggest that predefining a critical scenario and disregarding the history of loading is not necessarily conservative.