Aruna Karunarathne

Expansive soils continue to be one of the most difficult and costly ground conditions faced in residential construction. Their shrink-swell behaviour causes differential ground movement, leading to widespread serviceability issues. Numerous international design standards and methods have been developed to mitigate these effects; however, their predictive consistency and underlying assumptions remain insufficiently evaluated. This study presents a critical review of residential footing design frameworks, focusing on two key aspects: the prediction of potential ground movement and the determination of footing design requirements. The review synthesises international standards, widely adopted design methods, comparative case analyses, field observations, forensic investigations, and numerical modelling studies. Results show that, although general trends in soil reactivity are consistently identified, substantial discrepancies exist in predicted footing requirements. These differences arise primarily from how ground movement is translated into structural demand rather than from variations in estimated soil response. The review further examines the treatment of climate and moisture effects, demonstrating that vegetation, drainage, and construction-induced variability significantly influence performance but are inadequately represented in current frameworks. The study highlights the potential benefit of performance-based, climate-responsive design approaches that integrate improved soil characterisation with coupled numerical modelling to enhance reliability and consistency in residential footing design.

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.