A hybrid precast concrete stiffened wall substructure for residential construction on expansive soils

The use of precast systems reduces material wastage, decreases effect of weather impacts, cuts down unexpected costs, lessens skilled labour dependence and minimises construction hazards. However, the full potential of precast construction is yet to be realised in part due to most advancements being focused on its superstructure. Development of precast substructures or foundation systems for lightweight buildings, such as residential structures, needs to consider functionality and susceptibility to damage induced by the swelling movement of expansive soils causing significant structural damage and financial loss. Due to this, the main objective of this paper is to assess the ultimate strength and serviceability of a developed precast concrete wall substructure using full-scale laboratory testing and coupled finite element modelling, respectively. This study evaluates a developed hybrid precast concrete stiffened wall substructure using laboratory experiments and numerical simulations to determine its ultimate strength and serviceability, respectively. The innovative design of the developed precast substructure satisfied functional requirements for residential construction application. The slab and rib portions of the developed substructure had an acceptable ultimate strength with failure observed at 4.5 times the factored load equivalent and 2.6 times the factored load equivalent, respectively. Moreover, the developed precast system due to its configuration had reduced the active depth of expansive soils prone to moisture changes, the vertical soil movement around the prefabricated footing, and the deformation experienced by the system. •Failure was observed at 4.5 times and 2.6 times the factored load equivalent for the rib and slab portions of the prefabricated concrete slab-wall substructure.•Soil excavation reduced the expansive soil movement, however, made the substructure susceptible to lateral earth pressure due to swelling.•Soil-structure simulation determined the most critical area is at the corner for both slabs and ribs portions of the precast system.•The ribs are carrying the majority of the loads applied by the expanding soil and the above storey.