Load-Carrying Capacity of Slab-on-Grade Foundations Supporting Rack Post Loads

Industrial slabs-on-grade are commonly used for warehouse facilities such as storage, retail, and distribution centers. Typical industrial floor slabs are essentially unreinforced concrete usually poured directly onto compacted subgrade. A limited number of studies have shown that the current common practice of design may be overly conservative and yields an excessively high slab thickness, which leads to a high cost of the floor slab. This study aims to experimentally investigate and verify a newly emerged design method that typically results in a smaller slab thickness and significant cost savings. Laboratory-scale slabs-on-grade were built inside a concrete-lined testing box using local soils and aggregates. A total of four 6 ft by 6 ft concrete slabs representing three different concrete mix designs and two slab thicknesses were tested under static loads that simulate storage rack post loads. Based on the limited number of tests, a preliminary finding was that the traditional design method seems to be overly conservative while the newer method may be too liberal.