Concrete Bearing Capacity around Large Inserts

Concrete bearing stress test results on large embedded inserts subjected to shear failure loads are presented. Tests were performed on eight individual inserts that were cast into a prototype concrete slab reinforced similarly to the concrete floor slab in the Gas Centrifuge Enrichment Plant (GCEP) at Piketon, Ohio. Analyses were made to examine the rigidity of the insert as a beam on an elastic foundation. These analyses, which agreed with field measurements, indicate that an insert rotates as a rigid body. With this knowledge and assuming that the ACI rectangular stress block exists in front of the insert, the maximum bearing stress is computed and compared to fc′. The results indicate that the average bearing stress on the concrete at the failure load is 3.78fc′.