Test of a Reinforced Concrete Flat Slab

The behavior of a flat slab, the second of the 5 test structures built and tested in the course of an investigation of multiple-panel reinforced concrete floor slabs, is described and analyzed. The test structure, which comprised 9 5-ft square panels, was designed essentially on the basis of the ACI Building Code (ACI 318-56). Test data included deflections at 33 locations, reinforcement strains at 335 locations, and all three components of each of the 16 column reactions. Moments computed from measured reinforcement strains were compared with the ACI design moments and indicated that the total amount of reinforcement was sufficient but was in some cases inefficiently distributed. Although the overall factor of safety of the structure was adequate, the tests clearly indicated that the service-load behavior was marginal and that excessive cracking and deflections can be expected in such structures designed for and subjected to high permanent live loads.