Test of a Reinforced Concrete Flat Plate

The behavior of a flat plate, the first of the five 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 nine 5-ft square panels, was designed essentially on the basis of the ACI Building Code. Test data included deflections at 33 locations, reinforcement strains at 294 locations, and all three components of each of the column reactions. Comparisons of the moments measured in the critical sections of the test structure with the ACI design moments indicated that the total extent of flexural reinforcement provided by the design method in the entire structure was not deficient but that the distribution specified was inefficient. The overall behavior of the test structure was satisfactory at all levels of loading as was the measured over-all load factor of 2.3. However, collapse was caused by punching through of one of the interior columns. The flexural strength of the slab was higher than the load that could be transmitted from the slab to the interior columns.