Symmetric punching of reinforced concrete slabs

Synopsis The paper reports punching tests on 28 reinforced concrete slabs. The tests were divided into five series primarily concerned with the effects of the arrangement of flexural reinforcement, absolute size or depth, concrete strength and ratio of reinforcement, boundary restraint and the size of the loaded area. The results are compared with the predictions of four Codes of Practice-BS 8110, CP 110, ACI 318-83 and the CEB-FIP Model Code. In regard to BS 8110 it is demonstrated that the Code generally gives a small scatter of the ratio of calculated and experimental strengths, although its method of defining the ratio of flexural reinforcement is inferior to that of CP 110. It is also shown that BS 8110 does not achieve the level of safety intended in the definition of characteristic strength. If the ddefinition of the ratio of reinforcement were improved, the intended level of safety could be attained by a 10% reduction in either the basic shear stress or the size factor ξ S .