Flexure-induced punching of concrete flat plates

摘要

Local yielding of the top flexural reinforcement above a column can induce punching failure. Slabs supported directly on columns without beams or shear capitals (flat plates) are vulnerable to flexure-induced punching failure when the amount of the flexural reinforcement above the column is not adequate. Provisions of ACI 318-14 and CSA A23.3-14 give the value of the nominal shear strength as function of specified concrete strength, geometry of slab and column and the shear reinforcement. The present research specifies the minimum amount and layout of flexural reinforcement that takes flexure-induced punching into account. These requirements are satisfied in current code design for many practical cases. A code change is proposed to cover all cases.