Punching shear failure of foundation occurs when there is a localized force acting on the structure. It is mostly found in foundations but also common in flat slabs.
In punching failure of foundations, the column breaks through the foundation mat. In flat slabs, the failure occurs at the column head. This type of failure is sudden and does not show any warning. Therefore it is crucial to check for punching shear and to provide sufficient reinforcement to take care of it. Reinforcements should be provided in addition to the main reinforcements. This punching shear must not be neglected though it is less critical than the beam shear.
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