Punching shear is a special failure type when the reinforced concrete slabs subjected to high localized forces. When the flat slab structure is in question the punching shear occurs at column support points. The failure is due to shear. The failure like this is catastrophic because the there are no visible signs shown prior the failure. Punching shear failure disasters have occurred several times in the past decade.  An example of this kind of failure is shown in the images.

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