Post-Punching Capacity of Flat-Plate Floor Systems

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Title: Post-Punching Capacity of Flat-Plate Floor Systems

Author(s): Sarah Orton, Zhonghua Peng, and Ying Tian

Publication: Special Publication

Volume: 309

Issue:

Appears on pages(s): 1-12

Keywords: post-punching, punching shear, flat plate, integrity reinforcement, anchorage, reinforcement ratio

Date: 6/1/2016

Abstract:
In the case of a punching shear failure of a slab-column connection, a certain degree of resistance to a progressive collapse in a flat-plate structure can be provided by post-punching capacity. Understanding the behavior of slab-column connections after punching shear failure is critical to understanding if the post-punching capacity could be used to limit the progression of collapse in flat-plate structures. This paper presents test results of eight isolated slab-column specimens with three main variables to investigate post-punching capacity: tensile reinforcement ratio, anchorage of tensile reinforcement, and static or dynamic loading. The results showed that post-punching capacity in slab-column connections with discontinuous compressive reinforcement and no anchorage of the tensile reinforcement was on average 53% of the punching load in static tests. However, this capacity existed only immediately after a punching failure and the residual capacity quickly dropped off as the reinforcing bars were ripped out of slab concrete. If the tensile reinforcing bars were anchored into slab, the post-punching capacity reached 80% of punching capacity with an increasing post-punching capacity with displacement until tensile rupture of the top reinforcement.