Post-punching capacity of flat-plate floor systems
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.
Post-punching capacity of flat-plate floor systems. In M. Sasani, S. Orton (Eds.),
American Concrete Institute, ACI Special Publication, January(SP 309),
American Concrete Institute.