An experimental study on post-punching behavior of flat slabs to prevent progressive collapse

Document Type : Research Article


Department of Civil Engineering, Ferdowsi University of Mashhad, Mashhad, Iran


If unpredictable loads are applied to the flat slab-column connections, punching shear 
failure occurs with almost no warning signs. According to the brittle manner of this failure, the load 
carried by the slab-column connection redistributes to adjacent supports and causes overloading to these 
supports. Due to this overloading and brittle nature of punching shear failure, progressive collapse may 
happen both horizontally or vertically. In order to prevent the progressive collapse of flat slab-column 
connections, it is necessary to provide a secondary load carrying mechanism after punching shear. In this 
Paper, Suggestions for establishing a supporting mechanism in the flat slab connections after punching 
failure are proposed. For this purpose, an experimental study was performed to investigate the postpunching behavior of 9 slab specimens with various reinforcement layouts and concrete covers. The 
effects of integrity, compressive and bent-up reinforcements, diameter of tensile reinforcements, and 
concrete cover of tensile reinforcements on the post-punching behavior of slab-column connections were 
studied. The results of the experiments show that the integrity reinforcements significantly improve the 
post-punching strength. The compressive reinforcements may not increase post-punching strength. The 
increase of the concrete cover of the tensile reinforcements and decrease of the diameter of the tensile 
reinforcement result in an increase of the post-punching strength. The bent-up reinforcement increases 
the punching and post-punching strengths, simultaneously.


Main Subjects

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