Macro modeling of slab-column connections in progressive collapse with post-punching effect

In this paper, macro-modeling methods of the slab-column connections were suggested to predict their post-punching behavior. These modeling techniques can be used to evaluate the potential for progressive collapse of flat slab buildings. It is acknowledged that structural damage is primarily focused on the flat slabs at their slab-column connections. In the suggested model, shell elements were used to simulate the plate and beam connector components to simulate punching failure. Six load-deformation curves were implemented with linear and nonlinear behaviors to simulate bending, shear, torsion, and axial force of the beam connector components to model the inner forces transfer between the slab and the column and to study the action of the connections. Two methods of macro modeling for simulating post-punching behavior were presented: rebar-modeling, link element modeling. The rebar or link element is placed vicinity to the connector beam element and activated after the punching failure. A bilinear load-deformation curve for the link element is defined to simulate post-punching behavior. Some of the parameters used to introduce these curves are calibrated with the test results. Test specimens validated the proposed methods. The results show that both post-punching behavior modeling techniques have acceptable accuracy in predicting post-punching strength, post-punching stiffness, and deformation capacity.