After punching failure in a slab-column connection, the possibility of progressive collapse in four buildings in reinforced concrete was analyzed using the structural analysis software SAP2000 considering the Finite Element Analysis and the structural design computational program Eberick. The flexural capacity of the failed floor was also verified using the Yield Line Theory, taking into account the contribution of the reinforcement in the slab.

Considering the failure of a support, there is a redistribution of reactions in the columns of the structure, and a new verification of the punching was carried out in the most overloaded connections according to the standards NBR 6118:2014, EUROCODE 2:2004 and ACI 318:2019. In this study, the damaged connections have zero or partial residual strength.

A well-anchored integrity reinforcement was placed at the bottom of the supports in order to resist inversions of bending moments after local damage, also to guarantee a partial residual strength as well as an attempt to avoid new failures and accidents with the loss of countless lives. Integrity reinforcement steel areas were calculated and compared according to NBR 6118:2014, GSA:2013 and CEB:2010 codes and the most conservative code was found.

By considering the presence of integrity reinforcement and punching failure in the existing P6 connection in the first example, the ACI 318 and NBR 6118 codes indicate that the most overloaded connections do not fail and are able to withstand the new load redistribution configuration. In the second construction, assuming complete punching failure at P16, new damage does not propagate in the structure according to the three codes. In the third and fourth example, the structure is very susceptible to progressive collapse according to the standard EUROCODE, since the punching failure has propagated in the most overload connections.

After the punching failure of a slab-column connection in the first and fourth buildings, the flat slab does not present satisfactory flexural strength because the collapse load was lower than the expected load to act on the floor according to the Yield Line Theory.