Effect of loss of bond on flat-slab building collapses.

Between 1997 and 2010, there was a small, yet unexpected, number of flat-slab car park buildings that collapsed under service loading. In all the cases, the collapse was preceded by loss of bond (LoB) between the concrete and flexural reinforcement. All investigations of the causes of these collapses have since been inconclusive, particularly as regards the effect of LoB. Yet, LoB due to yielding of the flexural reinforcement in tension had already been proposed as the main cause of punching, and failure criteria derived on the basis of this proposal were found to produce predictions that correlated closely with experimentally established values of the punching failure load. The aim of the present work was to extend the range of application of these criteria to the case of LoB due to steel corrosion and test their validity against the available information on the car park building collapses. [ABSTRACT FROM AUTHOR]