Flat plate systems, where slabs are directly supported by columns without the intermediary of beams, offer reduced storey heights and additional usable space. However, these beamless configurations are susceptible to high localised shear stresses at the slab-column joints, rendering them vulnerable to brittle punching shear failures. Such failures can lead to the redistribution of loads to adjacent joints, potentially triggering a chain reaction that culminates in disproportionate progressive collapse.

Despite comprehensive research aimed at preventing the progressive collapse of flat plate structures through experimental, numerical, and theoretical studies, significant knowledge gaps persist. Predominantly, existing research has centred on static loading scenarios, neglecting the substantial dynamic responses during actual collapse incidents. While some studies have considered dynamic effects, they primarily examine structural behaviour under design load conditions, with limited exploration of responses in ultimate states. Furthermore, the commonly used research methodology, the alternative path (AP) method, assesses structural integrity after column removal. Although suitable for RC frame structures, this method may not fully capture the vulnerabilities unique to RC flat plate structures, especially those related to punching shear damage at the slab-column joints caused by slab overloading-a primary trigger for progressive collapse. Moreover, the application of dynamic increase factors (DIFs) in analyses, as recommended by the DoD and GSA guidelines, is considered overly conservative for flat plate structures.

To fill the research gaps outlined above, this PhD investigation undertakes a series of experimental tests on reinforced concrete (RC) flat plate substructures, focusing on scenarios of both column failure (CF), as widely considered, and slab-column joint failure (JF), not being thoroughly considered so far. For the CF series, the study evaluated the dynamic collapse resistance of a specimen following the instantaneous removal of an interior column under varying gravity loads. The JF series commenced with a conventional push-down test to determine collapse resistance under quasi-static conditions. A subsequent test in the JF series more closely resembled real-world collapse scenarios by incrementally applying gravity loads without further intervention, effectively replicating the spontaneous failure conditions and dynamic effects inherent to flat plate structures. Enhanced by further numerical modelling and theoretical analysis, this research provides profound insights into the mechanisms of collapse resistance, patterns of load redistribution, and the impacts of dynamic effects on RC flat plate structures.