Progressive collapse research of concrete flat plate structures, typically investigated through the alternate path (AP) method with a focus on column failure (removal), has often neglected the facts of real-life collapse events which are caused by slab overloading, leading to initial punching shear failure at slab-column joints. Progressive collapse of the structural systems triggered by slab-column joint failures exhibits distinct failure modes and resistance mechanisms from those triggered by column failures. Building upon our initial tests on the overloaded slab specimen under quasi-static loading regimes, this paper presents an innovative experimental study that closely mirrors the load-resistant mechanisms of the most common collapse incidents in flat plate structure systems in the real world. By successively stacking up gravity loads without additional interventions, the test accurately simulates the spontaneous failure conditions typical of flat plate structures. A key discovery of this research is the identification of a unique reversing load redistribution mechanism, a phenomenon not previously observed in our slab overloading tests or in studies focused on column removal scenarios. This discovery highlights the necessity of enhancing the post-punching capacity at the slab-column joints as a critical factor in preventing collapses due to slab overloading. In addition, this study provides an in-depth examination of the dynamic effects inherent in the progressive collapse of flat plate structures. Evaluating the dynamic increase factor and load amplification factor offers supplementary data pertinent to real-world collapses, providing essential insights for improving the resilience of flat plate structures against initial joint failure due to slab overloading.