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.