Through　quasi-static　loading　regimes,　notable　research　efforts　have　been　made　in　recent　years　towards　understanding　the　structural　behaviour　and　resistance　mechanism　of　reinforced　concrete　(RC)　flat　plate　structures　against　progressive　collapse　events.　Nevertheless,　dynamic　responses,　being　an　inherent　nature　of　any　progressive　collapse,　were　unable　to　be　adequately　studied　in　these　quasi-static　studies.　Moreover,　fewer　studies　were　performed　on　flat　plate　structures　under　dynamic　loading　conditions,　especially　their　behaviours　under　large　deformations,　i.e.,　the　post-punching　stages.　To　fill　this　research　gap,　this　paper　presents　three　sequential　dynamic　tests　performed　on　a　1/3-scaled　2　x　2-bay　RC　flat　plate　substructure　specimen　by　instantaneously　removing　the　interior　column　under　three　levels　of　additional　gravity　loads.　In　these　tests,　the　substructure　specimen　was　able　to　withstand　the　gravity　loads　up　to　2.08　times　the　load　capacities　recommended　by　the　DoD　and　GSA　guidelines　for　nonlinear　dynamic　analyses.　The　dynamic　responses　of　the　specimen　in　the　flexural,　punching　and　post-punching　stages　were　examined　in　detail.　In　addition,　a　high-fidelity　finite　element　model　was　developed　and　validated　by　the　experimental　test　results.　The　validated　numerical　model　was　subsequently　used　to　quantify　the　dynamic　load　redistribution　patterns,　and　the　influences　of　two　loading　considerations　(i.e.,　loading　on　the　slab　overhangs　and　load　release　time)　on　the　dynamic　responses　were　also　investigated.　Finally,　the　dynamic　load　increase　effects　were　evaluated　based　on　the　analysis　model　results.　The　obtained　load-based　dynamic　increase　factors　(DIFs)　of　the　specimen　under　different　gravity　loads　were　between　1.11　and　1.46　in　the　pre-punching　(flexural)　stage,　whereas　they　were　no　more　than　1.06　in　the　post-punching　stage.