Floor　systems　composed　of　beams　and　slabs　are　critical　structural　elements　of　frame　structures　to　resist　progressive　collapse.　Previous　experimental　studies　have　focused　mainly　on　beam-column　or　continuous-beam　substructures　and　have　ignored　the　influence　of　the　slab.　To　study　the　progressive　collapse-resisting　mechanisms　of　reinforced　concrete　(RC)　floor　systems,　seven　1/3-scaled　one-way　substructure　specimens,　including　five　beam-slab　specimens　and　two　continuous-beam　specimens　without　slabs,　were　tested　under　a　middle-column-removal　scenario.　The　effects　of　various　structural　parameters,　including　sectional　dimensions　(beam　height,　slab　width,　and　slab　thickness)　and　seismic　reinforcement,　on　the　progressive　collapse　resistance　were　studied　by　analyzing　material　strains　and　load-displacement　curves.　Under　small　deformations,　the　progressive　collapse　resistance　was　largely　affected　by　the　beam　height,　slab　width　and　seismic　reinforcement　in　the　beams.　However,　the　effect　of　the　slab　width,　upon　exceeding　the　effective　flange　width,　became　insignificant.　Note　that　increasing　the　slab　thickness　simultaneously　increased　the　amount　of　slab　reinforcement　according　to　the　minimum　requirement　of　reinforcement　ratio　for　slabs,　such　an　increase　will　in　turn　enhanced　the　progressive　collapse　resistance.　In　addition,　the　existence　of　the　slab　led　to　an　over-reinforced　damage　in　the　compressive　zones　of　the　beam　ends,　which　accelerated　the　bending　failure　and　the　presence　of　the　catenary　action　of　the　specimens.　Under　large　deformations,　the　progressive　collapse　resistance　was　mainly　influenced　by　the　reinforcement　area　of　the　entire　beam-slab　section.　The　total　reinforcement　area　of　a　beam-slab　substructure　designed　to　meet　a　higher　seismic　requirement　was　not　significantly　increased,　and　consequently,　the　progressive　collapse　resistance　of　the　substructure　under　the　catenary　mechanism　was　not　notably　improved.　This　finding　stands　in　stark　contrast　to　those　of　previous　tests　of　beam-column　specimens　without　slabs.　Published　by　Elsevier　Ltd.