Experimental investigation on progressive collapse resistance of precast concrete frame structures with different beam-column connections

In this paper, twelve 1/4-scale precast concrete (PC) substructural specimens with different beam-column connections under progressive collapse scenario were tested and the results were compared with that of the corresponding conventional reinforced concrete (RC) subassemblies. For assembled monolithic concrete (AMC) specimens, the top longitudinal reinforcement bars of beam passed though the beam-column joint continuously. However, the bottom longitudinal reinforcement bars of beam were either anchored as a 90° bend or lap spliced in the cast-in-place joints. Moreover, the flange effects as well as the effects of transverse beam and slab were also investigated according to spatial subassemblies with or without precast composite slabs. For fully assembled concrete (FAC) specimens, dowel bars and corbel connections, as well as steel plates and hidden corbel connections were used in the beam-column joints. Test results showed that the AMC specimens with or without precast composite flanges (slabs) exhibited almost the same progressive collapse resistance as RC specimens in the literatures, except for the peak value of the vertical load at the compressive arch action (CAA) stage for the AMC specimen with lap-splice of bottom rebars in the joints. Significant CAA at small deformation stage and subsequent tensile catenary action (TCA) at large deformation stage developed in the laminated beams under column removal scenarios. Furthermore, the transverse beam and composite slab effects could obviously increase the capacity of an AMC two-span beam. However, unlike RC specimens, CAA and TCA were not completely developed in the FAC specimens due to pull-out failure of the rebars in the beam-column joints or premature failure of the welding points between steel plates and rebars.