Experimental and analytical investigation on the progressive collapse resistance of precast concrete beam-column subassemblies with connecting steel bars

The resisting mechanism of precast concrete (PC) structures against progressive collapse varies from different types of beam-column connection details. In this context, the progressive collapse resistances and the corresponding resisting capacity models for the widely adopted PC structures with additional connecting rebars is significant when extreme events frequently occurred from time to time. In this study, progressive collapse resistance of one emulative PC beam-column subassembly and two PC specimens with connecting rebars were experimentally and analytically investigated. It is found that flexural action, compressive arch action (CAA) and tensile catenary action (TCA) were sequentially developed. Compared with the emulative specimen, the specimens with connecting rebars exhibited higher CAA and TCA capacities and dissimilar failure modes by dispersing the concentrated deformations at the beam ends to other locations. To elucidate such differences, a modified CAA model considering the real stress state of reinforcements and a TCA model accounting for the tensile steel force's direction and the difference in failure mode were proposed. Experimental validation shows that the proposed models is effective to predict the CAA and TCA capacities with good accuracy. The findings in this study are beneficial to the understanding and formulation of the progressive collapse resistance of PC structures for practical engineering design.