Study On Progressive Collapse Behavior Of RC Beam-column Substructure With A Kinked Rebar Configuration

In recent years,the research on the mechanism of building structure resisting multiple collapses has gradually become a hot area in the field of civil engineering.Reinforced concrete(RC)frame structure is one of the most widely used structural forms in the world,on which the study of single collapse mechanism is relatively sufficient currently.More and more researchers found and focused on the contradictions between seismic design and progressive collapse design of reinforced concrete(RC)frame structures,conducting some corresponding researches.Kinked rebar is a novel configuration.It can help improve the seismic collapse resistance and progressive collapse resistance of reinforced concrete(RC)frame structures without significantly increasing the cost.In this paper,the progressive collapse resistance performance of RC frame structures with kinked rebar configuration in a middle column-removal scenario was studied.The main work includes:(1)This study carried out experimental tests on the progressive collapse resistances of RC beam-column substructures with kinked rebar configuration in a middle columnremoval scenario.Nine 1/3 scale specimens were fabricated,among which two were ordinary specimens and seven were specimens with kinked rebar configuration.The parameters of the tests include: the size of the kinked rebar,the proportion of the kinked rebar,the design of the middle bars and the effect of cast-in-place slab.According to the existed experimental studies on the progressive collapse resistances of RC beam-column substructures,the loading scheme and test boundary conditions are determined.Measurement schemes for force,displacement and strain were arranged to detect the loading mechanism and internal force conversion mechanism of the specimens during the test.The load-displacement curves and failure modes of specimens with different structural parameters were obtained.(2)The development of strain in critical sections and regions of different specimens was analyzed.Based on the strain analysis and,the damage mechanism and the resistance mechanism during the progressive collapse was studied.The typical phenomena during the loading process was explained.And the influence of different parameters to anticollapse behavior was studied by comparing the load capacity and deformation capacity combined with load-displacement curve of different specimens.(3)Finite element analysis of normal RC substructure and substructures with kinked rebar was carried out,comparing with the test results.Based on the results of experimental study and the existing design methods for the bearing capacity of RC frame structures,an analyze model to determine the load capacity of RC beam-column substructures with kinked rebar configuration was proposed.The analyze model was validated by the test results which confirmed its good accuracy.