Experimental test on progressive collapse resistance of the spatial behavior#br#
of integrated precast concrete frame substructures
Zhang Wangxi1,2 Wu Hao1 Zhang Jinyi3 Wang Xiong1 Yi Weijian1,2
1. College of Civil Engineering College, Hunan University, Changsha 410082, China;2. Key Laboratory of Building Safety and Energy Efficiency of the Ministry of Education, Hunan University, Changsha 410082, China;3. Hunan University of Science and Technology, Xiangtan 411201, China
In this study, three specimens of two-third scale integrated precast concrete (PC) structures with slotted and lapped splicing of beam-column joints were tested. The first one was the spatial frame substructure, the second one was the planar frame substructure, and the last one was the cantilever structure. The quasistatic loading tests with the force-displacement control were applied to the mid-column. According to the structural performance including the load-carrying capacity, deformation capacity, crack distribution, rebar strain and failure mode, the progressive collapse resistance mechanism of the specimens was analyzed. The test results showed that before the peak point of compressive arch action, the spatial frame substructure can be superimposed by the planar frame substructure and the cantilever structure. Due to the existence of the out-of-plane transverse beam of the spatial frame, the compressive arch action of the spatial frame substructure is increased by 11.65% compared with that of the planar frame substructure. The vertical bearing capacity of the spatial frame substructure is provided by the beam mechanism of the out-of-plane late transverse beam, but the initial displacements of the catenary action of the spatial frame and the planar frame are not affected. In the stage of catenary action, the out-of-plane transverse beam of the spatial frame substructure can reduce the catenary action by 27.23%, and complete the catenary action by nearly half of the vertical displacement in advance. In the case of progressive collapse of spatial frame substructure, the out-of-plane deflection of the mid-column head may occur, which may reduce the peak value at the arch compression stage by 4.77% compared with the superposition of planar frame substructure and cantilever structure, and reduce the peak value at the catenary stage by 39.04% compared with the superposition of planar frame substructure and cantilever structure. The main difference between the spatial frame substructure and the planar frame substructure comes from the influence of the out-of-plane transverse frame beam, which may cause obvious torsional cracks and serious development and concentration of cracks in the space frame structure, which shall be adverse to the structural forces.
