Static Load Test Study On Progressive Collapse Resistance Of Fully Prefabricated Concrete Frame Structures

In recent years,Chinese government are energetically promoting the precast concrete structures,in which the fully prefabricated concrete structures have the merit of fast installation and less construction pollution.It is worthwhile to study the stability of fully prefabricated concrete frame structures when encounter by accidental loading conditions such as explosion shock,uncontrolled fire and vehicle impact.Based on the experiment of fully prefabricated concrete frame substructures,the paper analyzes the mechanism of progressive collapse resistance of frame structure in the process of removing the middle column.Meanwhile,the finite element analysis models of the test specimens were carried out by the finite element software ABAQUS,and the RC frame model of the whole structure was set up to study the performance of the frame structure to prevent progressive collapse.The main contents are as follows:(1)A space frame structure was designed by PKPM,and three half-scale frame substructure specimens comprising two fully prefabricated specimens(PC1,PC2)and a cast-in-place specimen(RC)were designed according to the frame substructure extracted from the space structure.Each specimen consisted three columns and two beams.The fabricated specimen beam and column were connected by the dowel barcorbel-angle steel.The quasi-static tests were carried out for the three specimens.(2)The test results,including load-displacement curves,beam and column deformation curves at each stage,local strain curves of steel bar and concrete,were arranged,and the ultimate bearing capacity and ultimate displacement of the three specimens were compared.The development and final failure mode of substructure specimens in the removaling of middle column were analyzed.The load transfer mechanism of substructure specimens during the removal of middle columns was discussed.The results provided data support for improving the connection form of the finite element model.(3)Based on the analysis of the test results,the finite element models established by the ABAQUS finite element software were used to simulate the mechanical behavior of the specimens.The simulated curves were in good agreement with the tested curves,as well as the final failure modes of models were similar with the specimens.Based on the simulation,the joint were optimized by changing the parameters of the dowel bar at the beam-column connection of the model,such as increasing the strength or increasing the diameter.It had better mechanical performance on progressive collapse resistance after optimizing.(4)The four RC frame structure ABAQUS finite-element model were established,and the finite element models were verified by the experiment of Qian K.The simulated curves were in good agreement with the tested curves.On this basis,the mechanical behavior of a single layer plane frame structure under different side span constraints and mechanical behavior of a single storey frame structure model considering the action of floor slab and the mechanical behavior of multi-storey frame structure under different floors in the process of removing the middle column were studied.The analysis results showed that the effects of different structural constraints on the collapse stages were different.