Numerical Simulation And Mechanical Performance Of Prefabricated Joint For Partially Encased Composite Frame Structure

In recent years,partially encased composite structure consisting of steel and concrete has received extensive attention in engineering due to its good performance.The combination of prefabrication technology and partially encased steel-concrete composite structure can meet the requirement of industrialization of construction.The effectiveness and reliability of the connection between partially encased beams and column members contribute to the advantage of partially encased composite structure.It is of great theoretical and engineering significance to investigate the mechanical performance of prefabricated joint of partially encased composite frame structures.Numerical simulation under monotonic loading on the partially encased composite joint specimen was conduct by ABAQUS software.The finite element model was established considering the material and contact nonlinearity.The whole process of the composite joint was simulated compared with the test results in terms of the load-displacement curve and the deformation characteristics of the specimen.The results show that the finite element analysis is generally consistent with the test results.Modeling method adopted in this paper can accurately predict the mechanical performance of the partially encased composite joints.Six partially encased composite joints with different parameters considering two types of bolt connections,presence of concrete,height of end-plate,and thickness of column flange were designed.The influence of these parameters on the strength and stiffness of partially encased composite joints were studied through numerical simulation.The load vs.displacement curves and shear force vs.shear deformation relationships of the six specimens were analyzed,as well as the mechanical performance index.Shear mechanism of partially encased composite joints is clarified by analyzing the joint configuration and stress distribution of concrete.The simulation results show that shear strength and stiffness of the partially encased composite joints can be improved by the screw connection instead of the bolt connection.Moreover,filling concrete into the joint region can greatly improve the initial shear stiffness and bearing capacity of the partially encased composite joints.Varying height of end-plate and thickness of column flange have little effect on the strength and stiffness of the partially encased composite joints.concrete diagonal strut mechanism was observed between the upper and lower lateral stiffeners in the joint region.Based on the test and numerical simulation results,shear resistant mechanism and ultimate state of the partially encased composite joint were discussed.A cumulative formula for shear strength of partially encased composite joint was established considering both the steel and concrete.The theoretical calculation results of the shear strength are in good agreement with the test results,and can be used in engineering applications.