Study On Seismic Behavior Of Assembled Joints Between Precast CFST Laminated Columns And Precast RC Beams

As a new type of steel-concrete composite structure,the CFST composite column has high bearing capacity and excellent seismic performance,and has good application prospects in practical engineering.So far,there have been some studies on CFST composite columns at home and abroad,but there are few studies on the connection joints of CFST composite columns,and fewer studies on prefabricated CFST composite columns and prefabricated RC beam assembly joints.High-strength blind bolts have the advantages of quick construction,saving manpower and time costs,and ensuring the quality of the structure.They can solve the difficult problem of installation in closed cross-section structures,so they are widely used in projects requiring high quality and fast construction.Under the concept of industrialization of prefabricated buildings proposed by the state,the combined application of prefabricated CFST composite columns and high-strength blind bolts is of great value for the promotion of the assembly of building structures.Therefore,in this paper,the prefabricated concrete-filled column and prefabricated RC beam joints are studied,and the seismic tests of 1 cast-in-place joint as control group and 2 prefabricated assembly joints under low-cycle repeated loads are designed and conducted.Combined with finite element numerical analysis,the mechanics of joints are further studied Performance and failure mechanism,as well as the effects of different loads,geometries,and material parameters on the fabricated joints of precast CFST composite columns and precast RC beams.This article mainly performs the following work:(1)2 prefabricated assembly joints and 1 cast-in-place joint seismic tests were designed and carried out The failure modes of joints,load-displacement hysteresis relationship,bending moment-rotation hysteresis relationship,joint ductility,energy dissipation capacity,stiffness degradation and strength degradation,strain distribution of key parts,etc.were studied,as well as mechanical performance and failure mechanism of prefabricated RC beam assembly joints.(2)The finite element software is used to perform numerical analysis on the three prefabricated CFST composite columns and RC beam joints,considering the material constitutive relationship,complex contact between materials,element types,meshing,boundary conditions,contact methods,etc.Under the premise of factors,a reliable and accurate node numerical model is established,and the joint is analyzed in a non-linear whole process.The mechanical performance and failure mode of the prefabricated CFST composite column and prefabricated RC beam assembled joint are further studied.(3)The finite element software is used to analyze the parameters of the three kinds of joints.The main parameters are set to steel strength,concrete strength,bolt preload,bolt diameter,longitudinal reinforcement diameter,axial compression ratio,steel content of superposed column section,connection Slab thickness,etc.,to explore its effect on the load-displacement relationship,bearing capacity and initial stiffness of the joint,further study the static performance of the prefabricated CFST composite column and prefabricated RC beam joint under different parameters affected by different parameters,to provide a reference for the application of such joints in actual engineering.According to the above work results,it is shown that the prefabricated CFST composite column and the prefabricated RC beam assembly joint have high bearing capacity and good seismic performance,and have broad prospects in practical applications.The research results of this paper have reference value for the further theoretical research and engineering application of such joints.