The Research Of Mechanical And Seismic Performance For Precast RCS Hybrid Joint

In recent years,with the development of precast buildings,RCS hybrid joints have gradually attracted the attention of researchers at domestic and abroad.While many scientific research achievements have been obtained,the application of practical engineering has gradually increased.However,there are still many shortcomings in the existing research.For example,the current research is mainly on welded RCS hybrid joints,and there are few researches on precast RCS hybrid joints.However,welded RCS hybrid joints have weak seismic performance and are prone to weld brittle fractures.Therefore,in this paper,two kinds of precast RCS hybrid joints based on bolted connection are designed,and the mechanical performance and seismic performance of the j oints and the overall frame are studied by quasi-static test and finite element method.The main research contents are as follows:(1)Carry out quasi-static tests on two types of precast RCS hybrid joints and cast-in-place concrete joints of the same size,compare and analyze the mechanical performance of the three types of j oints according to the collected data,and specifically study the joint failure mode,P-A lag Return curve,ductility,energy dissipation capacity,skeleton curve,etc.The results show that the two precast RCS hybrid joints are semi-rigid joints,and have better stiffness retention capacity,energy dissipation capacity and longer bearing capacity enhancement stage than cast-in-place concrete joints under the same conditions.(2)The displacement angle composition of the two types of precast RCS hybrid joints is analyzed,and the contribution of the joint displacement angle component to the total displacement angle is determined.The results show that the deformation of the two precast RCS hybrid joints is dominated by the bending deformation of the plastic hinge region of the steel beam,.Due to the restraint of the column through bolts,the development of the shear displacement angle of the joint is relatively slow,which prevents the shear deformation of the concrete in the joint area.(3)Use Abaqus finite element calculation software to conduct quasi-static test analysis,and compare with the test results to verify the correctness of the finite element analysis.The results show that the force characteristics and failure mechanism of precast RCS hybrid joints under quasi-static test can be well simulated by using Abaqus software.(4)The finite element method is used to analyze the variable parameters of the two joint forms,and the design method of the precast RCS hybrid joint in this paper is deduced.The results show that the section height of the concrete column and the specification of the connecting bolt have little influence on the bearing capacity of the joint,while the section height of the steel beam,the specification of the column through-bolt and the thickness of the channel flange have a greater influence on the bearing capacity,while the densification of the stirrup in the bending area has a great influence on the bearing capacity.The bearing capacity in the early stage is obviously improved,and the impact in the later stage is small.In the j oint design,the calculation formula of the maximum bending moment and the initial stiffness of the beam end derived by the T-section bending moment calculation method and the component method can better match the test results,while the skeleton derived by the three-line mathematical model and the Takeda model The fitting degree of the curve and hysteresis curve is also high.(5)Carry out structural design based on a building scheme,provide a variety of structural design schemes for the project in the structural design stage,and based on the steel-concrete structure scheme,use SAP2000 software to carry out response spectrum analysis and Pushover analysis for various structural schemes.The results show that the natural vibration period,stiffness,and lateral resistance of the steel-concrete structure are between those of the cast-in-place concrete structure and the steel structure,all the seismic performance indicators are in line with the current specifications,indicating that the steel-concrete structure scheme is adopted,which has good seismic performance.In addition,the addition of infill walls improves the inter-storey drift angle and anti-overturning ability of the steel-concrete structure,which brings better seismic performance to the structure.