| The prefabricated concrete frame structure has the advantages of the beam or column components,such as factory prefabrication,high construction efficiency and wide application range.The safety of the connection between prefabricated members at the joints of the prefabricated concrete frame structure is the key to the good seismic performance of the structure.But the current research focuses on the assembly of integral structure,and the existing connection methods still have problems such as quality assurance,high accuracy of construction site operation requirements and higher cost.The common connection methods of fully assembled structure include bolt connection,welding,post tensioned prestressed bar and pin shaft connection.It can not only shorten the construction period,optimize the dry connection node after design,but also repair or replace damaged components after earthquake,which is convenient and quick and saves human and material resources.Among them,pin shaft is a standardized fastener,which can transmit shear force and bending moment in the joint after connecting with ear plate,which is reliable and easy to dismantle.In view of this,a new type of precast concrete beam-to-column connections with precast pin is proposed.For analyzing the seismic performance of the new type of precast concrete joints with precast pin,pseudo static test and numerical simulation analysis on the full-scale sssemble joints is presented.Based on the numerical model,the prefabricated plug assembly type joint was studied parametrically.Finally,the theoretical analysis of the assembled joint was carried out,and the regression analysis was carried out to propose the suitable for the new type of prefabricated plug The seismic recovery model of the assembled concrete beam column joint.The main research work of this paper is as follows(1)In this paper,based on the actual engineering,a four story steel-concrete frame bottom middle node is designed,and a cast-in-place beam column node and two prefabricated plug-inplace beam column joints are designed,and the quasi static test is carried out.The data collected by the experiment are sorted out,and the failure modes and hysteresis curves of the new prefabricated plug assembly joints and cast-in-place joints under the action of low cycle reciprocating load are analyzed.The seismic performance indexes such as bearing capacity,stiffness degradation,deformation capacity,energy dissipation capacity and strain change are analyzed.The results show that the new prefabricated plug-in assembly joint specimen shows ductility failure,but the failure location is different;although the bearing capacity of the new type of assembly joints is worse than cast-in-situ specimen,the stiffness degradation is smaller,the ductility and energy consumption capacity are better than cast-in-situ joints,which shows better seismic performance and meets the requirements of the code.(2)Based on ABAQUS software,a numerical simulation method is proposed to reflect the damage mechanism and mechanical properties of prefabricated plug assembly beam column joints.The skeleton curve,stress cloud diagram and plastic damage of concrete are analyzed and studied.The results show that the model can reflect the key mechanical properties of prefabricated plug assembly joints.Based on the validation of the model,the effects of these parameters on the mechanical properties of the new prefabricated assembly joints are analyzed through thickness of steel plate thickness,the section size of the column and the axial pressure ratio.(3)Based on the test and finite element simulation results,referring to the current domestic and international codes and basic mechanical formulas,the design formula of bending and shear capacity of new type assembly joints is given.On the basis of the test data,regression analysis method is used to propose the seismic recovery model of the new beam column joint,which provides theoretical reference for the seismic performance evaluation of this type of joint. |
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