Experimental Study On Seismic Performance Of New Prefabricated Steel-reinforced Concrete Beam-column Joints

In recent years,in order to realize the transformation of the construction industry,the construction industrialization with prefabricated buildings as the core has been strongly supported by national policies.Compared with the traditional cast-in-place reinforced concrete structure,prefabricated building has the advantages of high construction efficiency,low energy consumption and low environmental pollution.However,the existing prefabricated joint connection structure is complex,the joint seismic performance is poor,and the column angle and the joint core area are prone to brittle shear failure.At present,the research focus of the development of the prefabricated building is to optimize the connection structure and improve the seismic performance of the prefabricated connection.The combination of steel and reinforced concrete is one of the ways to solve the above problems.However,the existing connection area of this connection mode is concentrated in the beam end,the joint structure is still complex,and the bearing capacity of the beam end is difficult to guarantee.At the same time,the bearing capacity of the beam end is large,which leads to the plastic hinge at the beam end,the shear failure of the joint and the reduction of the structural integrity and seismic performance.In order to solve the shortcomings of the existing steel-concrete structure joints,this paper proposes a new prefabricated steel reinforced concrete connection mode,which makes the connection area of the prefabricated joint move from the outside of the beam end to a certain distance from the beam end,and makes the assembly connection from the column to the beam into the beam to the beam connection form.The connection structure is simple to ensure the connection of the fabricated structure The connection mode is reliable and the overall structure has good seismic performance.In this paper,a new type of prefabricated steel reinforced concrete frame joint is proposed.The prefabricated concrete beam and the prefabricated concrete column are connected by bolt and welding with embedded I-beam,and the plastic hinge is moved from the outside of the core area of the joint to the beam by changing the section of the joint area.The seismicperformance and plastic hinge of the prefabricated steel reinforced concrete frame joint are studied The following research work has been carried out on the assumption of outward migration:(1)Four full-scale specimens were designed and fabricated,including three joints in prefabricated steel reinforced concrete frame and one joint in traditional reinforced concrete frame.The specimens were tested by pseudo-static test of low cycle reciprocating horizontal load,the development of specimen change during loading was recorded,and the data of specimen displacement,rotation and strain were collected;(2)Based on the recorded situation and the collected data,the failure rule of the specimen is summarized,and the failure mechanism of the specimen is analyzed qualitatively with the development of the apparent concrete crack and the strain of the reinforcement;(3)Through the comparison of different parameters(axial compression ratio,post cast concrete type and structure type),the load displacement hysteretic curve and skeleton curve are analyzed,and the seismic performance such as strength degradation,stiffness degradation,ductility and energy dissipation capacity are studied.The influence of each parameter on seismic performance is summarized.(4)Processing the data of strain and rotation displacement,drawing the deflection curve and strain curve of the beam,combined with the development of the crack in the core area of the joint,verifying the feasibility of the plastic hinge outward moving.