Research On Seismic Behavior Of The Joints Consisting Of Confined Concrete Wall-format Column With Spiral Stirrups And Steel Beam

The confined concrete wall-format column with rectangular spiral stirrups(wallformat column for short)proposed by our project group is between 2～4,and its width is same as the building wall.The wall-format column has good ductility and energy dissipation capacity,and it can be used as a vertical load-bearing and lateral force resisting members in the reinforced concrete column-steel beam(RCS for short)composite structure.Due to the large ratio of wall-format column section length to width,the traditional RCS composite joints such as inner partitions,outer ring plates and bolted endplates are not applicable in the strong axis direction of wall-format column;The lateral stiffness of wall-format column is low and the steel beam often needs eccentric disposal for the requirements of building elevation and function.The wall-format column would be buckling by these factors under the bending moment at beam end.In view of these situation,one group of new through-column-type prefabricated joints consisting of confined wall-format concrete column with spiral stirrups and steel beam are proposed which includes in-plane side-plate joint and out-plane through steel bar-end plate joint(out-plane through steel bar joint for short).The beam and column of this new RCS composite structure can be hidden in the wall and has flexible layout,which can provide large space for building.This structure can meet the owner demands on residential type and can be used in prefabricated residence.The numerical simulation is used to analyze the mechanical behavior and seismic performance of this type joints in this paper,the main research work are as follows:(1)The mechanics performance of high-strength concrete columns confined by highstrength lateral ties and RCS composite joint was simulated.The analytical results agree well with the test data and failure modes.From the conclusion,we can find the material constitutive model which are applicable to the in-plane side-plate joints and out-plane through bar-end plate joints.(2)The process of bearing capacity of in-plane side-plate joints and out-plane through steel bar-end plate joints were simulated under low cyclic lateral loading。The seismic performance of joints in terms of failure modes,hysteresis and skeleton curve,ductility,energy dissipation capacity and stiffness are studied.The results indicate that:The beam ends form plastic hinge,showing good ductility and energy dissipation capacity.The in-plane side-plate joints and out-plane through steel bar-end plate joints show obvious characteristics of strong joints and weak pole.(3)The impact factors of the axial-pressure ratios,side-plate extension length,sideplate thickness,underside-plate extension height on seismic performance of in-plane sideplate joints were studied,research suggests that: The joints have good ductility and energy dissipation capacity at higher axial compression ratio;Increasing the elongation of the side-panel can improve the initial stiffness,bearing capacity and ductility;The side-plate thickness can affect the failure mode of the specimen;Increasing the elongation of the underside panel can reduce the damage degree of core concrete.Combining abovementioned parameter analysis,the design suggestion and construction measure of inplane side-plate joints are proposed.(4)The impact factors of the eccentricity,the thickness of joint separator plate and joint web plate on seismic performance of out-plane through steel bar joints were studied,research suggests that: When the eccentric distance of beam-column is too length,the column and beam of joints were bend and torsion under end-column partiality loading;The thickness of joint separator plate can effectively affect the ductility,bearing capacity and failure mode,but the thickness of joint web plate has little influence on seismic performance;The through steel bar and welding seam shares the stress of the end beam,the welding seam takes on maximum stress.Combining above-mentioned parameter analysis,the shear capacity of out-plane through steel bar joints were proposed by the load transferring mechanism of joint.