Experimental Study On Torsional Behavior Of Joint Of Short-limb Shear Wall

Short-limb shear wall combines the advantages of special-shaped columns and shear walls,and its structure is between the two,and it is widely used in the current construction because of its good function.In recent years,many scholars at home and abroad have studied the seismic performance of short-limb shear wall structures.However,most studies focus on the overall horizontal shear resistance and vertical load-bearing performance of short-limb shear walls.The study of the torsional performance of the short-limb shear wall joints is relatively rare.The torsional performance and failure mechanism of the joints of the short-limb shear wall beam wall have not been systematically studied.In order to further study the torsional performance of the joints in the short-limb shear wall structural system,this paper takes a practical high-rise commercial and residential building with an asymmetric plan layout as the research object.The torsional behavior of the short-limb shear wall and connecting beam joints in the middle layer was studied in depth.Taking this as a prototype,the structural model test,FEM analysis and theoretical analysis were carried out respectively.1、A structural test model for connecting joints of short-limb shear wall beams and walls was made with a 1/3 scale ratio.In order to investigate the influence of different limb thickness ratios on joints of wall beams,the limb thickness ratios of structural test models were determined to be 5,6,and 7,respectively.Then,a single horizontal eccentric cyclic load is applied to these structural test models to simulate the combined effects of bending and twisting loads on the joints of short-limb shear walls in actual projects.The results showed that the structural test model exhibits bending torsion failure under horizontal eccentric cyclic loading,and the test model shows a large torsional deformation.The horizontal stirrups provided by the short-limb shear wall play a key role in resisting torsion in the joints,and the vertical reinforcement has a certain auxiliary effect.With the same wall thickness,the increase in limb-thickness ratio can increase the torsional capacity of the joints of short-limb shear wall beams.The joints of the short-limbshear wall are subjected to bending and twisting loads,and the webs will appear oblique cracks at 45° to the longitudinal axis of the wall limbs,and there will be a trend towards the flanges.In the initial stage of applying the load,the core region of the web of the short-limb shear wall mainly plays a role in the torsion process.In the middle and later stages of applying the load,the flanges of the wall limb slowly participate in the torsion of the resistance structure.2、Using ANSYS finite element analysis software,an analysis model for real-size short-limber shear wall jointed beams and wall joints was established.In order to compare the results with the test results,a horizontal and eccentric horizontal concentrated load was applied to the finite element analysis model in accordance with the test model,and the effect of different limb thickness ratios on the joints of the wall-linked beam was compared.By comparing the development of cracks,hysteresis curves,skeleton curves,stiffness degradation curves and T-θ curves near the joints,the failure modes,torsional deformation and torsion bearing capacity of jointed beams and wall joints under bending and torsion were explored.Through analysis,the analysis results of the finite element model agree well with the structural model test results,and the destruction patterns of the two are basically the same.The joints of the T-section short-limb shear wall-connected beam and the wall are subjected to bending and torsion loads.The cracks appear in the web near the joint,and gradually develop to the flanges on both sides of the T-section.In the case of constant wall thickness,increasing the limb-thickness ratio can increase the torsional bearing capacity of the joints,but it has a certain influence on ductility.3、Combined with T-section short-shaft shear wall node model test,finite element calculation analysis and domestic and foreign research results on reinforced concrete torsion members.Further explores the influence of limb thickness ratio on the torsional bearing capacity of short-limb shear wall joints.The calculation formula of the shear force in the core region and the joint torque calculation formula for the T-section short-shaft shear wall jointed beam with wall joints are derived.