Research On Bending Performance Of New Type Shear Wall With Mortise And Tenon Joints

Mortise and tenon connection technology is a kind of horizontal connection technology without overhanging steel bar,through setting mortise and tenon structure on the side of precast wallboard,arranging connection steel bar in horizontal groove,inserting longitudinal steel bar in vertical hole,pouring concrete to realize the connection of horizontal assembly unit,which has the characteristics of good construction quality,high transportation efficiency and fast installation speed.It can effectively solve many problems existing in the current horizontal assembly unit connection.Three Shear wall specimens,including a reinforced concrete shear wall specimen,a precast concrete shear wall specimen with U type closing reinforcement and a new type precast concrete shear wall with mortise and tenon joints(Hereinafter referred to as "new shear wall specimen"),were designed to study the performance of mortise and tenon joints.The failure process and failure state of shear wall with mortise and tenon joints are clarified,the connection performance of mortise and tenon joints is studied,and the influence of joint construction on the bending performance of shear wall is compared and analyzed.(1)Bending failure occurs in all specimens,which is characterized by tensile yield of longitudinal reinforcement in edge members and crushing of concrete at the root.However,the deformation capacity of precast concrete shear wall specimens is greatly increased due to the failure of vertical joints,and the crushing area of concrete at the root is obviously weakened;The failure position of the vertical joint of shear wall with U-shaped closing reinforcement is mainly concentrated at the extended U-shaped closing reinforcement;The failure position of the new type of shear wall is concentrated at the root of the lateral bulge of mortise and tenon structure.(2)The mortise and tenon joint is still in good condition when the new type of shear wall specimen is 1/1000,the wall stiffness is basically equivalent to that of reinforced concrete shear wall specimen,and the mortise and tenon joint is reasonable in constructionand reliable in connection;The flexural bearing capacity of the new shear wall is almost the same as that of reinforced concrete shear wall,and the deformation capacity of the new shear wall is obviously better than that of reinforced concrete shear wall,which indicates that the mortise and tenon joint has no adverse effect on the bending capacity.And the deformation capacity of the wall is improved;Compared with the precast concrete shear wall specimens with U-shaped closing bars,the flexural capacity of the new type of shear wall specimens is significantly improved,and the deformation capacity is basically the same,which indicates that the mortise and tenon joint is better than the vertical joint with U-shaped closing bars.(3)The finite element software ABAQUS is used to establish the numerical analysis model of the new shear wall,and it is clear that the Coulomb friction model is reliable to simulate the interface between new and old concrete.The load-displacement curve is basically coincident with the test curve,and the failure phenomenon of the numerical analysis model is in good agreement with the test results,which indicates that the numerical model established is reasonable and reliable.(4)Based on the numerical analysis model,the key parameters such as the axial compression ratio,the amount of edge longitudinal reinforcement and the strength grade of concrete are compared and analyzed.The results show that the influence law of these parameters on the mechanical behavior of the new shear wall conforms to the general law of reinforced concrete shear wall.