Experimental Study On Shear Capacity Of Horizontal Seam In Assembly Integrated Shear Wall

With the development of building industrialization and housing industrialization,the assembly integrated shear wall structure has been developed rapidly.Compared with the traditional cast-in-place shear wall structure,there are many advantages in the assembly integrated shear wall structure,including high production efficiency,quality assurance,convenient construction,low carbon emission,environmental protection and so on.For assembly integrated shear wall structure,the reliability of horizontal seam has a decisive influence on its overall performance.Based on extensive reading of relevant literatures at home and abroad,this paper studies the shear capacity of horizontal seam in assembly integrated shear wall structure.The shear capacity test of four horizontal seam specimens under tension is designed and completed,and the shear capacity of the horizontal seam under monotonic loading is analyzed by finite element simulation as supplements.Then a calculation formula for the shear capacity of interface under tension is proposed,based on ESF(The extended shear-friction theory).The main contents and conclusions are as follows:(1)Four horizontal seam specimens were designed and the design parameters are: area of shear reinforcement of bundle connection,loading modes,stress level of reinforcement.Low-cycle reversed and monotonic loading tests are used to compare and analyze the load-displacement curve,skeleton curve,energy dissipation capacity,ductility and stiffness degradation of the four specimens.(2)The ABAQUS is used to analyze the shear capacity of the horizontal seam in the integrated shear wall under the bundle connection.In the modeling process,plastic damage is introduced into the concrete constitutive model to simulate the damage development and load-displacement of horizontal joints during the test.Compared with the experimental results,ABAQUS can accurately simulate the mechanical behavior of horizontal seam under monotonic loading.(3)The source of the shear capacity of the horizontal seam is analyzed,and the design formula of shearing capacity in different codes are compared.Then the comprehensive ESF theory is selected and summarized,and the improvement and suggestions are proposed.Next,the shear mechanism of the interface under tension is analyzed based on the ESF theory,and a formula for calculating shear capacity of interface under tension is put forward accordingly.Finally,the rationality of the formula is verified by comparing it with the test and design codes.The following conclusions were obtained through research.The ultimate failure state of four horizontal seam specimens in this paper is that the concrete near cluster reinforcement bars is crushed and bulged out,and the seam is completely peeled off from the upper wall and the lower wall.The ductility and energy dissipation of components are poor,and the failure mode of interface is a typical brittle failure.The yield load,secant stiffness and ductility of specimens can be significantly improved by the increase in the area of the bundled shear reinforcement,while the increase of stress level of rebar is on the contrary.The characteristic values of bearing capacity of specimens under low-cycle reversed loading decrease to a certain extent,secant stiffness is smaller,and ductility is significantly reduced.ABAQUS can accurately simulate the mechanical behavior of horizontal seam under monotonic loading.There is a reasonable range in the proposed formula for shear capacity in the interface under tension,which is consistent with the downward trend of the formula in codes.Compared with the shear capacity calculated by the formula,the shear capacity obtained by the test has a certain safety reserve.In conclusion,the proposed formula has a certain application prospect.