Experimental Study On Seismic Behavior Of Through-tenon Joints Under Different Degree Of Looseness In Ancient Wooden Buildings

Ancient Chinese buildings are so imposing and graceful in shape, with distinctive national characteristics. It is a unique architectural system in world ancient architecture history. However, with the passage of time, there are different degrees of damage such as the looseness of mortise-tenon joints, wood decay, bracket set incline in existing ancient wooden buildings. The looseness of mortise-tenon joints is a kind of typical damage type and mortise and tenon joint nodes is important among ancient timberwork system of seismic energy dissipation components. So it is necessary to study the influence of looseness with different degrees on the seismic performance of through-tenon joints, having a good theoretical significance and practical value in engineering. It is important significance to repair reinforcement ancient buildings.The behaviors of through-tenon joints such as the failure characteristics, hysteretic loops and skeleton curve, degradation of rigidity and energy dissipation capacity were studied through low-cycle reversed loading experiment. The results indicate that the failure patterns are mainly partial evulsion of the tenon and the wood fiber at the bottom of the tenon is snapped and extend to the other end. Wood fiber in the variable section torn along the grain and extending to the tenons roots. The shape of hysteretic loops of all joints are Z shaped and the gathering effect gets more obvious with the increase of loose degree. The rotation capacity, stiffness and energy dissipation capacity of the loose joints are significantly below the intact one and reduce gradually as the loose degree increases. Each joint has a good deformation. The ultimate rotation of the loosejoints is above the intact one and increase gradually as the loose degree increases.Finite element analysis of the test on through-tenon joints was simulated by using the software ABAQUS. The deformation maps of mortise-tenon joints, stress distribution maps and skeleton curves were obtained. The nicety of FEM method was verified by comparing the results of FEM method and experiment. On this basis, finite element parameter analysis of the joint is performed. The results indicate that the stiffness, yield bending moment and ultimate bending moment of the joints increase gradually as the height of the mortise, the coefficient of friction, the compressive modulus of elasticity and the tensile modulus of elasticity increases. Tensile strength have little impact on stiffness. Axial force have almost no effect on joint stiffness, yield strength and ultimate bending moment.