Experimental Study On Mortise Joints Modeling Of Chinese Traditional Timber Structure

Chinese ancient timber buildings are excellent historical and cultural heritage. Mortise and tenon connection is different from other structure formation. Mortise-tenon joint is semi-rigid connection, and it makes the timber structure has good seismic energy dissipation effect. The study of the constitutive relation of timber structure joints is of great importance for wood structure seismic theory. The constitutive relation of timber structure joints is closely related to the friction mechanism and embedment mechanism of wood. Therefor, the study on the influence of friction on seismic behavior of tenon joints has important theoretical significance.Through-tenon joint, half-tenon joint, silver ingot mortise-tenon joint and dovetail joint are selected in this study. The friction is changed by changing the lateral face closeness of the mortise-tenon joint. The specimens were made of Chinese fir and pine. The seismic behavior of these joints were tested by quasi-static test. The seismic performance, including failure mode, hysteretic loops, skeleton curve, stiffness degradation, joint deformation capacity, energy dissipation capacity, pull tenon amount and strain of four types of joints with different closeness configuration were extracted from test results.The test results indicate that the main failure mode of through-tenon joint is compression perpendicular to grain of wood and crack of tenon. Tenon extract is the main failure mode of half-tenon joint. The failure mode of the silver ingot mortise-tenon joint is mainly compression perpendicular to grain of wood in tenon neck region. The failure mode of dovetail joint is mainly tenon extract and mortise splitting. Beams and columns of all test pieces are not deformed obviously.The hysteresis curves of each joint showed a, reverse Z shape with a significant pinch effect. The joint bearing force, energy dissipation capacity and rotational stiffness arranged from big to small are through-tenon joint, silver ingot mortise-tenon joint, dovetail joint and half-tenon joint. Mortise-tenon joints have good deformation ability for the ultimate angle of mortise-tenon joints is basically greater than 0.11 rad, except through-tenon joint. Silver ingot Mortise-tenon joint has a small amount of tenon extract because of its special shape. With the increase of the tightness between mortise and tenon, the bearing force, energy dissipation capacity, rotation stiffness and the amount of tenon extract increase, but the deformation ability decrease simultaneously. The rotation stiffness, bearing capacity and energy dissipation capacity of pine specimen is also greater than that of Chinese fir.