Seismic behavior of mortise-tenon joints reinforced with lightweight steel components

Mortise-tenon joints (MTJs) exhibit good energy dissipation and have been widely used in wooden houses since ancient times. Based on the failure mode of wood joints, reinforcement methods for MTJs, such as steel strip plate (SSP), hollow rectangular steel plate (HRSP), diagonal bracing steel plate (DBSP), grooved steel plate with triangular stiffener (GSPTS), and angle steel with double triangular stiffener (ASDTS) reinforcement, have been proposed. Low-cyclic loading tests were conducted on 11 wood joints to investigate their seismic performances. The failure characteristics, hysteretic curve, skeleton curve, stiffness degradation, energy dissipation, tenonpulling value, and strain were compared and analyzed. The experimental results indicated that the failure modes of joints with or without reinforcements were beam pull-out, self-tapping screw pull-out, and shear failure. The joint with ASDTS reinforcement exhibited the best seismic performance, followed by HRSP, DBSP, and SSP reinforcement. The seismic performance of joints with GSPTS reinforcement was better in the early loading stage but became poor in the later stage owing to the deformation of the GSPTS reinforcement, causing damage to the timber. A detailed numerical simulation was performed, and the results indicated that with the improvement in the moduli of elasticity parallel and perpendicular to the grain, and friction coefficient, the stiffness and peak bearing capacity of the wood joints increased. Increasing the yield strength of the selftapping screw and steel plate had a slight effect on the initial stiffness, but it increased the peak bearing capacity of the wood joints.