This article aims to disclose that the deformation and damages of the one-way straight mortise-tenon (OWSMT) joint, the key force transmission connection of traditional wood buildings, lead to a significant reduction in structural safety of ancient timber structure. For this purpose, the damage of mortise joint in practical engineering wassimulated by controlling the gap and width between mortise and tenon. A total of 23 groups of scaled 1:2 OWSMT joint specimens were fabricated and tested subjected to cyclic loadings, and the hysteretic curves of OWSMT joint with different damage degrees were obtained. Through skeleton curves, stiffness degradation curves, and equivalent viscous damping curves of the OWSMT joint, the seismic performance of damaged wood joints was quantitatively analyzed. The results show that, with the increase in the gap between the tenon and the mortise, the slip between them became increasingly obvious, the fullness and peak of the hysteresis curve gradually decreased, the gradient of the skeleton curve also dropped, and both the stiffness degradation curve and the equivalent viscous damping curve are gradually reduced. The research findings shed new light on the seismic assessment of aging timber buildings.

Being exposed to weather directly or indirectly for more than 100 years, ancient timber buildings have experienced different levels of mechanical degradation. Especially the mortise-tenon joints, which play a crucial role in resisting various loads for these buildings, have suffered from severe deformations and damages, resulting in a significant reduction in the structural safety for the ancient timber buildings. In this study, a method is proposed to quantitatively describe the destruction of one-way straight mortise–tenon (OWSMT) joints, and the impact of joint damage on the seismic performance of the ancient timber structure was studied. The deterioration of the mortise-tenon joints was simulated by changing the size of the mortise, and controlling the width of the mortise compression zone and the gap between the tenon and the mortise. Low-cyclic loading tests were carried out on 23 groups of OWSMT joint specimens. The structural performance in terms of $M\text{-}\theta$ skeleton curves, stiffness degradation, and equivalent viscous damping of the OWSMT joints were obtained. Through the comparative analysis of the experimental and numerical simulation results, this paper further analyzes the seismic performance of the damaged timber joints.

Mortise–tenon joints (MTJs) have been playing a crucial role in traditional timber structures to resist service and earthquake loading. In the present work, an experimental study was carried out to investigate the seismic performance of joints of ancient timber structure. Five types of joints from Fu-Jiu Zhou house, a historical building in Yangzhou city, were selected as the test prototype. All of the members of the test specimens were directly extracted from the aged building and were manufactured according to traditional methods. Based on the cyclic loading tests, efforts have been made to investigate the hysteresis curves, backbone curves and energy dissipation of the MTJs. The test results indicate that the bearing bracket in the tenon can improve pulling-out resistance capacity, rotational stiffness and energy dissipation of MTJs, and reduce the bending capacity. It is suggested that the dovetail MTJ may be one of the best connection configurations for pulling-out resistance and bending capacity.

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