Experimental and Numerical Investigation on Seismic Performance of One-Way Straight Mortise–Tenon Joints Based on a Novel Method to Simulate Damage of Deteriorated Ancient Chinese 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-θ 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.