Experimental Study on Seismic Performance of Artificially Simulated Damaged Hoop Head Mortise–Tenon Joints

Hoop head mortise–tenon joint is a traditional wood connection technique used in ancient Chinese timber structures, characterized by the interlocking of mortise and tenon and the anti-extraction effect of the hoop head. In order to study the mechanical properties of damaged hoop head mortise–tenon joints, this paper explores variations in parameters, including the size, depth, location and shape of damaged areas, column axial force, and timber types. Seventeen scaled specimens, including both intact and artificially damaged joints, were analyzed through low-cyclic repeated loading tests. The results demonstrate that in the case of specimens crafted from Merbau and Tectona grandis, the primary damage modes entail longitudinal tensile cracking of the beam tenon on the inner side of the column and vertical splitting of the beam tenon on the outside of the column. In contrast, specimens made of Chinese fir (Cunninghamia lanceolata) were free of noticeable cracks but exhibited manifest compressive deformation at the edges of the beam-column junctions. An increase in the axial force of the column leads to higher peak bending moments and enhanced energy dissipation capacity while reducing ductility. Irrespective of timber type, heightened total damage degree substantially diminishes the peak bending moment, ductility, and energy dissipation capacity of the joints. The location and shape of the damaged area exert a specific influence on the peak bending moment, ductility, and energy dissipation capacity of the joints. Nonetheless, the underlying patterns are not readily discernible and exhibit a degree of randomness.