Mechanical properties of EDMC specially used for strengthening mortise–tenon joints of timber structures

The energy-dissipation metal connector (EDMC) is a novel seismic strengthening device for traditional oriental timber structures. By utilizing the shear deformation of high-damping rubber, the EDMC enhances the stiffness and damping capacity of mortise–tenon joints, enabling effective energy dissipation and vibration control. To investigate its mechanical behavior-including rotational deformation, loading-frequency response, and low-cycle fatigue-six specimens with two rubber formulations were tested under quasi-static loading. The results show that the EDMC maintained stable performance, exhibiting only minor defects such as microcracks in the rubber layer, surface irregularities, and slight loosening of outer bolts at large displacement amplitudes. Moreover, the restoring force characteristics remained relatively stable under different testing conditions. As the displacement amplitude increased, both the load-bearing capacity and energy dissipation capacity increased, while the stiffness and equivalent viscous damping coefficient decreased. Under higher loading frequencies and increased numbers of cycles, all mechanical indicators initially decreased significantly before stabilizing. Furthermore, the shear characteristics and plastic behavior of the damping rubber determined the load-bearing capacity, stiffness, and energy dissipation capacity of the device, respectively.