Experiment and theoretical study on mortise-tenon joints reinforced by support-type viscoelastic damper

This paper proposes the utilization of support-type viscoelastic dampers to enhance the seismic performance of traditional timber mortise-tenon joints. Four viscoelastic dampers and three T-shaped mortise-tenon joints were manufactured, with two dampers designated for performance testing and the remaining two dampers installed on the mortise-tenon joints. Subsequently, cyclic loading tests were carried out on the reinforced mortise-tenon joints and two control mortise-tenon joints. A comparative analysis was conducted on the changes in the moment-rotation hysteresis curve, skeleton curve, stiffness, and energy dissipation capacity before and after joint reinforcement. Based on the observed deformation characteristics of the joints during the tests, a theoretical moment-rotation model for the reinforced mortise-tenon joint was derived and juxtaposed with the experimental results. The study demonstrates that the viscoelastic dampers exhibit stable stiffness and exceptional energy dissipation under cyclic loading. In contrast, the stiffness of the mortise-tenon joints from the control group degrades significantly with increasing rotational deformation, whereas the joints with dampers maintain relatively stable stiffness. The installation of dampers led to a remarkable improvement, with the maximum moment-bearing capacity and average stiffness increasing by 2.3 times and 1.5 times, respectively. The total energy dissipation of the reinforced joints under the same loading reached 2.69 kN·m·rad, representing a 1.8-fold increase compared to the control joints. The calculated results of the theoretical moment-rotation model for the reinforced joints align well with the experimental results, providing a robust theoretical foundation for the application of support-type viscoelastic dampers in strengthening mortise-tenon joints.