Seismic Behavior of Predamaged Mortise-and-Tenon Joints Reinforced Using Viscoelastic Dampers

Abstract

Mortise-tenon joints are the key load-bearing and energy-dissipating connections in conventional timber structures. The stiffness and damping ratio completely degradation of the key joints in an existing wooden frame due to resistance to several seismic events. Accordingly, an efficient and appropriate repair and reinforcement method for damaged mortise and tenon connections is needed. This paper follows a direct displacement-based design procedure to quantify the mechanical performance parameters of viscoelastic dampers, thus supplementing the two degradation characteristics of earthquake-damaged joints in a conventional timber structure. The reinforced joints are designed for performance objectives that restore the seismic abilities and limit the tenon pull-out. Meanwhile, the maximum rotation angle of the reinforced joints satisfies the Chinese code-based rotation angle limit value of 0.033 rad requirement. For this purpose, quasistatic cyclic predamaged tests were first conducted on twelve mortise-tenon joints with four connection configurations. Subsequently, the predamaged joints were reinforced with a designed viscoelastic damper and reloaded. Test results indicated that the original cracks did not propagate in the design rotation angle limit of 0.1 rad after adding a damper. Moreover, smaller lengths of tenon pull-out, lower strength degradations, excellent bearing capacities, and sufficient energy dissipation capacities were demonstrated by the reinforced joints.