Experimental Analysis on Seismic Performance and Damage Assessment of Loose Through-Tenon Joints

This study experimentally investigates the seismic performance degradation and damage mechanisms of full-scale through-tenon joints with varying degrees of looseness. A comprehensive methodology combining quasi-static cyclic tests and acoustic emission (AE) monitoring was employed to quantify the effects of looseness on failure modes, hysteretic behavior, energy dissipation, and damage evolution. Results demonstrate that increased looseness significantly reduces the joint’s load-bearing capacity, stiffness, and energy dissipation ability. Loose joints exhibit asymmetric damage under positive and negative loading, with cracks initiating at stress-concentrated regions (e.g., tenon root or notch section) and progressing along perpendicular-to-grain directions. AE analysis, including b-value trends and RA-AF correlations, reveals a shift from mixed tensile-shear damage to shear-dominated failure as looseness increases. Clustering of AE parameters further distinguishes three damage modes: matrix failure, interface debonding, and fiber fracture, with the latter showing a 71% reduction in energy per hit in severely loose joints. The deterioration of seismic performance is attributed to amplified slippage deformation and reduced effective contacting areas within the joint. These findings provide a theoretical basis for seismic analysis and damage assessment of through-tenon joints in traditional timber structures.