Seismic Performance Experiment and Deformation Damage Assessment of Full-Scale Loose Dovetail-Tenon Joints

This study investigates the seismic damage mechanism and deformation damage characteristics of loose dovetail-tenon joints through pseudo-static loading, and forms a complete “AE monitoring-damage quantification-safety early warning” research chain. Three groups of full-scale larch joints with 0%, 15% and 30% tenon length reductions were tested with real-time acoustic emission (AE) monitoring. A damage assessment model was then established, and an early-warning method was proposed. Results show that increasing looseness aggravates strength and stiffness degradation, reduces energy dissipation capacity but enhances deformability, with failure dominated by tenon pullout and tenon-mortise compressive deformation at the tenon-mortise interface. The cumulative AE energy and ring counts rise sharply with damage progression, coupled with a continuous b-value decline, indicating the transition to shear-dominated macroscopic failure. Through systematic AE parametric analysis covering b-value and RA-AF correlation, the progressive and cumulative damage evolution from micro-scale initiation to final failure is characterized. A damage assessment model is established to quantify joint damage status, yielding only minor deviations from the classical Park–Ang model. Furthermore, a targeted early-warning method is developed with the AE rate parameter A0 as the critical threshold, enabling full-process damage evaluation and stage identification, and providing a reliable theoretical basis for practical structural safety monitoring.