Research progress on rotational hysteretic mechanical models of mortise-and-tenon joints in traditional timber structures

Mortise-and-tenon joints in traditional timber structures are typical semi-rigid connections, and their rotational hysteresis models provide a theoretical basis for accurately evaluating seismic performance. This paper is a systematic review on the load-transfer mechanisms and hysteretic behaviour of representative joint types, including straight-tenon, through-tenon, and dovetail joints. Based on common features of existing hysteresis models, this review organizes backbone curves, pinching rules and degradation modifications into a three-component framework for classifying and comparing different models. The applicability of empirical restoring-force models, mechanics-based analytical models, and finite element numerical models is comparatively assessed. In addition, the mechanisms by which joint geometry, fit accuracy, timber properties, and service environment affect model parameters are discussed. Although existing models can capture the fundamental hysteretic response of intact joints, limitations remain in representing post-peak softening, parameterizing pinching effects, modelling multi-factor coupled degradation, and ensuring applicability across different joint types. Future work should establish a quantitative parameter framework for the pinching effect across different tenon configurations, develop parameter correction methods for hysteresis models under coupled multi-damage conditions, improve parameter transfer among modelling approaches, and validate damaged mortise-and-tenon joint models against field measurements from historic timber buildings. These efforts will support seismic assessment and strengthening design for traditional timber structures.