ABSTRACT Predicting the long-term deformation and failure of wood under varying environmental conditions is challenging due to the complex rheological behaviour of wood. In this study, the bending failure mechanism and moisture-dependent viscoelastic creep behaviours of Chinese fir (Cunninghamia lanceolata [Lamb.] Hook.) were explored. The digital image correlation technique was used to monitor strain field changes during the bending process. The results revealed that wood in a dry state was more brittle than in a moist state. Strain field variations showed that the tensile load on the tension side primarily governs bending failure. There are distinct differences between tension and compression regions by fracture morphology analysis. The study further developed the time-moisture-stress superposition principle to integrate the effects of time, moisture, and stress on wood's creep behaviour in bending. These findings provide critical insights into how moisture affects wood’s mechanical behaviour, guiding more efficient design and manufacturing practices for long-term structural performance in the timber-construction industry.
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