Long-term creep behavior of glulam member under compression and bending moment

In this study, 12 glulam members were designed and tested, considering the effects of stress ratio and relative eccentricity. After the 180-day test period, the results showed that increasing the stress ratio and relative eccentricity led to large initial elastic deformation and creep deformation, and the creep coefficients at 180 days for the glulam members under higher stress ratio and relative eccentricity were lower than those for the glulam members under lower stress ratio and relative eccentricity. Typical empirical and mechanical models and a modified model were chosen to fit the creep coefficient curves. The fitting analysis indicated that the values of the R² for all creep models were larger than 0.90, reflecting the goodness of fit. Employing the modified model, the prediction of the creep coefficient for the compressive-bending glulam member over 50 years was conducted. The results found that the glulam members under high relative eccentricity and stress ratio exhibited low creep coefficients, of which values approached to 0.7. Compared to creep coefficients specified in current standards and literature, the creep coefficient of 1.5 at a 50-year period for the compressive-bending glulam members was recommended, aiming to provide a reference to the long-term design of the compressive-bending glulam member in practice.