Experimental Investigation On The Rheological Behavior Of Timber In Longitudinal And Transverse Compression

Understanding the rheological behavior of timber is vital for evaluating the long-term performance of timber structures. In this study, short-term experiments were first conducted to obtain the short-term mechanical properties of timber including yield strength and elastic modulus in both longitudinal and transverse compression. Subsequently, creep tests were carried out to capture the rheological behavior of timber over 360 days. Different loading types of compression and stress levels were chosen in the creep tests. Environmental temperature and relative humidity, moisture content, environmental strain and creep strain were monitored. The coefficients of environmental deformation and irrecoverable mechano-sorptive creep were obtained in longitudinal and transverse directions. Various creep models of timber were calibrated against the experimental data. Weighted nonlinear regression was adopted to better simulate the secondary creep behavior. The creep coefficients over 50 years were estimated using the calibrated models, which were compared with values from existing national standards and research. The experimental results demonstrate that the limit of linear creep in longitudinal compression was bigger than that in transverse compression. Also, the transverse timber creep was much bigger than the longitudinal creep.