Physical and mechanical behaviors of thermally modified rubberwood glulam beam under sustained cyclic loading

Abstract

This study evaluated the effect of thermal modification on the physical and mechanical properties of rubberwood glued laminated (glulam) timber. The flexural creep property and cyclic loading behavior were also investigated. The obtained results indicated that the MC and specific gravity of thermally modified rubberwood decreased with an increase in modification temperature. Moreover, the flexural strength of the rubberwood glulam timber at modification temperatures of 180 and 220°C was 8.57% and 46.72%, respectively , which was less than that of the control rubberwood dried at 90°C. However, the MOE between the thermally modified rubberwood glulam timber and control specimens was not significantly changed. The flexural creep test indicated that the maximum relative creep of the thermally modified rubberwood timber equaled 0.31, which was lower than that of other natural timber and tended to decrease when increasing the stress level. Various mathematical models were also proposed, and the best-fitted model was found to be the Bailey-Norton power law model. Nevertheless, the cyclic loading results also proved that thermal modification temperature had a direct effect on the ductility index and energy dissipation of rubberwood glulam timber, but it had no significant effect on the impairment of strength.