An investigation of the DOL effect of wood in tension perpendicular to grain

In this study, both short-term and long-term tests in tension perpendicular to grain on Northeast China Larch small clear specimens taken from glulam were conducted, in which the specimens for short-term test and the specimens for long-term test were treated as matched samples that followed the same strength distribution. The DOL effect was determined as the ratio of the applied stress of a failed specimen from the long-term test to the strength of the matching specimen of the same percentile from the short-term test. It was found that the DOL effect was more severe than that predicted by the Madison Curve for the duration shorter than one hour or so and less severe for the duration between one hour and one year by the end of the long-term test. Also, the test result showed that the MOE perpendicular to grain decreased slightly after long-term loading, but the decrease was less severe than the loss of the strength. The deformation factor of creep perpendicular to grain was found to be 2.17, which is close to the deformation factor of OSB in Service Class 1 as specified in Eurocode 5. Furthermore, the Foschi and Yao DOL model and the Nielsen DOL model were calibrated with the test data and the long-term strength can thus be predicted by the calibrated DOL models.