Cross-laminated timber (CLT) has recently emerged as a new wood product that utilizes a large quantity of domestic lumber. This study aims to analyze the effects of width and lay-ups on the tensile strength of CLT. To this end, the elastic modulus of sugi CLT with different lay-ups was measured by dynamic and static methods. Moreover, tensile tests were conducted for different widths and lay-ups of CLT. Results indicate that the apparent bending Young’s modulus, as calculated using the dynamic method, is directly proportional to the measured Young’s modulus in static method for each lay-up. Furthermore, there was no significant effect of width on the tensile strength in the range of 150, 300, and 600 mm. However, the variations in lay-ups affected the tensile strength as follows: CLT with larger ratio of the major strength direction lamina along the cross-section and with higher grade of lamina in the major strength direction showed higher tensile strength. The estimated tensile strength of CLT, as calculated using the Young’s modulus of the lamina of each layer, and the tensile strength of lamina as simple substance was found to be in good agreement with the measured tensile strength of CLT.
As timber tends to be weak against the load perpendicular to grains, it can be important to study the consequences of applying loads perpendicular to larch cross-laminated (CLT) composed of multiple larch laminae. Compressions tests were conducted perpendicular to the in-plane and out-of-plane grains of Japanese larch CLT. Out-of-pane average compressive strenth, average yield strength, and average compressive stiffness perpendicular to the grain of the larch CLT were 11.94 N.mm2, 7.30 N/mm2, and 7.30 N/mm2, respectively, whereas the in-plane average compressive strength, average yield strength, and average compressive stiffness perpendicular to the grain of the CLT larch were 21.48 N/mm2, 21.18 N/mm2, and 18.72 N/mm2, respectively. The in-plane compressive strength and yield strength showed a statistically significant relationship with the density fo the CLT, the modulus of elasticity measured by longitudinal vibration (MOElv), and the average MOElv of the laminae constructing the cross-laminated timber. The in-plane yield strength was affected by the MOWlv of the outer laminae and the average MOElv of the larch cross-laminated timber. The compressive strength properties were most affected by the loading surface of the CLT. The variation between the moisture content and compressive strength properties of the CLT, however, was not statistically significant.
An investigation was carried out on CLT panels made from Sitka spruce in order to establish the effect of the thickness of CLT panels on the bending stiffness and strength and the rolling shear. Bending and shear tests on 3-layer and 5-layer panels were performed with loading in the out-of-plane and in-plane directions. ‘Global’ stiffness measurements were found to correlate well with theoretical values. Based on the results, there was a general tendency that both the bending strength and rolling shear decreased with panel thickness. Mean values for rolling shear ranged from 1.0 N/mm2 to 2.0 N/mm2.