Effect of Thickness and Lamina Species Combination on Bending and Shear Properties of Cross Laminated Timber (CLT) Panel

Cross-laminated timber (CLT) is an innovative engineered timber material used in the research and development phase in Indonesia. Therefore, the characteristics of CLT based on local timber species must be investigated in depth. The purpose of this study was to investigate the effects of the thickness and lamina species combination of local timber on the bending stiffness and shear stress of CLT. CLT with two different thicknesses of 51 mm (17/17/17 mm) and 67 mm (25/17/25 mm) and two different lamina configurations of acacia CLT and a combination of two species Acacia mangium (acacia) and Melia azedarach (mindi) became a hybrid CLT. An increase in the acacia CLT thickness had a positive effect on the bending stiffness. The bending stiffness of acacia CLT with a thickness of 67 mm was 3.77 times higher than that of acacia CLT with a thickness of 51 mm, whereas in hybrid CLT, it increased by 3.38 times. In terms of shear stress, the effect of thickness was not significant on Acacia CLT, as it showed a decrease of 0.01 MPa, whereas hybrid CLT experienced a reduction of 0.29 MPa, which is approximately 19.71%. The bending stiffness test results on CLT with uniform lamina thickness can be predicted using popular theoretical approaches, such as Shear analogy, Gamma theory, and Timoshenko theory. Meanwhile, the prediction of the shear stress using the Shear analogy was the closest to the test results for the entire CLT configuration.