Rolling shear performance of cross-laminated bamboo-balsa timber panels

This research aimed to develop a set of practical and straightforward test methods to evaluate the rolling shear properties of cross-laminated bamboo and timber (CLBT) panels. Meanwhile, firsthand experimental data on the shear performance of panels laminated with unidirectional engineered bamboo panels and balsa wood lumbers were reported. The mechanical test results for balsa wood used in the hybrid CLBT panels were given. The bonding line's shear test between the out-layer bamboo panels and core wood was performed through the oblique compression shear test. The rolling shear tests of CLBT panels were performed with the two-plate planer shear test method and short-span bending shear test method. The full strain fields of specimens near ultimate loading conditions were given based on the two-dimensional Digital Image Correlation (DIC) method. This study showed that the rolling shear performance of core wood is determined by the annual ring geometrical parameters of wood products in the RT plane. The mean rolling shear moduli were 43 MPa and 48 MPa for two-plate specimens measured with dial gauges and strains, which is estimated through the Digital Image Correlation (DIC) method. The mean shear strength was 0.96 MPa obtained through two-plate shear tests and 2.50 MPa through the short-span bending shear test. The force corresponding to first-crack development instead of the maximum load is suggested to be adopted to calculate the shear strength of CLBT and other hybrid cross-laminated panels. Relatively small modulus and strength values were noticed for the hybrid panels due to the limited contribution of bamboo layers; thus, reinforcement at the stress-concentration regions was suggested for further researches on such lightweight hybrid cross-laminated panels. (C) 2021 Elsevier Ltd. All rights reserved.