Investigation of the effect of growth ring orientation on the shear properties of sawn timber

Abstract This study investigates the influence of growth ring orientation on the shear behavior of engineered timber, with the objective of improving the structural performance and optimizing the design of cross-laminated timber. Four groups of spruce-pine-fir samples with different growth ring orientations were selected for analysis: 6° (Group H), 37° (Group I), 85° (Group J), and with the pith at the center of the sample (Group K). V-notch shear tests (Iosipescu shear tests) were carried out by ASTM D5379/D5379M-19. The test results showed significant differences in shear performance among specimens with different growth ring orientations. In particular, Group I and Group K exhibited the higher shear performance, with average shear strengths of 3.89 MPa and 4.25 MPa, and shear moduli of 376.92 MPa and 270.38 MPa, respectively. In contrast, Group J showed the lowest shear performance, with an average shear strength of 2.13 MPa and a shear modulus of 56.85 MPa. The shear properties of Group H were intermediate between those of Group I and Group J, with an average shear strength of 3.00 MPa and a shear modulus of 149.53 MPa. Analysis of the load–displacement curves and stress–strain curves indicated that Group I and Group K had higher yield strength and stiffness before failure, while Group J exhibited better ductility.