Punching shear resistance of point-supported CLT panels

Cross-laminated timber (CLT) panels can provide two-way span resistance in point-supported floor applications where the panels are directly supported by columns, providing increased free story height and a flexible room layout. Previous research has shown that in the vicinity of point supports, CLT punching shear resistance under bi-axial loading is enhanced when compared to the CLT rolling shear resistance under uniaxial shear stress. In addition, due to the two-way bending of the panels and the resulting deformed shape, the effect of support condition on the resistance should be considered when designing point-supported CLT floors. In this research, 164 full-scale CLT panels were tested under punching shear to study the impact of column location, point-support area, out-of-plane stiffness of the load distribution plate, and timber species on CLT punching shear resistance. Punching shear resistance was primarily influenced by column location and point support area; and using a load distribution plate with a smaller out-of-plane stiffness helped to reduce stress concentrations. An analytical model is proposed for point-supported CLT floor design in punching shear, which accounts for the increased rolling shear strength and the shear stress concentrations for different column conditions. • The rolling shear strength of CLT exhibits enhanced performance under localized shear stresses and punching shear loading. • Material-strength and column-condition related adjustment factors are required to calculate CLT punching shear resistance. • The transformed-section method precisely estimates CLT shear-stress distribution while accounting its orthotropic nature .