Comparison of Test Methodologies for Computing Bending and Shear Stiffness of Cross-Laminated Timber

Abstract

Abstract Current testing methods for evaluating the out-of-plane bending and shear stiffness terms of cross-laminated timber (CLT) materials use a relatively long span panel. When new CLT layups and composites are proposed, especially when manufactured from pilot-scale facilities, the length requirement may be a barrier for material property evaluation. The purpose of this paper was to compare current bending and shear stiffness test methods of CLT with alternative forms, including a simultaneous calculation method and the five-point bending test, which uses a shorter beam than current testing methods. Both experimental evaluation and finite element modeling of the mechanical properties were used to compare the proposed test methods. In general, numerical and experimental results demonstrated that effective bending stiffness (EIeff) values of CLT panels evaluated by different test methods were similar (maximum 12.7 % difference). Effective bending and shear stiffness values from the finite element method (FEM) agreed with experimental results. FEM demonstrated that both the simultaneous solution and the five-point bending test can be used as alternative test methods for evaluation of the bending and shear stiffness for CLTs. However, the effective shear stiffness values of CLTs from current industry standards were at least 450 % less than both the experimental evaluation and FEM prediction.