Bending and shear performance of cross-laminated timber and glued-laminated timber beams: A comparative investigation

In mass timber construction, cross-laminated timber (CLT) and glued-laminated timber (GLT) usually build a load-bearing system together. Exploring the mechanical properties of CLT and GLT can provide a better understanding and inspiration for designing their members. This study presents a comparative study on the bending and shear characteristics of CLT and GLT beams under the out-of-plane and in-plane loading forms. A series of mechanical properties parameters in the major strength direction were obtained through the tests, and the bending properties were compared with theoretical results. A contribution rate model was developed to quantify the effects of the bending stiffness relationship between adjacent layers in the major strength direction. Under same loading forms, the CLT presented lower bending and shear properties in the major strength direction than the GLT, mainly due to the orthogonal structure inside the CLT. The shear analogy theory showed higher accuracy in the out-of-plane bending results, and the calculation theory that considered all layers could better predict the in-plane bending results. Furthermore, the proposed contribution rate model was consistent with the test results, and it intuitively revealed the effect of the layer stiffness on the overall stiffness for bending specimens under two loading forms.