Shear properties of hybrid CLT fabricated with lumber and OSB

Recently, to enlarge the source of raw materials and improve the mechanical properties of cross-laminated timber (CLT), some local wood species, hardwood and Engineering wood products were used to fabricate CLT. This project studied mainly the feasibility of using construction oriented strand board (COSB) to fabricate hybrid CLT (HCLT). The shear properties of the HCLT were reported in this paper. The mechanical properties of COSB in major and minor strength directions were firstly obtained by various span bending tests and compression tests. The shear resistance and stress in major and minor strength direction of five groups of 3- and 5-layer HCLT, having different lay-up arrangements, were evaluated by experiments, shear analogy theory as well as FE methods. Results showed COSB had higher mechanical properties in minor strength direction compared with SPF dimension lumber. Different HCLT groups had different failure modes observed for major and minor direction. Except to the rolling shear failure of SPF transverse layer and tension failure of gaps between the lumber of the bottom layer, the longitudinal and transverse shear delamination failures and tension failure of COSB were observed during four-point short-span bending tests of HCLT. All the HCLT specimens had higher shear resistance than that of regular CLT with the same number of layer. The difference of the shear resistance between the two strength directions of HCLT decreased as the number of COSB layer increased. In addition, the shear resistance and stress of HCLT can be predicted according the shear analogy theory, and the developed FE models can predict the shear stress of HCLT well. The results presented in this paper can provide fundamental basis for supporting the potential engineering application of CLT panel products fabricated with COSB.