Bending performance of adhesive-free cross-laminated timber panels fabricated with fast-growing Chinese fir

To effectively utilize China's abundant fast-growing forest resources for the manufacturing of engineered wood products (EWPs) and reduce the environmental impact induced by adhesives in EWPs, this study developed nailed cross-laminated timber (NCLT) using machine-graded fast-growing Chinese fir laminations, with wooden nails as the fasteners. Four-point bending tests were conducted on 28 NCLT panels. The failure modes, bending strength, and stiffness of the specimens were investigated. The parametric analysis was carried out based on the validated finite element analysis of NCLT panels. The results show that the failure mode of NCLT panels differs from the brittle failure of cross-laminated timber (CLT) panels, demonstrating a better plastic deformation capacity. The bending strength and stiffness of NCLT panels ranged from 8.67 to 12.33 MPa and 5.90 to 13.95 kN<middle dot>m2, respectively. Moreover, both the bending strength and stiffness of the NCLT panels showed a positive correlation with the diameter and quantity of wooden nails. The mechanically jointed beam model can accurately predict the bending stiffness of NCLT. Through the rational arrangement of the laminations and wooden nails, NCLT has the potential to serve as a substitute for CLT.