Mechanical properties of ply-lam cross-laminated timbers fabricated with lumber and plywood

Abstract

The mechanical properties of four ply-lam cross-laminated timbers (CLTs) containing a plywood layer were compared with those of glued laminated timber (GLT) and CLT. The bending, out-of-plane shear, and compression strengths were highest in the GLT, followed by the ply-lam CLTs and CLT. The modulus of elasticity (MOE) values for the three studied ply-lam CLT samples were 1–2.5 GPa higher than GLT; however, the modulus of rupture (MOR) of all ply-lam CLTs was 7.3–18.8 MPa lower than GLT. The length of the plywood product is 2,440 mm, and longitudinal bonding is required to manufacture ply-lam CLTs of length > 3 m. The prediction of bending capabilities by shear analogy was compared with the bending properties when joints were included. The performances of all the pilot-scale ply-lam CLT samples exceeded the predicted bending performance standards for MOE (10 GPa) and MOR (30 MPa) All samples exceeded 10 GPa and 30 MPa, based on projected and experimental data.