Study on the interlaminar shear properties of hybrid cross-laminated timber (HCLT) prepared with larch, poplar and OSB

Abstract

In order to better understand, and ultimately improve, the interlaminar shear performance of CLT, this paper explores the influence of three different laminates—larch, poplar and OSB—as transverse layers on the interlaminar shear performance of CLT. The results showed that, although larch, poplar and OSB have little difference in overall density, the interlaminar shear strength of CLT was significantly affected with the use of each as the transverse layer. The interlaminar shear strength in the major direction of CLT prepared with three different materials as transverse layers is: 4.18 MPa (Larch - Poplar - Larch), 3.52 MPa (Larch - Larch - Larch) and 2.71 MPa (Larch - OSB - Larch). The interlaminar shear strength in the minor direction of CLT prepared with three different transverse layers is: 0.91 MPa (Larch - Poplar - Larch), 1.11 MPa (Larch - Larch - Larch) and 0.22 MPa (Larch - OSB - Larch). The interlaminar shear failure modes of the three CLT specimens are different: in the major strength direction, when larch was used as the transverse layer, the interlaminar shear failure mode was rolling shear failure of the transverse layer. When poplar was used as the transverse layer, the interlaminar shear failure modes of CLT were transverse layer shear failure and surface layer shear failure. When OSB was used as a transverse layer, the interlaminar shear failure mode of CLT was the internal shear failure of OSB. In the minor strength direction, the interlaminar shear failure mode of each of the three CLT specimens starts from the unsized gap on the side of the bottom laminate element, and the typical bending failure mode occurs in the transverse layer. CLT prepared with poplar as the transverse layer has lower density, but better interlaminar shear performance in the major strength direction. The interlaminar shear strength in the strong axial direction is affected by the structure of the transverse laminates, and as such homogeneous laminates are more suitable for use as transverse laminates.