Study on in-plane shear failure mode of cross-laminated timber panel

To explore in-plane shear failure mode of cross-laminated timber (CLT) panel, this paper carried out relevant research work from the perspective of stress analysis and combined with the crack morphology of the specimen after planar shear. In this study, the load–displacement curve of the hemlock [Tsuga canadensis (L.) Carrière] CLT specimen was obtained by a three-point bending test or an improved planar shear test, the crack morphology of the CLT vertical layer and the azimuth angle of the crack surface were observed and recorded synchronously. The shear strength values of CLT specimens under the two tests were obtained by corresponding calculation. Then the stress analysis of the CLT vertical layer was combined with the azimuth angle of the crack surface to discuss the failure mode of the CLT vertical layer in planar shear. The results showed that the planar shear strength measured by the three-point bending test and the improved planar shear test was in good agreement, and the results measured by the improved planar shear test were more dispersed than those measured by the three-point bending test; Considering the approximation that the in-plane shear of the CLT vertical layer could be treated as pure shear, the three-point bending test was better than the improved planar shear test; For the vertical layer of 63.3% CLT specimens, the azimuth of the crack surface was near the azimuth of the first principal plane obtained by stress analysis; There were two failure modes in the CLT vertical layer in-plane shear: tension failure and shear failure.