Experimental investigation on the effect of openings on the in-plane shear strength and stiffness of cross-laminated timber panels

The high in-plane shear strengths of cross-laminated timber (CLT) make it a good candidate for use as shear walls in buildings in areas of high seismicity such as Japan. One important aspect of CLT walls, and one that is presently poorly understood, is the influence of openings on the in-plane shear carrying capacity. The main purpose of this paper is to experimentally evaluate the effect of openings on the in-plane strength and stiffness of CLT panels with openings. In this study, 24 CLT panels were tested using a diagonal compression test configuration. In particular, they were three identical replicates of eight CLT panels. One of these eight panels was a solid panel, while the other seven panels had openings with different sizes and aspect ratios. The results showed that the panels with openings with the same area but different aspect ratios had different failure directions and reduction factors for panel shear strength and stiffness. Panels with rectangular openings with different orientations relative to the panel’s major and minor shear direction had different failure direction and reduction factors. In addition, the effect of openings on the reduction of initial stiffness for CLT panels was found to be greater than their effect on the reduction of shear strength. This paper's findings will help clarify the reduction in strength and stiffness of CLT panels with openings, which is an important aspect of the seismic design of buildings.