International Council for Research and Innovation in Building and Construction, Working Commission W18 - Timber Structures
Cross laminated timber (CLT) has become a well-known and widely applied two-dimensional, engineered timber product worldwide. It constitutes a rigid composite of an odd number of orthogonal and glued layers. Focusing on a single glued node loaded in plane in shear and composed of two crossed board segments and the adhesive layer in-between, in principle three types of shear mechanisms can be distinguished: mechanism I "net-shear" (shearing perpendicular to grain), mechanism II "torsion" and mechanism III "gross-shear" (shearing parallel to grain). In fact, while having generally accepted values for the resistance against mechanism II and good estimates for mechanism III the resistance against "net-shear" (mechanism I) is still in discussion. In spite of numerous investigations on nodes and on whole CLT elements in the past, a common sense concerning the test procedure, the consideration and handling of distinct influencing parameters and the quantification of the shear strength are open. We focus on the in plane shear resistance of single nodes according to mechanism I. We (i) propose a test configuration for reliable determination of the shear strength, (ii) determine the shear resistance in case of shear loads perpendicular to grain, (iii) discuss influences of some parameters on the shear strength of single nodes, and (iv) give a brief outlook concerning the resistance of CLT elements against shear loads in plane.