Behaviour of cross laminated timber elements with openings at out-of-plane loading conditions

Sammanfattning: The use of cross laminated timber (CLT) is expanding, its use is relatively new and universal design standards are lacking. One situation for which no universal design standard exists is that of a CLT plate element with an opening. A grillage method has been proposed as a convenient method to design such plate elements. The grillage method consists of analyzing a beam grillage model in terms of bending moment, shear force and deflection. This thesis examines the grillage method and compares it to corresponding finite element (FE) models. The FE models are modelled in Abaqus with three-dimensional shell elements using a composite layup tool in order to model the individual layers of CLT. Throughout the investigations three CLT compositions with differing layer thicknesses are used. Hence, cross section composition is included as a parameter in the study. Different methods to evaluate CLT beams are examined and applied to the grillage model; Gamma method and Timoshenko beam theory. For various opening geometries results from grillage models are compared to results from FE models. In the FE models results are extracted from paths coinciding with the geometry of the beams in the grillage models. The results show that the choice of beam theory does not impact the results from the grillage model significantly. When compared to FE models the grillage models give generally higher values for bending moment, shear force and deflection. Certain combinations of opening geometry and cross section composition causes a large discrepancy between the grillage model and the FE model.