Lateral Stabilization of CLT Buildings - Modelling approaches

Abstract: Cross-laminated timber (CLT) is an environmentally positive building material with high stiffness and load-bearing capacity. In combination with a low self-weight, CLT is a beneficial material to use for the load-bearing structure of high-rise buildings. In this project, the lateral stabilization of a CLT building subjected to a wind load is analysed through several modelling approaches. The effect of modelling choice is investigated through predicted stiffness (displacement), internal force distribution and reaction force. The modelling process considered in this work is divided into three parts. First, a single CLT panel is modelled as a truss and as a shell, respectively. The models are compared in terms of global horizontal displacement. The truss model consists of horizontal and vertical rigid bars and a diagonal spring. The spring stiffness is calculated to represent the stiffness of the CLT panel. Both shear deformations and bending deformations of the panel can be included. For wider panels bending and local effects are less decisive, and the shell model and the truss model have more similar results. Applying a vertical restriction at the top of the shell model makes the agreement between the two approaches, the shell model and the truss model, better. In the second part, multi-storey models are built up by the single panels from part one. Shell models are compared to truss models, both including and not including a reduction for bending. The panels are connected to create different configurations with varying heights and lengths. The global horizontal displacement of the multi-storey models is of main interest. Applying a restriction for vertical displacement to the shell model makes the horizontal displacements between the models better coincide. The more slender the models are the greater is the difference in displacement between the truss and the shell model. This due to the greater influence of bending for more slender models. The third part is a further investigation of the shell model. A full-scale gable of five storeys is modelled including door and window openings. Different subdivisions of the gable are investigated both including and not including a self-weight. The placement and stiffness of hold-downs as well as the stiffness of line hinges are investigated. The horizontal displacement, internal forces and reaction forces are all affected by the inclusion of the self-weight. A higher hold-down stiffness results in higher reaction forces and a smaller displacement. The line hinges have as well an effect on the displacement of the gable. The subdivisions of the gable are modelling approaches, especially affecting the distribution of internal forces in the gable. The models are developed through simplifications of the reality and the modelling approaches are based on these properties. The modelling choice has a considerable effect on the result and the coinciding of the models. Limitations are made and the study leaves room for further developments of the subject and its models.