Possibilities of timber high-rise

Abstract

Sustainability is an important aspect in the construction industry nowadays and therefore timber is interesting to use as it is considered a sustainable building material. With the development of mass timber engineered products such as glued and cross laminated timber, there are more and more possibilities to use timber as a structural element, but this material is not yet widely used in high-rise buildings. Recent research has shown different aspects to take into account when using timber. Due to the lightweight, high flexibility and strength, attention must be paid to the dynamic behaviour and the high horizontal deflections of the top levels of the building due to wind. A parametric model is used to generate the structural model, which enables you to easily change certain parameters to gain a quick insight into the consequences of these changes on the behaviour of the structure. The model is developed in the program Autodesk Dynamo, where a plug-in developed by the company Arcadis is used to connect Dynamo to a FEA application called RFEM to be able to check the generated structure on relevant criteria. The parametric model is able to design a building which has certain dimensions and lateral stability systems which can be changed. It is chosen to implement lateral stability systems consisting of shear core(s), a diagrid and a tube, which can be used either independently or combined. The connections between the elements cannot be modelled with a finite stiffness using the Arcadis plug-in. Therefore, several assumptions had to be made to encounter for the characteristics of the connections. The Young’s modulus of the structural elements are modified to take into account the stiffness of the connections and openings in surfaces if present. To check if the parametric model gives satisfying results, a case study is performed on the BrockCommons Tallwood House. This showed that the parametric model gives satisfactory results. A parametric study is performed to check the possibilities of timber high-rise regarding maximum building height in The Netherlands. An office building with a width of 32.4 metres, a depth of 28.8 metres with a specific floor plan and connection characteristics is used. Optimal configurations regarding compressive and tensile resistance of connections between structural elements are resolved using MATLAB and the reduction of Young’s modulus of the elements is determined using the specific connection characteristics. The connections used in the parametric study are compared to commonly used connections regarding strength and stiffness. Furthermore, an insight is given on the influence of the stiffness of the connections on the structure. The maximum building heights are investigated for stability systems consisting of either a shear core, diagrid, tube or a combination of 2 stability systems. Results show that a 4-storey diagrid system with infinite stiff connections can reach the greatest height of 187.2metres. No additional measures had to be taken to ensure that each structure complied with the maximum acceleration limit for office buildings. Finally, a comparison
is made between the stability systems with regard to total timber volume and steel mass usage.