Global Analysis of a Tall Timber- Concrete Hybrid Structure Subjected to Wind Load : A Parametric Study of Different Hybrid Solutions

Sammanfattning:   Tall timber structures have received more attention in recent times as building withtimber contributes to environmental benefits in comparison to other building materials.Timber- concrete hybrid structures have become an alternative as previous investigationshave shown that building tall timber buildings implies complexities with regardsto sufficient stiffness and discomfort for occupants. Thereby, it can be stated that thedynamic properties of such tall buildings, which are partly dependent on the mass andstiffness, are vital for the structural engineers in the early design stages.A parametric study has been conducted in order to evaluate the influence on comfortby changing the material and positions of an increased mass in form of added concrete/TCC- floors in the buildings. The study has been accomplished by simplified numerical3D-models in FEM Design in order to obtain eigenfrequencies and translationaldisplacements. The conceptual models were based on Sara Kulturhus comprised of apillar deck system with two cores positioned along the shorter sides of the buildingproviding lateral stiffness.It has been identified that a pure timber structure of 20- storeys is prone to lift whichindicated that hybrid solutions were beneficial to implement. The results also impliedthat adding mass on the the upper part of a 20- storey building is largely influentialas this action has shown to reduce the accelerations and thereby have a significantlyfavorable impact on the comfort. In contrast, it has been shown that adding massin the lower part of the building has negligible impact on the comfort. Furthermore,the results have shown that the most optimal hybrid solution to counteract swaysis to have concrete in the cores and floors of timber. However, this hybrid optioncontributed to most environmental impact, implying that other options with moretimber are more suitable from an environmental perspective. Additionally, it has beenestablished through the results that timber- concrete composite floors do not differremarkably from pure concrete floors in regards of the dynamic response related tocomfort with the thicknesses used in this thesis.Investigating in only one geometry of a tall building and not adapting dimensionsto each case is a simplified approach which, in regards of the ISO- criteria, can beconsidered to fail at capturing the general behaviour of tall timber- concrete hybridstructures accurately, and is therefore not suggested for future studies. While on thesubject of future research projects, the complex relationship between the mass andstiffness should be studied when changing one parameter at a time.Keywords: Parametric study, Dynamic response, Comfort, Tall timber-buildings