The Netherlands is currently facing a severe housing shortage. As the supply of new homes cannot keep up with demand, housing prices have increased significantly. At the same time, the construction sector must comply with strict climate requirements to reduce CO2 emissions. Timber is a construction material with low carbon emissions, but building higher than 6 stories traditionally requires a concrete core or CLT, which significantly increase CO2 emissions and construction costs. To fill this gap, the WoodCore consortium was founded to develop a low-emission and affordable building concept. This thesis aims to study the lateral stability and stiffness system of this concept, which consists of a timber exoskeleton, a braced timber core, and timber frame shear walls. The main objective is to investigate, through a parametric study, how these various stability systems influence the horizontal deflection of the building and how they can be optimized.

To achieve this objective, a parametric workflow was developed using the finite element software SCIA Engineer. Models of the timber building concept were created and exported to XML files. By modifying these files with a Python script and running them using SCIA OpenAPI modules, many different parameter configurations could be studied. To reduce the total computational time for thousands of configurations, the workflow was expanded with a surrogate model. This mathematical model mimics the finite element analysis results, allowing for a significant expansion of the studied parameter configurations.

With this approach, the influence of seven parameters on the horizontal displacement was investigated across variants with a varying number of stories and diagonal layouts. Parameters for both the exoskeleton and the braced core included the dimensions of the timber diagonals and columns, and the axial stiffness of the diagonal connections. Additionally, the stiffness of the timber frame shear walls was studied. To evaluate these parameters, a local sensitivity analysis (One-At-a-Time method) and a global sensitivity analysis (Variance-based Sobol method) were performed. Furthermore, the economic and environmental influence was studied using a material and shadow costs comparison.

The analyses show that the exoskeleton has a significantly larger influence on the horizontal deflection than the braced core and timber frame shear walls. Furthermore, the dimensions of the diagonals and the axial stiffness of the connections have a greater influence than the column dimensions. The global sensitivity analysis also reveals that parallel linked parameters interact with each other, meaning their influence is interdependent. Although the influence of each parameter is highly dependent on the chosen parameter ranges and baseline geometry, the number of stories does not necessarily influence the results.

Finally, the cost-effectiveness analysis indicates that changing the diagonals and connection stiffness is highly effective regarding material and shadow costs. Although the braced core has a lower influence on the lateral stiffness than the exoskeleton, the cost-effectiveness of these parameters is comparable in both systems. Based on these results, it can be concluded that optimal parameter configurations for material costs are characterized by minimal column dimensions and low stiffness of the shear walls, and that the design should focus on the diagonals and axial connection stiffness for the global lateral stiffness of the building.
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