Efficiency of new high capacity self-stabilising modules in mid-rise residential buildings

Abstract

The aim of this thesis is to investigate and quantify the efficiency of high capacity self-stabilising modules in mid-rise residential buildings. These modules have a higher stabilising capacity than modules that are currently being used in the Netherlands and other countries and can therefore be used for more storeys without requiring an additional stabilising structure such as a concrete core.
In the first part, reference projects and case studies are looked at to get a good understanding of the current applications in The Netherlands and the United Kingdom. After analysing four case studies, an assessment is done on the functional efficiency, structural capacity and environmental impact of these modules. By doing so, the load-bearing structure of self-stabilising modules that can be used at a greater height can be identified. Design variants can now be drafted with different bracing configurations, which are later verified on strength and stability requirements. To effectively design a suitable braced frame, it has been researched what the displacement components for braced frames are. This has been done for simple frames without eccentricity as well as frames including eccentricity. Apart from single-cross frames with a relatively large span, double-cross frames are also looked into due to their increased stiffness.
As part of the total structure of the building, a design for the foundation as well as the inter-module joint, which is required to be demountable, has been made. These parts of the design are required to calculate the horizontal displacement during lateral loads.
A structural assessment is done on the stabilising capacity of each variant at 8 storeys. The design adjustments that are required to further increase the number of storeys up to 10 are looked into as to see whether or not an efficient structure can be maintained. It turns out that each design variant requires adjustments that reduces the efficiency. These changes are the result of a large increase of braced span, resulting in either inefficient use of beam profiles or a too large length when there is more than one braced span along the length.
Apart from a structural assessment, the functionality and environmental impact of the design variants has been analysed as part of the overall efficiency of the modules. The functional assessment includes several criteria such as wall-to-floor area and space efficiency factor. Using the required material use in partition structures and load bearing elements, the environmental impact is calculated, resulting in values for the embodied energy and embodied carbon per square meter in each design variant. Since the differences between the design variants are relatively small, they are also compared to four case studies that were done before.
On the basis of the results of this research, it can be concluded that self-stabilising modules can be constructed with different possible bracing layouts and an efficient load-bearing structure up to 8 storeys.