Conceptual study of a flexible high-rise

University of Ljubljana, Faculty of architecture, Ljubljana

Project idea

As the world is changing faster than ever, the idea of flexibility is becoming more and more relevant. Buildings are created for decades or even centuries, economies and societies are on the other hand becoming unstable and variable. The consideration of flexibility in architecture is therefore necessary. That is especially true for high-rises which are becoming an important part of sustainable development. High-rises that are able to adapt to constant changes are going to become an important part of the urban fabric.
With the project Conceptual study of a flexible high-rise, I tried to address this problem by developing a concept of a high-rise with no primary function but rather a framework in which many different programs can be inserted depending on the market demands at that time.

Project description

To better understand the main factors that make a high-rise flexible, a study of flexibility in high-rises is made. 40 high-rises with different structural systems from all around the world are analyzed with the help of 5 parameters.
The 5 parameters:
- NFA: Ratio between leased area and building systems area.
- S/GFA: Ratio between structural area and gross floor area.
- F: Flexibility parameter. The ratio between the area of the largest possible rectangle (most effective geometrical shape for the average activity) that can be drawn inside the floor plan and the GFA.
- A: Accessibility parameter. The ratio between the longest possible distance between a random point on a floor plan and its nearest elevator and the longest possible distance between two points on a floor plan.
- I: Illumination parameter. The ratio between the open periphery of a building and closed periphery of a building.
Parameters are calculated for each high-rise. High-rises are then ranked according to calculated parameters and analyzed - what do high-rises with high scores have in common and also what characteristics do the lowest ranked high-rises share.
Results of the study help determine the 5 main points of a flexible high-rise:
- DOUBLE EXTERIOR STRUCTURE
- FREE PLAN
- PERIPHERAL IN-BETWEEN SPACE
- EXTERIOR BUILDING SYSTEMS
- INDEPENDENCE BETWEEN MAIN ELEMENTS
These guidelines are then applied to the location in Ljubljana, where two multi-use high-rises (HR1 hybrid, HR2 office) are designed. The purpose of defining location and program is to prove, how the high-rise adapts to space and function within the framework of predetermined universal guidelines.

Technical information

The main emphasis was put on a structural system that was meant to enable as much flexibility on a floor plan as possible. The double exterior structural system was developed, which enabled a completely column-free central space. The in-between space was used for building systems (staircases, elevators, MEP) and supporting program that changes depending on a floor function. For the outer exterior structural layer, many different structural systems were considered, and in the end, diagrid was chosen for its lean structural elements. The column-free space in the middle is spanned with a space frame structure which height accommodates all of the horizontal building systems distribution.
Great importance was also put on the concept of vertical circulation which is again situated in the in-between space. Due to regulations, some elements are spanning the full height of the building (fire exit staircases, firefighter's elevator), other circulation elements (open staircases, elevators) are placed on the levels according to needs - levels with greater user capacity (sport court, cinema) have a higher number of staircases and elevators, levels with lower user capacity (apartments) have a lower number of staircases and elevators.

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