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Flinders Uni Student Hub, Adelaide: Offsite prefabrication of the steel frames used at this university student hub allowed for rapid construction time and cost savings.
Architect
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The design of the Flinders Uni Student Hub required an architectural vision that would achieve multiple objectives. These included the formation of a central hub for a range of activities including student services, dining, entertainment, functions, meeting places and spaces for both private and collaborative learning.
The project took the form of four main components: a four-storey office and administration centre; a three-storey extension and redevelopment of the central Union Building and Mall; an external plaza and landscaped amphitheatre; and a canopy to the southern side of the existing Library building.
Of significance is the fact that the steel specifications applied to the design ensured that 98% of the steel elements were sourced from Australian manufacturers.
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The Mall building needed to provide a transparent link between the internal and external plaza space through the extensive use of glass. Both precast concrete and structural steel options were investigated but the use of structural steel framing proved superior in achieving a relatively lightweight structure with minimal visual obstruction. It was also important for the general circulation spaces to remain as column-free as possible.
In order to achieve these objectives, three-storey steel portal sway frames were used that respected the three-dimensional grid utilised in the design of all of the original buildings at the campus. The frames comprised large, square hollow section (SHS) columns with a similar roof beam to form the single pitch roof slope. Composite precambered 700WB floor beams were selected to clear span the full-width suspended floors to minimise the structural beam depth.
The bases of the portal frames were designed as fully fixed moment-resisting connections to limit the horizontal sway of the building while resisting either lateral wind or earthquake loads. Design deflections were limited less than 30mm over the 12m height of the building to minimise the risk of damage to the relatively brittle glazed façade. Intermediate 360UB floor beams were designed as unpropped sections to support the metal deck formwork between the main frames.
The portal frames enabled the narrow east-west dimension of the building to remain uninterrupted by vertical bracing, which was subsequently confined to discrete locations in the north-south direction. The frame connections were all designed to be bolted on-site to facilitate ease of transportation and erection.
Structural steel also proved to be the most appropriate construction material for the complicated geometry for the main stairs, which needed to be as lightweight as possible to achieve the significant spans and overhangs.
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The canopy was designed to provide a two-storey-high link between the new Mall Building, the existing library and the facilities on the eastern side of the campus. The canopy features three curved vaulted roof sections to reflect the roof structure of the library. The canopy is clad in translucent panels to allow natural light to the walkway below. Stormwater drainage pipes were cleverly concealed within the circular hollow section columns.
Overall, the use of structural steel enabled the achievement of the structural, architectural and aesthetic objectives. The result is an economic, slender, transparent and lightweight structure that was delivered within a tight construction program and on a site with significant constraints.
The project was not formally assessed by the GBCA, but the use of steel enabled a reduction in the mass of materials used. The lightweight nature of steel when compared with concrete construction for example, resulted in an overall reduction in mass and embodied energy that further reduced the size and extent of footing and lateral bracing systems.
There was also a reduction in reinforcement requirements and concrete volumes for floor slabs within the Mall building, which provided added benefits in relation to transportation requirements and the inherent minimisation of greenhouse gas emissions.
The use of steel in the project will also allow for deconstruction and reuse. Although the building has been designed for a life of greater than 50 years, when it is no longer considered to be useful, the steelwork components may be readily deconstructed by unbolting connections, allowing the framing to be either reused or recycled.
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