New canopy roof transforms Olympic Sydney tennis venue

Australia’s first cable-tension stadium roof

Our structural engineers created a solution that enclosed the stadium and maintained the integrity of the original design, engineered by us in 1998. We used the circular stadium and existing perimeter roof structure to cleverly re-provision support to the rear of the seating bowl to provide the supporting structure for the new roof.

This simple construction solution “tricked” the existing raker beams into believing that nothing had changed, and is an example of sustainable, structural-led repurposing and reconfiguration.
By designing a lightweight, self-resolving cable tension roof, we minimised the need to strengthen the existing supporting frame and removed any need for new foundations or foundation modifications, as roof force loads were not transferred to the bowl.

Roof geometry was form-found by us using steel cables to create a self-supporting roof. The fabrication geometry and installation cable pre-stress was provided to the fabricator digitally, with no paper structural drawings delivered. Due to the project’s innovative design and short time frame, cables and fabric were pre-ordered directly from the design. 

All the connections were designed and detailed in 3D, then provided to the shop detailer to complete the fabrication model. With the shop detailer working alongside our team in the Sydney office, we streamlined the process from design to fabrication.

A simple solution of vertical steel bracing using Macalloy bars was applied to the bowl structure, bringing the seismic performance of the stadium up to current code provisions.

Natural ventilation allows year-round use and protection against fire

Protecting athletes and spectators from heat was the purpose of the project. Through detailed CFD analysis, our environmental engineers delivered a system that would maintain a comfortable environment under the new roof, protecting players and spectators from the sun. Our ventilation solution included a series of four-metre-tall folding doors around the bowl to introduce fresh air into the venue and remove hot air through the central roof oculus. 

The design created a smoke exhaust when the doors are closed. With the change from an open to a semi-enclosed/enclosed venue, this significant structural alteration needed to be assessed by our fire engineers to identify potential hazards. 

They found that the natural ventilation of the structure would clear smoke without the need for exhaust systems, and a detailed assessment of the steel frame’s response to fire showed that protecting the structure would not be necessary. 

The fire engineering team worked closely with our structural, fire services, lighting and mechanical engineers to reduce the visual impact of installed safety devices and fittings to minimise the impact of fire safety upgrades. Our detailed fire strategy approach accelerated approvals in compressed timeframes.

In extreme heat, temporary air-conditioning units are positioned around the court to keep players cool, with spectators cooled by permanent ‘impulse’ drum fans located underneath the fabric roof.

For Tennis NSW and its spectators, the arena still needed to feel like an outdoor venue. Using a translucent PTFE roof fabric allowed natural light to flood the venue and illuminate the space. The perimeter doors open to reveal the Sydney skyline, reinforcing the sensation of being in an open-air venue.

With the doors closed, the arena transforms into a world-class venue for Netball NSW’s professional teams, NSW Swifts and GIANTS Netball, who have called the arena home since 2020.

One-year project possible through digital design 

Taking advantage of significant analysis and planning, our team determined a workflow to ensure project delivery. 

Using advanced digital tools (Rhino, Grasshopper, Geometry Gym and GSA) to complete the design within three months gave us maximum time for construction. Engineering the canopy was complex – the tension roof had to retrofit to the stadium’s circumference and existing services. 

The designs were kept within a secure 3D environment, with automation and parametric modelling hastening design reviews and alterations. The digital collaboration with designers, architects, contractors and builders supported a comprehensive workflow which saw the roof completed on schedule and to an award-winning standard.