Adopting triple-bottom-line considerations to assess the success of high profile stadia development projects has increased in the last decade.

Such assessment is commendable and to be nurtured, however, achieving a “balanced” set of objectives should not be at the expense of a venue’s primary purpose: hosting elite-level sport and accommodating large crowds.

The showpiece of the Queensland Tennis Centre (QTC), the 5500-seat Pat Rafter Arena has achieved triple-bottom-line outcomes without compromising the facility’s ultimate goal – to host large-scale tournaments and capture the atmosphere of the spectacle while providing excellent player and patron amenity.

Sinclair Knight Merz (SKM) provided structural engineering services for the QTC as part of an integrated team. The stadium was designed by collaborating architects HOK SVE (Populous) and Mirvac Design. The delivery team also encompassed Mirvac Construction and the state government-owned authority Stadiums Queensland.

The centre was developed to host the Brisbane International, a major lead-up tournament to the Australian Open. The recently completed facility is also the home of the Queensland Academy of Sports tennis program, and is anticipated to be a popular multipurpose venue for other sporting and speaking events.

The project’s success demanded innovation in building design, construction, safety and sustainability, particularly in contributing to the stadium’s delivery on time and within budget.

These attributes also had to enhance, rather than compromise, the success of the project as an outstanding sporting venue.

Stadium roof: Balancing sustainability with constructability

In recognition of the hot and humid conditions that can be experienced during the Queensland summer and the distress this can have on players, the QTC features the world’s first fixed roof for an outdoor tournament court.

In reference to the historical “Queenslander” architectural style that sought to deal with the region’s climate, the stadium’s roof is open at the sides and welcomes natural light to the centre court via its translucent polytetrafluorene (PTFE) fabric roof. While the open sides also provide natural ventilation, raising the centre of the PTFE fabric roof allowed further ventilation to the players and spectators as it allows hot air to escape, creating a chimney effect within the stadium.

The remaining (unraised) section of the stadium’s roof features traditional cladding and a unique sandwich metal roof panel, incorporating a ceiling system that provides an acoustic barrier to minimise sound reverberation and break-out noise.

Dynamic analysis

Various stadia around the world have been designed and built, only to find they have a vibration issue due to rhythmic excitation from crowds during sporting events and concerts. Such vibration issues are not easily or inexpensively rectified.

Stadium dynamics places significant risk on the venue’s success as excessive vibration impacts the public attending events, which can result in restrictive event management practices and revenue loss.

The project team applied Finite Element Analysis (FEA) techniques to the QTC to predict crowd-induced vibration and optimise the stadium’s design.

Construction efficiency

Design efficiency to minimise material use is critical to delivering value, and in the case of the QTC, to meet the fixed deadline.

The QTC’s light and elegant roof structure incorporates fabric sections that not only enhances the stadium aesthetically, but is cost-effective, uses fewer materials, and was constructed more easily and efficiently than a traditional roof structure.

For example, trusses were constructed on the ground next to the stadium and craned into place, which ensured a quicker and safer roof erection and allowed trades below to continue concurrently.

The QTC design allowed the roof and grandstands to be constructed independently.

Other design decisions that enabled a quicker, safer construction included maximising off-site construction, using steel and pre-cast concrete materials, designing simple connections for efficient steelwork placement and maximising member lengths and grid spacing to reduce lifts and connections.

Sustainability

By making decisions early about key design elements and operational features, the QTC has successfully reduced its impact on the environment and responded to existing ecological conditions.

To ensure the comfort of both the players and the 5500 spectators in the Pat Rafter Arena the design accounts for diverse climatic conditions, including solar access, wind, rain and humidity.

Natural ventilation and daylighting

The “open air” stadium design allowed for a facility that maximises natural ventilation, lighting and weather conditions to provide thermal comfort to the players, officials and spectators within the arena.

The open sides maximise cross ventilation, while a raised central fabric roof (also with open sides) enables venting of escaping hot air.

Covering about a third of the roof area, the translucent fabric roof is positioned over the centre court to maximise daylight.

The wind modelling also considered comfort conditions for players, spectators within the arena, function decks and pedestrians around the podium. It identified ways to improve the comfort conditions, including adding landscaping and enclosing some structural elements.

Sustainable material selection and use

Ecologically sustainable material was selected where possible to minimise building emissions and ecological impact. Long-term costs such as waste management, resource consumption and life cycle of materials were also considered.

Concrete was specified with a minimum of 20 per cent portland cement replacement by using industrial waste (ie flyash/slag) to reduce the embodied energy and associated emissions by up to 20 per cent.

The majority of the concrete structure was constructed using post-tensioned concrete which reduces the overall quantity of concrete and steel required when compared to traditional reinforced concrete slabs.

Noise management

Minimising noise to the surrounding residential community whilst ensuring that noise does not excessively reverberate within the stadium is a unique challenge to enclosed sports and leisure facilities.

This was achieved through the high performance engineered acoustic roof/ceiling panel system, which is manufactured from wheat or rice straw; a renewable resource which is a by-product of agriculture.

During this unique manufacturing process, no water or gas is used. The ceiling panel system does not contain any additional chemical binders, formaldehyde or volatile organic compounds (VOCs).

Rainwater harvesting

Due to drought, water usage had to meet government-set restrictions, and where possible, it had to be conserved via collection and re-use.

Water collected from the main stadium roof and the external courts via syphonic and gravity-fed systems to an underground tank is used to irrigate the facility’s landscaped areas and grass and clay tennis courts.

Meeting multiple demands

The purpose-built A$80 million QTC successfully addresses the multiple demands of innovation in building design, construction, safety and sustainability.

Importantly, the facility performed to a high standard when hosting its inaugural international tournament in January 2009, attended by 65,000 spectators over eight days.

Acknowledgements

Sinclair Knight Merz (SKM) provided structural engineering services for the QTC. The facility was delivered through strong collaboration with architects Populous and Mirvac Design; Mirvac Construction; and the state government-owned authority Stadiums Queensland.

© Sinclair Knight Merz
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