The financial viability of a sports stadium is often strongly aligned with how truly multi-use the facility is. Operable roofs are a key aspect of this. Innovative engineering enhances the form, function, and affordability of a sports stadium.
Ben Coxon, Aurecon’s Client Director, Health, and previously China and Hong Kong Country Manager and Building Structures Leader, speaks to some of Aurecon’s experts in the smart engineering of long-span stadia structures; and, in particular, the thinking behind operable roofs.
Ben Coxon: Long-span roof structures require big thinking, in terms of innovative structural engineering; what is your design approach?
Mark Sheldon: You really need to think from first principles and be brave. Designing something that might deflect 500mm under dead l
Garth Rowland: Firstly, you need to understand the architectural and client drivers. Long-span roofs can be created through various forms, some being subtle, some exaggerated; so understanding the feel of the stadium is paramount. Thereafter, you get creative and find structural options that work with this framework without limiting the process; a seemingly bad idea sometimes morphs into the ultimate design!
Tommé Katranas: Constructability plays a key role in the
Cost-efficiency is achieved by choosing a structural system that is speedy and simple to fabricate and is modular in nature with as much repetition as possible. By using beneficial structural principles such as arching effect,
Ben Coxon: What sets apart a stadium with an operable roof from other long-span roof projects?
Mark Sheldon: There is an exponential growth in complexity. The structural design leader needs to fully understand the implications of issues that might be normally considered as ‘someone else’s problem’. He or she will need to work closely with the bogie designers to resolve forces into the structure emanating from issues such as emergency stops, friction in bearings, rail tolerances, panel skew, bogie skew, drive forces,
Ben Coxon: What engineering smarts are typically applied to ensure longevity and ease of maintenance of a
Garth Rowland: Generally, a safety in
Tommé Katranas: Maintenance issues such as corrosion protection of steel elements need special attention. Elements that are not easily accessible should normally be provided with a paint system that has a
Ben Coxon: How does the choice of materials impact design and cost?
Garth Rowland: Whole-of-life decisions are required; more durable materials can incur
Tommé Katranas: The most common material used for long-span structures
The choice of the cladding material also plays an important role. In principle, this should be as lightweight as possible; hence, the use of tensile fabric in many of the new modern stadia.
Ben Coxon: What are the trends in long-span roof structure design that adds to patron comfort?
Garth Rowland: The critical aspect of roof performance is
Mark Sheldon: There is always a conflict for open-air arenas and those with operable roofs, to decide how big the opening should be. This is particularly relevant for projects with natural turf such as Etihad Stadium and Wembley. Too much roof and the grass will require a significant annual budget for turf repairs and replacement. Too little roof and the patrons get wet when it rains. The structural engineer tends to get drawn into things like new ideas for turf growth, and
Tommé Katranas: Providing a structure with a clear, unobstructed view from anywhere within the stadium.
Most new stadia make use of the roof structure to accommodate the stadium lighting, obviating the need for
By ensuring that the natural frequency of the structure is such that no wind induced vibrations are possible, one can prevent any transference to the seating tiers below.
Roof overhangs are becoming increasingly larger in order to facilitate spectator comfort,
Ben Coxon: Where and how do you see operable roofs really delivering value to patrons and the owner?
Mark Sheldon: The project we are currently designing is a classic example of delivering value. Margaret Court Arena is currently a 5 000-seat outdoor venue as part of the Melbourne Park tennis precinct. Its configuration means it can’t be used as a separate venue; so, for about 11 months of each year, it is rarely used. During January, one of Melbourne’s hottest months, it is used for the Australian Open tennis tournament. With its
Tommé Katranas: Financial viability over a long-term is possibly one of the most critical aspects that impact large stadiums today; so a cost-effective structure that is flexible to accommodate different types of events, e.g.
Other considerations include:
Ben Coxon: Wind engineering is fundamental for long-span structures. How can engineers add value in this area?
Mark Sheldon: A wind tunnel analysis is essential, to
Garth Rowland: The Australian wind code was not designed for the variety of stadia roof forms that we see nowadays; and even where it can be applied, the results can be conservative. Wind engineering adds certainty in design loads, which improves the structural understanding and facilitates reductions in steel tonnages from those, based on code pressures. Wind engineering is a prerequisite for
Tommé Katranas: Wind tunnel testing to reflect the realistic conditions can significantly impact the design of long-span structures and, ultimately, lead to significant cost savings.
Ben Coxon: World-class stadiums often have unique and distinctive forms. What are the key drivers in
Mark Sheldon: The
Then, there is the business plan for the venue wherein they will make their money outside of game day. Issues such as conference facilities, parking, corporate areas, access to dining,
Garth Rowland: Understanding the client and architectural drivers. Often, the form of the roof can be entwined in the structural solution leading to an elegant roof solution. Additionally, stadiums tend to define the cities in which they are located; so the roofs become more than a functional requirement at a
Tommé Katranas: World-class stadia need to be functional yet express some form of identity and symbolism related to the country and/ or the region it is situated in.
For the Peter Mokaba Stadium (FIFA world cup stadium in South Africa) designed by Aurecon, the roof’s primary truss is supported off an A-frame, raking diagonally downwards through the roof onto the circular concrete towers in the corners. These corner tower supports represent a strong architectural feature of the stadium, the Baobab tree which is indigenous to the area, with the raking truss support members signifying branches.
Other issues such as environmental impact played a role in defining the form of some of the South African world cup stadia, e.g.
Ben Coxon: Are there sustainable elements that need to be considered?
Garth Rowland: Of course,
Tommé Katranas: Possibly consider issues such as the strategic location of stadium lighting close to the playing field using the roof structure as support (more efficient than pylons) as well as translucent sheeting or cladding, strategically placed to
Mark Sheldon, Technical Director, Aurecon, has
Mark is currently Project Director of the Margaret Court Arena and the new 10 000-seat Southern Stand at the home of the Geelong Football Club based in Victoria, Australia.
Garth Rowland, Technical Director, Aurecon, has experience in structural design and supervision of a variety of structural and
Garth has led the structural and services engineering at Adelaide Oval, the AAMI Stadium precinct works and
Based in South Africa, Tommé Katranas is highly skilled in designing structures using reinforced and pre-stressed concrete, structural steelwork, composite steel-concrete construction, timber and brickwork.
He has been responsible for the design and construction supervision of diverse projects, including bridges, office and residential blocks, leisure facilities, retail buildings, schools, industrial buildings, civil structures and FIFA world cup stadium roofs.
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