Anna Meares Velodrome

Circle Work

Opting for a membrane roof – primarily to allow diffuse daylight in – left the way open for structural steel to star in the show.

The latest addition to the Sleeman Sports Complex in the Brisbane outer-suburb of Chandler, the Anna Meares Velodrome – named after Australia’s most successful track cyclist and the most decorated female track cyclist of all time – was purpose-built by Stadiums Queensland to host the Gold Coast 2018 Commonwealth Games  (GC2018) track cycling, and then to provide a lasting legacy facility.

Its predecessor in the Complex – a 333-metre outdoor velodrome made of concrete – staged the 1982 Commonwealth Games track cycling events, from which Australia bagged seven gold medals (only to be eclipsed by the 2018 gold medal tally of 10).

Cox Architecture project director Richard Coulson says the client brief for the new velodrome stemmed simply from the track needing to be enclosed. “They of course already had an outdoor track so wanted this one covered,” he says. “A premium track was the centrepiece of the new velodrome so protection of that from the elements, and also to control the wind and temperature conditions that can affect cycling performance, was paramount.”

The architects’ accomplished history of sporting facilities, which includes the Gold Coast Aquatic Centre (also built for GC2018), didn’t hurt its chances in the velodrome’s design competition, which it won in 2014.

The velodrome is the latest in a long line of Cox Architecture sporting projects including the emblematic AAMI Park (Steel Profile 108) and Coulson acknowledges the practice has a signature, of sorts. “We have national expertise in sporting projects stretching back 40 years to Bruce Stadium in Canberra all the way to our current work on the 25,000-seat North Queensland Stadium in Townsville, which will be home to the North Queensland Cowboys, but our local studios bring their own nuances to projects. There is a history of white buildings, but that’s not necessarily a Cox starting point. With the velodrome we set out to make a building with multiple individual strengths. We knew that over time there would be value in all parts of the building and in making the space really powerful.”

Coulson says the design was also deliberately informed by the dynamics of the primary sport played out under it. “The roof was very much influenced by the act of cycling and influenced by the shape of the track. You can see in the plan view that it has a circular sensibility and, in the sectional and elevation views it shows a fluidity in the space. We describe the velodrome as quite kinetic – it has those inclined walls on the perimeter which spring-out above to allow for stage-able seating.”

Once the building’s footprint was established, Cox and its partners – engineers Arup and building contractor Watpac Construction – sought to create the most efficient, economical and compact structural system possible and steel was always going to be the material to deliver it.

“It would be possible to use some types of laminated timber instead, but we had a number of internal footprint and envelope considerations that required the relative fineness of steel, so we discounted other materials,” Coulson explained.

A planar radial truss system was settled on, for its efficiency and buildability. “We contemplated a variety of different span solutions including portals and non-radial members but to reduce it as an element in the landscape and for the sake of economy we were trying to make the smallest building possible,” he says. “Other construction techniques would have left a much bigger footprint and volume than we required. Modular steel trusses or portal-style solutions can appear quite light, but those roofs are much higher than we have achieved.

Watpac Construction design manager Anthony Leonardi agreed that early consultation was vital when coordinating so many major parties. “We get involved with the architect and engineer on the detailing as early as possible and pride ourselves on rapid engagement of the shop detailer – we engage the drafter even before we get a steel fabricator on board!”

The construction sequence for the structural steel roof frame was geometrically and logistically challenging, Leonardi explains: “The first thing erected was the main ‘doughnut’ in the centre that we call the oculus, which is a fully framed truss structure that sits about 7 to 8 metres deep, with tension rods between CHS chords. It was self-supported on nine Favco 750 crane towers that allowed us to do the sub-structure at the same time. We then proceeded to temporary support for the external columns and started dropping in the 16 main radial trusses that link the external columns to the oculus’s frame.

"We chose to use fillet-welded saddle plates on site rather than bolted splices. This meant that major elements of the roof structure could be lifted in, positioned on welded saddle connections and fillet-welded, providing flexibility in terms of tolerances.

“Even transporting some of the structural steel elements to site was a major task, with some of the truss sections being 10 or 11 metres wide. Beenleigh Steel, the steel fabricators, even had to remove some sections of their front gate and fence to get the trucks out with the large steel sections on them and had to be transported with a police escort in the middle of the night, given the oversized loads.”

Arup principal Ian Ainsworth says the structure’s success hinged on early collaboration. “The form of the building, the basics of the roof structure and how it would be built, were developed in the first two weeks of the job during the design competition,” says Ainsworth. “We had a series of workshops and debated which ones worked and didn’t from everyone’s viewpoint before settling on the one that was built.

“We take the same approach on most jobs, which is to get in early and work with the architects not only to deliver their vision but also to help shape the preferred form so that we don’t end up in a situation where someone comes up with a shape in the absence of any engineering input and hands it to us saying ‘just make it work’.

“We worked with Cox to develop the building’s form which was all about trying to minimise the volume because it had a very tight budget, yet do it in a way that still provided the flexibility to accommodate additional temporary seating in event mode, and a range of indoor sports and community uses.

“The roof shape was driven by the plan and the volume. We ended up with an elliptical roof plan with a hyperbolic paraboloid form that is concave in one direction and convex in another – a saddle shape – albeit a very large-radius one.

“The inclination of the walls, which effectively taper back in, was once again a response to keep the overall volume of the building as small as possible. From a structural point of view, the inclined perimeter wall allowed us to match up inclined columns with vertical tie-downs.

“This bi-pod-type arrangement around the outside allowed us to deal with and take advantage of the roof having a bit of shape to it, which it does in this case, arching in one direction and acting like a catenary cable in the other. Those shell-type actions in the roof give some large thrusts around the outside that are resisted by these pairs of inclined columns and vertical tie-downs.

“Because we were sinking the cycle track into the side of a hill and we were on quite good ground, we were able to take those thrusts that were coming from the roof shape down into the ground relatively simply and economically. That then meant we could take advantage of the roof shape and design it with some shell action and still do it in an economical way.

Ainsworth says another big driver for Arup was the client preference for the venue being delivered reliably and quickly by local Queensland subcontractors. “So we designed the roof in a way that it could be readily fabricated from available straight steel members, rather than having lots of curved members or three-dimensional trusses that would have been more complicated to weld and transport,” he says.

“The roof structure is mainly made from planar trusses because they are a regular two-dimensional truss. You just lay it flat, weld it, tilt it up, and it’s ready to transport and erect. The roof was also configured so that the temporary central supports could be located in the infield area away from the track and the complex concrete bowl, and substructure works. This allowed roof erection to start early and to be carried out in parallel with the concrete works below. Through the use of parametric design and models shared by engineer, architect and shop detailer, the apparently complex geometry was also rationalised and controlled.”

The completed minimalistic structure allowed Cox to achieve its goal of delivering an architecturally striking and functional project for a modest outlay. “We had a comparatively tight budget – about $60 million for a track under a roof which represents extremely good value considering the London Velodrome, which has a similar span, was a $300 million project,” Coulson says. “We were able to produce a solution that maintained great design quality and everyone is delighted by it. The client has achieved popular engagement through its multi-functionality and it is producing great race times.

“There are plenty of ways to span 120 metres in steel but we wanted to do it in a way that was an impressive response to the space because the timber track is such an amazing thing. It’s like an enormous piece of furniture, and we wanted the roof to reflect that expressive quality and have that kind of craftsmanship in steel.

“We wanted to make a valuable contribution to the space that honours the riders’ performance and provides drama for the spectators. I think we have achieved that and it’s a result that I don’t think will diminish over time.”