A significant driver for this project was for the provision of a world-class, architecturally designed cycling venue for the staging of the Gold Coast 2018 Commonwealth Games Cycling events.
The Anna Mears Velodrome roof is a saddle-shaped form, slightly oval in plan and draining to the two low ends. The roof was originally conceived as a metal deck roof supported on 20 radial trusses spanning from guyed perimeter columns to suspend a central “oculus”. Both architect, Cox Rayner, and builder, BESIX Watpac, were keen to explore the use of a fabric alternative. The architect was interested in the freedom of form and natural light transmitting possibilities. The builder had concerns with the complexity of fitting purlins and sheet metal to a truss layout and geometry that did not suit the surface falls. Fabric also offered program advantages. MakMax Australia’s scope was to design, engineer, fabricate and install the tensile fabric component of this project.
Design collaboration was undertaken using a controlling architectural geometry developed by Cox, which provided the centerline geometry for structural engineer, Arup. As the overall design evolved, the centerline model would be fed into the shop detailers software to update the fabrication drawings as well as provide the new geometry for our engineers.
Wind tunnel testing on the final form resulted in increased wind loads over the initial code studies, resulting in specific treatments on the edge extrusion to steel connections. Ponding concerns on the low slope roof were addressed by attention to detail – a relatively high pre-stress, use of top entry extrusion to help prevent initiation, setting the membrane level appropriately above steel bracing members and judicious variations to the slope of the roof at flat spots.
Construction requirements were considered right from the design stage with consultation between the project management, design and construction teams.
The installation method was developed to allow for weather, access limitations and OH&S requirements. Design meetings were held weekly with Watpac, Cox Rayner and ARUP to develop the membrane connections as well as the interface details with the perimeter steel claddings. These regular meetings also helped identify critical design items at every stage of the project, which in-turn allowed for a fast and efficient construction schedule (some design items were still being resolved as their construction elements were taking place).
The large steel superstructure is clad on the walls and roof with a combination of opaque and translucent Tensioned Membrane Fabric, each offering different light transmission levels
Developed in conjunction with the fabric manufacturer two custom PTFE membranes were used, FGT 800-Blockout and FGT 800 – LT-8 which offers 8% translucency (compared to the standard 12%). The LT-8 fabric was installed over the track (oculus area ) to enable delivery of natural lighting to the track for cyclists and events.
In total the project required the installation of 23 roof panels and 20 wall panels.
All of the walls half of the roof panels were produced in our state-of-the-art fabrication facility in Japan. The other half of the roof panels were made in our production facility here in Brisbane. The PTFE membrane was cut to size on our custom-built 20m membrane plotting table. The membrane panels were then fused together to form the shape of the roof using PTFE welding equipment. Membrane fabrication requires a high level of precision to ensure that the final product achieves its design parameters of shape and tension.
As the design relies upon regular fixing to the steel superstructure, it was necessary to develop a cost-effective method for mid span fixing without any membrane penetrations. Therefore, both the roof and walls use a tee section detail that can be readily prepared in the factory and installed cost effectively. Perimeter fixings had limited site adjustment, requiring significant analysis of the compensation data to achieve final design prestress.
Considered one of the highlights of the 2018 Commonwealth games, the stunning Anna Mears Velodrome is an example of the way tensile membranes can be used to create unique and iconic, world-class stadiums.