APPLICATION OF PROJECT:
2 roof canopies for tennis courts – one to cover the synthetic show court and stadium seating; and one to cover another synthetic multipurpose court.
The project involved design, fabrication and installation of 2 fabric roof structures at the Marrara Tennis Centre (now Darwin International Tennis Centre) – one weatherproof shelter to cover the Main Show Court and its associated seating; and another protective shade shelter over a multi-purpose court. The project had a total plan covered area of over 3,750m2 with Mehler FR1000N being used on the Main Court and Gale Commercial Heavy 430 on the Multipurpose Court.
The main show court is a long spanning roof, covering a 60m x 50m space. Given the cyclonic location, this presented additional design challenges throughout the project.
DESIGN / FABRICATION / INSTALLATION BRIEF
The purpose of the project was to construct 2 structures that would ensure a good playing and viewing experience for competitors and spectators at a tennis center that would host future National and International events. The specification called for detailed attention to seam layout and preparation. The whole design had to take into consideration the cyclonic nature of the region. The structural design also had to consider lighting for both the court and stands.
The large lightweight structure required a detailed engineering analysis of the steel erection sequence to ensure that no parts of the structure were overloaded during the installation works. Several sequences were proposed and analyzed before we settled on the procedure that best suited the steel riggers and the requirements imposed by the site conditions. Temporary cable bracing was required to hold the main trusses in position until the permanent bracing steel was installed. The 43 metre main trusses were positioned using a coordinated dual crane lift. The trusses were held in place by the cranes until all of the temporary rigging was installed and the truss secured.
The very large fabric panels of the show court required careful management during deployment, due to the NT ‘wet season’. In March 2018, Cyclone Marcus hit Darwin halfway through the installation and the team had to stop work and prepare for the storm. The un-fixed fabric panels were secured to the steel in bundles and carefully wrapped with tarpaulins that successfully prevented any damage to the membrane.
The original design brief required the drainage system to have a minimum visual impact. As there are virtually only 4 locations available to support the downpipes, a conventional drainage system would have incorporated very large downpipes to accommodate the watershed from the 3740 m2 roof. The solution to this problem was to utilize a purpose designed syphonic system. The specialty syphonic heads reduced the downpipe sizes to a 160 diameter. Although originally specified as “drainage to the ground”, the syphonic discharge rate of 59 l/s quickly required a re-think of the ground level drainage works. The syphonic system was eventually plumbed into the in-ground hydraulic system.
Delivering a high column wide span roof in a cyclone zone was a significant loading demand on the supporting structure and creative design was involved to maintain a lightweight aesthetic in the primary steel while retaining the structural redundancy necessary to deal with the substantial wind load design cases.
The project required significant coordination with other contractors installing the surrounding structure, foundations, fencing, landscaping and the synthetic court surfaces.
The high design wind loads on the Show Court structure resulted in the footings being 1200mm diameter piers, 6 meters deep. After installing the footings, the Irish site foreman declared that the fabric will have blown away and be draped over Ayers Rock before these footings pull out!
Mehler FR1000N fabric selected for the Main Court structure chosen for its combination of strength for the cyclonic design conditions and ability to resist the harsh tropical climate.
Supporting steel with a 2 coat epoxy paint system per contract specification.
The Multi-Purpose Court structure used Gale’s Commercial Heavy 430 shade mesh. The supporting structure was however design for solid PVC loadings, should the client decide at a later date to upgrade to a waterproof membrane.
The materials chosen, suited the clients architectural intent and budget constraints.
COLLABORATION, CONSTRUCTION AND MAINTENANCE
MakMax worked closely with Halikos Construction to detail the structure and it’s supporting elements to achieve a standard of finish expected in a showcase facility. Architectural details were insufficient so much of the coordination of works was through Halikos’s collaboration with subcontractors. Halikos Construction was fantastic to work with as they took a proactive and cooperative approach to managing the design and installation works.
MakMax provided an Operation and Maintenance manual on the completion of works. This will form part of the overall maintenance requirement package that Halikos will supply the end client.
Entrant: MakMax Australia
Role played by Entrant: Fabricator, Installer
Location: Marrara, NT
Completed: April 2018
Client: Halikos Construction for Tennis NT
Architect: Mode Design Corporation, Darwin
Engineer: MakMax Australia