Australia 108: Double-pronged steel supply

Melbourne’s Australia 108 building will become the country’s tallest building by roof height when completed in 2020. Steel prestressing strand and structural steel have played their part in the construction of the country’s newest skyscraper.

The Australia 108 building in Melbourne’s Southbank precinct is a residential supertall skyscraper that will become Australia’s tallest building by roof height when complete, surpassing the nearby Eureka Tower.

InfraBuild (formerly LIBERTY OneSteel) has been instrumental in the supply of steel materials to the development, with more than 800 tonnes of steel prestressing strand used to construct the building’s 100+ levels, plus structural steel used to create a distinctive design feature that will be seen from all parts of Melbourne.

At 317m tall (25m taller than the Eureka Tower) and containing 1105 apartments, Australia 108 has been an exercise in defying the construction odds. 

Foundation works took approximately nine months to complete, with heavy machinery drilling down 46m to install the building’s 2m-thick core walls. Covering its distinctive facade are glass panels each weighing up to 300kg. 

“This country hasn’t seen a project like Australia 108 from a sheer numbers perspective,” said Graham Cottam, Multiplex Regional Managing Director. “If we look at the glass facade alone, all up some 2500 tonnes of glass spanning 47,000sqm will be used to create the tower’s innovative facade.” 

Prestressing strand: from iron ore mine to delivery

Post-tensioning specialists Postenco was engaged by builder Multiplex to perform post-tensioning of prestressing strand for each of the 100+ levels in this building. In total, Postenco will use in excess of 800 tonnes of 12.7mm and 15.2mm prestressing strand supplied by InfraBuild Wire (formerly LIBERTY OneSteel).

InfraBuild Wire’s Bruce Grady said both the 12.7mm and 15.2mm EHT strand used in this project was made at InfraBuild Steel’s Newcastle Wire Mill after having been mined at the company’s own mines.

“Through our vertical integration model, the iron ore mined in South Australia is sent to LIBERTY Steel and Mining’s Whyalla Steelworks for processing into the specific billet needed for strand feed wire. This billet is then transported to InfraBuild Steel’s Newcastle Rod Mill for further processing into a specific size of rod. That rod is then sent to the Wire Mill where it is drawn into wire spools that are then used through the strander in the manufacture of 7-wire PC strand.

“The 9.5, 12.7, 15.2 and 15.7mm prestressing strand manufactured by InfraBuild Wire complies with Australian Standard AS/NZS 4672 ‘Steel Prestressing Materials’ and is proudly Australian made,” he added.

Among the advantages InfraBuild Wire offered Postenco was competitive pricing, a fixed price offer for a period and volume, and an ability to quickly bring forward or delay deliveries in line with changes to the project construction timeline.

“The prestressing strand used needed to be made to a very strict standard in order for the design to be effective,” Bruce explained.

“Not only that but it was vital that the prestressing strand was delivered on time, week in week out, as any delay in the construction phase of the building was always going to be costly for Postenco.”

Structural steel design feature

Australia 108’s extreme height will ensure it becomes a Melbourne landmark once complete. But a distinctive feature of the building will set it apart from the nearby Eureka Tower and other buildings on the Melbourne skyline.

About two-thirds up the building will be a ‘ golden starburst’ design feature made of structural steel where pools, gymnasiums, theatrettes and an extensive terrace will be used by residents. Approximately 250 tonnes of steel have been used to create the structure, with the early stages of the feature now visibly jutting from the side of the building.

Ron Kandell, Managing Director of fabricator GFC Industries, said his company’s approach was to maximise off-site fabrication and minimise on-site installation.

“The starburst consisted of fabricated steel trusses which have been pre-cladded off-site and delivered to site as vertical modules,” Ron said. “Floor framing and roof framing were also fabricated into modules – and a transport height of up to 4.9m was required.

“This is one of the most technical challenging projects GFC Industries has taken on and I am proud to be part of this iconic project.”

InfraBuild Steel Centre’s (formerly LIBERTY OneSteel Metalcentre) Maurice Pessot worked closely with GFC Industries on the job and said: “We supplied hot-rolled structurals (universal beams and columns) to GFC Industries, plus a full value-add of cut, drill and notch on our processing beams through the InfraBuild Steel Centre branch at Scoresby. We also warehoused the product for GFC and supplied them to a timing schedule.”

He added that GFC specified the usual test certification on the steel supplied through InfraBuild Steel Centre, plus ACRS accreditation for the purposes of the Green Building Council of Australia’s (GBCA) Green Star rating scheme.

Australia 108 adds further weight to Melbourne’s claim to be the skyscraper capital of the country. The building’s first residents have already started to move into the building, which is expected to be fully completed in 2020.

 Images (except last) courtesy Multiplex