22 February 2008
http://www.bluescopesteel.com.au/go/case-study/mobile-roll-forming-makes-for-a-fast-hundred-metres
This case study is about steel products that are proven to be economical, sustainable and perfect for this particular design and construction of the Grand Stand in New South Wales. This case study informs us about the best steel product to use for roofs with extremely large spans. In this case, roll forming appears to be the best option in terms of workability, as it reduces the amount of cranes and machinery used to construct the roof of the Grand Stand.
Location:
Blacktown, New South Wales
Country:
Australia
Project Size:
100 seat grandstand roof
Architect:
Ryder DesignInc
Builder:
Hooker Cockram
Contractor:
Axis Metal Roofing
Products Used:
LYSAGHT KLIP-LOK 700 HI-STRENGTH
Sheets of roofing more than 100 metres long have helped to create an iconic new grandstand building for the athletics track at Blacktown Olympic Park in Sydney's west.
Design and construction of the gull wing shaped roof has challenged and reunited the members of the Ryder DesignInc team responsible for the creation of the award winning Dunc Gray Velodrome.
The velodrome, which was the track cycling venue for the Sydney 2000 Olympics, was designed by Paul Ryder, an architect renowned for his elegant and simple structures, and implemented with DesignInc.
The new athletics venue grandstand at Blacktown, one of Ryder's last designs before his unexpected death early this year, has challenged the skill of those charged with its completion.
Design and construction of the 1200 seat grandstand has brought together architects DesignInc, builders Hooker Cockram, roofing contractor Axis Metal Roofing and building products supplier, BlueScope Lysaght.
Axis Metal Roofing, and BlueScope Lysaght collaborated on the visually stunning but technically challenging construction of the Dunc Gray Velodrome roof, which involved the world first use of curved LYSAGHT® Cee purlins supporting specially tapered LYSAGHT LONGLINE 305® cladding.
The Blacktown Olympic Park grandstand roof is a smaller structure, but its construction also required careful planning and innovative solutions.
"There were several challenges from the outset," Axis Metal Roofing Director, Hugh Tabone said. "A roof designed as a massive valley gutter looked spectacular, but we had to consult BlueScope Lysaght about the practicalities of actually erecting it.
"We sat down with Mike Celeban, BlueScope Lysaght's New South Wales Technical Support Manager, and eventually we got to the stage where we fabricated a prototype of the critical elements to replicate the pitch and fall of the roof.
"We were using LYSAGHT KLIP-LOK 700 HI-STRENGTH® cladding, which is a concealed fix profile and we built the prototype to put it to some quite unusual tests."
The Ryder DesignInc design for the grandstand envisaged rainwater cascading over the ribs of the roof sheeting at right angles to its rain shedding design, then coursing along the low point of the cladding to spill into a cauldronstyle tank at one end of the structure for recycling.
"The BlueScope Lysaght guys are really good," Hugh said. "They worked with us on the most effective method for sealing the laps and eventually we got to the stage where we conducted a flood test to see whether the roof would leak during heavy rain.
"It was the crucial part of the project, so we had representatives from DesignInc and from Blacktown City Council on hand as well as from BlueScope Lysaght.
"We filled the prototype section with water and there wasn't a drop of leakage. In fact, months later the test rig still has water in it and it still hasn't leaked."
With the issue of watertightness resolved there was still a major construction hurdle to be overcome before the design could be declared a success.
"There was only one way we were ever going to get 103 metre sheets of cladding up onto the roof," Hugh said.
"On-site roll forming was the answer, but the roll forming mill also had to have the capability to output sheets directly to the roof frame, so that we could avoid having to use multiple cranes to lift them into position."
Axis Metal Roofing discussed the challenge with BlueScope Lysaght's mobile roll forming Project Manager, Bill Reeve, who pointed out that the machine has a theoretical sheet length limit of up to 320 metres.
Getting the sheets of LYSAGHT KLIP-LOK 700 HI-STRENGTH® cladding onto the roof wasn't a problem either, since the mobile mill is fitted with a tilt mechanism which allows it to output to eaves or roof edges up to 13 metres high.
BlueScope Lysaght conducted a site inspection to confirm the suitability of the roll forming solution and worked with Axis Metal Roofing to resolve issues related to fixing the sheets to the framework.
"This wasn't a particularly large job for us, but the challenge created a lot of interest," Hugh Tabone said.
"It only required seven long sheets of LYSAGHT KLIP-LOK 700 HI-STRENGTH® cladding for the central section of the gull wing shape, but the mobile roll former also produced the various shorter lengths required.
"We had great co-operation from BlueScope Lysaght's crew and that made a challenging job easier than it could have been.
"One of the unusual requirements brought on by the design was that our roofers had to apply sealant to the side laps of each 103 metre sheet. The sealant loses its workability after 20 minutes, so smooth production of each sheet was essential.
"The BlueScope Lysaght roll former crew produced each sheet as we needed it, then waited for us to apply the sealant and fix the sheet to its concealed clips before they rolled the next one."
BlueScope Lysaght's mobile roll former is built on a structural cage to eliminate roller distortion and the need for time intensive adjustments, which on conventional roll formers can become more frequent as sheet length increases.
For long length sheets rolled at ground level a spreader bar is available to minimise sheet flexing problems while craning cladding to the roof frame.
The spreader bar can be extended in 12 metre steps to a maximum span of 72 metres.
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