High-tech construction wizard Adam Mitchell is responsible for making some of the most unique and striking structures in Australia possible, but his engineering journey began with humbler roots.
When you think about Sydney, what images spring to mind? The Opera House? The Harbour Bridge, maybe? In Melbourne, it might be Flinders Street Station or the MCG. Brisbane has the Story Bridge. Adelaide has its Festival Centre. And Perth? It’s not so easy to conjure up an image that epitomises the Western Australian capital.
Elizabeth Quay might come to fill that role, sitting as it does on the river with the city right behind. Its open space attracts tourists and provides a venue for New Year fireworks and other celebrations. Sitting right in the middle of the Quay is a 30 m high sculpture called Spanda by artist Christian De Vietri, which is fast becoming the backdrop of choice for visitors looking to get a snap that says Perth.
Adam Mitchell was the engineer in charge of turning De Vietri’s vision into reality. He describes it as the most exciting civil thing he’s done. And he’s been involved in a few.
Recent visitors to Melbourne could hardly miss the Barak Building on Swanston Street with its giant image of Wurundjeri elder William Barak gazing out across the city. Those same visitors might also have spotted the Orbis Building in South Melbourne with its golden composite façade and impossible curves. Both were Mitchell’s work.
“I’ve been involved in a few projects in my previous career, with Lamborghini and Porsche and high end beautiful things,” Mitchell said.
“Quite often in the civil realm you don’t get to deal with that. A lot of the time it’s sealed beams that are hidden away inside buildings. It’s a good mental challenge but to show someone, ‘This is what I worked on,’ it doesn’t really capture people’s imagination. Whereas you show them a picture of Spanda and they’re like, ‘Oh, wow. I’ve been past there’. It’s definitely a buzz.”
Realising a sculpture
According to Christian De Vietri, Spanda is a Sanskrit word meaning ‘divine vibration’ and the sculpture, which is six nested ellipses, is meant to evoke primordial energy such as ripples in a pond or the orbits of planets and galaxies. Mitchell was working for ShapeShift Design Technologies when De Vietri contacted them about turning his idea into physical form.
The Spanda artwork, located in Perth’s Elizabeth Quay, is the largest free-standing carbon fibre civil structure in the world. The largest ring is 30 m high, or about eight storeys.
“What Christian provided us was a Rhino format 3D CAD file, so he’d just done the skin of what you see there now,” Mitchell said.
“It’s quite a tapering shape. At the tip of the largest ellipse, the thickness is under 100 mm. You couldn’t deliver that in concrete because you wouldn’t even be able to get any reinforcing with the required coverage through there. It had to be something that was a hollow section. To do it out of steel, it would be all faceted. You couldn’t press it into that shape because you’d need a giant press to get something with the required wall thickness, and it’d be very difficult to get a nice smooth finish. So the logical thing is to deliver it in composite because you’re not limited by shape then.”
The mould was cut with a large computer numerical control (CNC) machine, measuring 40 m by 3 m by 9 m.
“They cut it out of polystyrene first and then put this hard tooling paste over it, which is like an epoxy-based resin,” he said.
“Then they cut that again, and make a hard tool. That CNC is within 0.1 mm of the 3D CAD in the tolerance that it delivers. You can pretty much cut any shape you want in those machines, with accuracy. Then it’s just a matter of dividing up the sculpture into something that you can fit in a container and reassemble.”
The largest ellipses were formed in 12 pieces, six tubular sections halved lengthways. The halves were bonded together in the factory, and when all the tubular sections were ready, they were transported to the site where the sections were connected together.
“There’s a sleeve connection there and some cover plates that went over the top to hide the connection, and then a little bit of onsite cosmetic work, just to make it look seamless,” he said.
Lifting the completed ellipses into place was the most stressful part of the whole job. Because of the design, there were no lugs to attach it to a crane so they had to be lifted with slings very carefully.
“We had a really big 13 m spreader bar and picked it up from the centroids of the two halves, so that it wasn’t under any load to spread or contract,” Mitchell said.
“We did a finite element analysis to work out the best spot to pick it up so it didn’t create any load in plane. Fortunately, the tubes were strong enough that we didn’t have to reinforce them. Because there were no lugs, we were using friction. So the load was actually spread out a fair bit over 500 mm worth of soft sling contact area.”
This was necessary to make sure they could get enough friction so the tubes wouldn’t slip and it also reduced the choking load on the tube. To avoid any twisting of the ellipses, people with dog lines held it straight once the crane picked it up.
It worked, but Mitchell said it was intense. To add to the complication, Perth’s notorious Fremantle Doctor wind started to blow before all the rings were erected, meaning the job had to be halted and finished the following day.
Building a name
Mitchell grew up on Phillip Island, southeast of Melbourne, and even though he works across the country, a number of his projects can be found in Melbourne. The Orbis apartment building in South Melbourne has a striking façade that appears to have been formed by giant spheres pressing into the building.
“Orbis was the first façade that I delivered in composite,” he said.
“The biggest challenge was when you CNC something it comes out millimetre perfect. But the slab that you’re mounting to might be plus or minus 10, 15, 20 millimetres. So we’ve got this highly engineered precision piece of façade and then we’ve got to try and match it up. When the whole façade’s connected like that and has continuous curvature, you can’t move a part up 20 mm because it has to remain tangent. You can see if it doesn’t have a nice smooth curve.”
The Orbis apartment building is seven storeys of convex curves and justting corners.
Another challenge was finding a resin that could meet stringent fire requirements.
“They’re not AS 1530.1 non-combustible but they are extremely hard to burn,” he said.
“Mechanically, they’re not as good as a standard epoxy, but you can still produce the cool shapes. You just need to use a bit more resin and fibre than you would if it was something flammable.”
He says the 2014 Lacrosse fire in Melbourne made people in the façade business look seriously at the flammability of their designs.
“It’s raised more and more questions about the suitability of materials for everyone in the façade business,” he said.
“Composites are never going to be as non-combustible as steel and concrete, but with the right people involved they can still be safely used on the building. The work we’ve completed has had all the relevant testing done to the relevant standards that the fire engineers have asked of the material and then they’ve designed their sprinkler systems and exits so that, as a system, it’s safe.”
He also finds it interesting to hear how people react to the designs of some of these structures and feels that both Spanda and Orbis are quite divisive.
“With Spanda, some people say it’s horrible, while others will be like, ‘Oh, it’s amazing, I love it. I really get how it’s representing the energy disappearing into the universe’,” he said.
“With Orbis, a lot of the locals down there don’t particularly like it but it’s won quite a few architectural accolades. I guess only time will tell but it’s definitely been fun engineering them and it’s provided me with a career after the decline of the advanced manufacturing in Australia, which I’m grateful for.”
Manufacturing blues
Mitchell’s career didn’t begin in structural engineering. Towards the end of school, he knew he had a passion for planes and computers but couldn’t decide which to do. Then he discovered the University of NSW offered a double degree in computer science and aerospace engineering.
“They didn’t offer it anywhere else so off I went,” he said of his decision to leave Phillip Island and head up to Sydney. The degree combination proved to be a winner as it landed him a job at GKN Aerospace in Melbourne, working on the Joint Strike Fighter Project doing structural stress analysis of the airframe.
The M-Pavilion in Melbourne’s Queen Victoria Gardens.
“I helped develop software to churn through all the data. I think there were 37,000 load cases for the Joint Strike Fighter,” he said.
“If you’ve got a part you’re trying to work out which critical locate do you use, doing it by hand, or Excel, is pretty hard work so we developed some software to look at the global finite element models.”
Interestingly, he says he had a little bit of exposure to finite element analysis while he was still at school.
Adam Mitchell in the lobby of the Orbis apartment building.
“My uncle was a mechanical engineer and had his own business doing oil and gas work so I’d sort of seen that side of things and thought it would be really cool if I could get involved in some of the software side of engineering,” he said.
The experience also gave him a good grounding in advanced materials.
“Most fighter jets still have an aluminium or titanium frame because of damageability,” he said.
“You can yield an aluminium frame and still fly home. You can’t overload a carbon fibre spar and make your way home. So yeah, there’s a lot of titanium in there and a lot of aluminium as well but all the exterior surface is carbon fibre.”
After four years at GKN, he realised the Australian aerospace industry was small and shrinking. To progress his career in aerospace, he either had to head overseas or look for another industry.
“At the time, Boeing had just closed all of its production up in Sydney and they were really the last big employer of aerospace engineers,” he said.
“I did a degree in something I loved but didn’t really think of the employment opportunities afterwards particularly well. That’s still an issue now. We’re graduating 5000 aerospace engineers a year, but if you see two graduate positions advertised a year, it’s a good year. There needs to be some sort of a warning for younger players there.”
He changed careers, moving into the automotive industry, first with EDAG and then Holden. His experience in finite element analysis and advanced materials came in handy.
The Barak Building. At the right distance, the lines form the shape of Indigenous leader William Barak’s face.
“I was involved in using large finite elements models to predict durability, fatigue cracking of the body and crash performance,” he said.
“As far as finite element analysis goes, it was the pinnacle: multi physics, highly non-linear transient events. It’s the sort of work that we don’t really do in Australia anymore. There’s still a little bit going on at Ford but most of it’s been taken away overseas and it’s a skill that we’ll never get back. It’s not code-based. You have to apply the physics and really have a deep understanding of the materials and the forces involved.”
However, it wasn’t long before the automotive industry became wobbly and the question of move overseas or change industries came up again.
“I did have the opportunity to go to Detroit or Shanghai but once you’ve seen those places and compared them to Australia, I could never take my family there. It just wasn’t an option with young kids so I tried to find a different approach,” he said.
“If you’re involved in making things, it’s been a pretty hard 10 years. So that’s why I tried to move across into construction and civil projects because you have to build them in Australia. There’s always going to be a demand for that locally. I’ve always really enjoyed composite materials since I was in university, so when that opportunity came up to work together with ShapeShift, I jumped at it.”
While Mitchell landed on his feet, he knows lots of people in the automotive industry who haven’t been so lucky.
“It’s heartbreaking really,” he said.
“I’m a fairly resilient person. I’ve managed to redefine my career but there’s a lot of guys I know who have gone from this really awesome job to assembling caravans or something and the wheels have really fallen off for them. It’s sad. I guess my message to anyone who wants to listen is that there’s a lot of really good engineers out there and if you give them a chance, they can change the path of their career and can be useful in other industries.”
The roller-coaster
Earlier this year, Mitchell decided to change gears once more, this time setting up his own consultancy based back on Phillip Island.
“The family’s still here and family’s important to me,” he said.
“I wanted the kids to know their grandparents and to grow up by the beach. It’s a rollercoaster. I won’t deny that, but it’s fun. I guess being your own boss is always good. We’re still pretty small at the moment. I’ve got two draughtsmen based in the cloud and myself but I’m hoping to grow the business to a team of five or 10 over the next five years or so. I’m making a living.”
