Minimalism and elegance were the goals of the engineers responsible for taking World War II–era infrastructure and transforming it into a 21st-century exhibition space.
At Sydney’s Domain, in a cavern deep beneath the ground, great gnarled masses loom out of the black, illuminated by slowly shifting spotlights before winking back into the void.
The forms resist attempts at categorisation; from one angle they look like machinery, as if dinosaurs had been rebirthed as metal and mechanics. But from other angles, they seem eerily organic, like alien life had begun to metastasise in the gloom.
The setting is a disused fuel bunker: built in the 1940s to serve ships fighting in the Pacific Theatre of World War II, decommissioned 50 years later, and today home — at least temporarily — to the strange monuments that form Argentine-Peruvian artist Adrián Villar Rojas’s exhibit The End of Imagination.
Villar Rojas was the first artist commissioned to use the space known as the Tank gallery, a major new attraction in Sydney Modern, the $344 million expansion of the Art Gallery of New South Wales, which opened in December last year.
But before Villar Rojas had even seen the space with which he would fill his unsettling constructions, it was the project’s engineers who were tasked with descending into the darkness of the decommissioned fuel tank.
“We looked down into that space and it was all covered in water,” recalled Arup structural engineer Andrew Phillips. “We had to go down a temporary scaffold — the gallery had kindly erected scaffolds so we didn’t have to dangle down a rope — but we all had to wear gumboots because it was filled with water.”
Acoustic engineer Harvey Yang described the future gallery in otherworldly terms — “a feeling of magic”.
“It was very dark; it’s not like how at the moment you have lights or you know where the exit is,” he said. “When you first step on to the floor, the water starts making a sound and the tank itself echoes. It felt really amazing — this echo from history.”
Building on bridges
The tanks were first installed when, during the lead-up to World War II, the British navy requested that Australia build a dry dock on Garden Island to ready for potential conflict in the Pacific.
That required fuel tanks for ships arriving in the facility, and two were constructed by excavating massive pits in the hillside, which were enclosed with concrete gravity walls and finished with precast columns and a flat slab laid across the top.
Years later, the Art Gallery of NSW turned its attention to the space, looking to integrate it into an expansion that would double its floor space to 40,000 m2. Of the two tanks, the south one would become the Tank gallery, while the other would be used for back-of-house purposes, such as loading and storage.
Adding to the complexity was the Eastern Distributor, a highway running through a tunnel directly to the original gallery’s north — exactly where the Sydney Modern wing was to be built.
The entry to Sydney Modern would not be built on solid earth, but rather on a land bridge spanning 11 lanes of traffic.
“The art gallery wanted the new wing to be not too far away from the old wing; some of it had to be on top of that land bridge. It’s not every day that you build a building on top of a bridge, but that was the challenge,” Phillips said.
“We had to do some very detailed analysis of that land bridge structure. We analysed every part of it [and] we designed the structure to be as light as possible and then to spread its loads as widely as possible to minimise the impact on that land bridge.”
The engineers also had to consider potential seismic activity, and sought to minimise the horizontal loading the building would impose on the land bridge.
“We designed the new structure to be able to slide across the top surface of the land bridge, so that in an earthquake, they could move independently of each other,” Phillips said.
Historical analysis
Although Arup was able to draw on recent and relatively detailed information for its work with the land bridge, this wasn’t the case with the new gallery’s oil tanks.
“Because at the start, we didn’t have a lot of information about that 1940s structure; we didn’t have any drawings of it that we could use to analyse it, so we had to do a lot of the investigation ourselves,” Phillips said.
“We had no idea how strong it would be, how much capacity it would have to have with a new building built on top of it, and so we did a lot of investigation into it.
“There were geometric surveys done and then material testing on the concrete, scanning of the concrete to find what the reinforcement was inside the concrete, strength testing of the reinforcement through taking samples of it.”
They also tested for any damage the oil stored in the tank might have done to the concrete.
“There was that challenge of knowledge — or the lack of knowledge that we had — and how we overcame that,” Phillips said.
“And then the challenge of, once we did have information about it, working out where we could put the new structure over the top of it, and how we could spread the loads to minimise the impact on it.”
In working with the original materials, the team sought to retain the vast majority of the 125 columns within the tank.
“We analysed every single one, effectively. We did a load analysis of all the structures coming down on the top, plugging it into a model, to work out where all the forces were going to trickle down,” Phillips said.
“So we knew exactly what was going to happen in the future in terms of loads on each column, and then worked out that we could spread the new loads sufficiently to only have to replace 10 of the 125.”
Listening session
While the structural engineers dealt with the physical challenges, Yang fine-tuned visitors’ aural experience by drawing on his deep knowledge of the acoustic demands of gallery spaces.
People walk through these buildings in particular ways, and it is important to ensure the sounds of footfalls and quiet conversation don’t resonate unpleasantly throughout the vast rooms.
But the Tank gallery required a different approach to other projects Yang has overseen, such as Hong Kong’s M+ gallery or his subsequent work on the new Powerhouse Museum in the Sydney suburb of Parramatta.
For the Tank, Yang pursued what he described as a “do nothing” tactic.
“Traditionally, acoustic design is always about trying to control something — we control noise, we control reverberance to make it sound comfortable,” he explained.
“But this type of building is basically an empty space shell for the artworks to fill in. There’s no right or wrong [approach] to it.”
And for a gallery like Sydney Modern’s Tank, it was more important to retain the distinctive qualities of the space and the experiences it offers to visitors.
“The unique experience, as part of the history of that [space] and the origin of the building, should be kept,” Yang said.
“It’s understanding that space and communicating how to use the space and the limitations and consideration of what needs to be done [to exhibit there].”
To measure the properties of the Tank, Yang needed to gather data about how sounds behaved.
That meant recording a variety of sounds, including a French horn being played and a balloon being popped — all before construction even began on the gallery.
“We have this technique to record the signature of a room, which we call the impulse response of the space,” Yang said. “[We] generate an impulse signal in the room, and how it reflects that sound back into your microphone gives you a signature of the room’s acoustic characteristics corresponding to that point in space.”
Yang then created a digital representation of the space with that recording, which could be used for later analysis or to model changes.
The model created from that data could then be replayed in Arup’s SoundLab, helping the engineers further understand how sound interacts in the room. More than 90 recordings were used for the Tank gallery, allowing Arup to model five different operational situations for various acoustic treatment options.
The situations modelled were: a conversation in the space, a static exhibition, an event with more than 800 people, a formal speech and a musical performance.
This work showed that certain flexible and low-impact additions, such as acoustic curtains or baffles, might be necessary to hold certain events in the gallery.
Beautiful work
The minimalist approach was not restricted to the sound engineering. Arup Principal Andrew Johnson, the technical director on the project, said the engineers, the gallery and architectural firms Sanaa and Architectus agreed on the “do nothing” approach from the outset.
“Everyone saw it as a space that should be just left as it was, and so, from a functional point of view, it was all about the minimal amount of invasiveness or intervention to make it a space that could be used,” he said. “And that was from not just acoustics and structural, that was from a services point of view as well, and then from a curatorial perspective. How could we leave this space alone, and still curate it and use it?”
Phillips affirmed that the team sought to intervene as little as it could.
“The idea was to keep that structure as intact as possible and have as little impact as you could while making use of the space,” he said.
“We wanted to minimise the impact on heritage, minimise the structural work we had to do to make it work, and minimise servicing.”
But when intervention was necessary, the quality the team sought to accentuate in its contribution was — fittingly for an art gallery — beauty.
“For instance, there had to be a way of getting people into the tank, so Sanaa came up with this concept of the spiral stair that comes down through a hole in the roof,” Phillips explained.
“Which is obviously a very clear intervention, but the thinking being, well, if we have to intervene, let’s make it beautiful and elegant.
“And so we helped them design this stair that’s really a monolithic piece of steel that’s quite a beautiful structure in itself.”
This ability to focus on the aesthetic qualities of the project, the engineers said, was the result of strong collaboration with the architect and the gallery.
“Listening to the architects, listening to what’s important to them, and then trying to bring our skills to realise that vision,” Phillips explained.
For Arup, that meant understanding the level of complexity underlying Sanaa’s streamlined style. The team focused on getting the details right.
“There’s a lot of visible steel structure in the building, and where the pieces of steel connect to each other, there are dozens of different ways to design a connection between a steel beam and a steel column, and a lot of them are not very elegant,” Phillips said. “We could detail those connections to be as minimalist as possible and minimise the bolts and plates — more welding than bolting and plating and make those welds as minimalist as possible.”
The beauty extended to the engineering itself, Johnson said.
“We can make the building elegant from an engineering and architectural point of view by making it true in the way it performs,” he explained.
“The column grid is relatively modest, other than the large-span gallery, and that allows us to use an elegantly slender column diameter for its height.
“The roofs of the entry pavilion and what we call the café roof, which is that curved roof over the atrium space … have a two-way beam structure that is slightly unusual — but it’s very effective and efficient structurally on a square grid.”