One problem, three engineers, no constraints
“Tell me how to avoid wind and rain on a project — imagine taking the effects of wind and rain away from construction and what that would do to time. On our projects in Brisbane we have a 12.5% inclement weather contingency, and down on the Gold Coast it’s 15%. If you could drop a forcefield around the entire project so that wind and rain didn’t matter, you would have 12-15% time gains immediately. It’s Star Trek type stuff, but it would be worth billions.”
David Eden / regional director / Multiplex
Cranes, drones and giant fans
Bill Price / director / WSP
Losing time due to wind is often about not being able to use a crane. It seems to me there are two issues: the safety of the operator as the crane moves in the wind, and the load on the end of the crane swinging about.
So I started thinking about stopping the crane from moving. On our Goldman Sachs HQ site in London, there are four cranes. Could there be a way of linking them together to stabilize them in high winds? In other words, using the cranes as a kind of triangulated grid. Then you could install a net or platform, or a very lightweight membrane above the jib to provide some protection from the rain.
A beam crane is a similar idea. We always tend to think of cranes as tall masts with a jib that swings around. But to build a ship or a nuclear power station, you build a giant crane and run a beam across the top to lift things. You wouldn’t do it for a high-rise building, but it would work for a more modest out-of-town residential block or business park. Then you can do everything from a much more stable platform.
When we stabilize super-tall buildings, we use tuned mass dampers, so when they try to sway in the wind, there is a passive or active device — a weight or a tank of water — that counteracts the movement. Could we invent a tuned mass damper for the crane?
Taking a more active approach, you could use large jet fans to counteract the wind. With today’s technology, it would be possible to work out exactly where the crane should be, and then the fans and other devices could work together to keep the crane in the same spot. At the moment you might have to stop using the crane when the wind reaches 20-30m/s, but you could push that up to 40-45m/s by actively managing and counteracting the effects. Or you could over-specify the cranes — for example, using cranes that are designed for very windy places like Scotland or the North Sea. Of course, you would still need to manage the load. It might be much more efficient to use tethered drones to pull the load into the right spot. The crane would still take most of the weight, but drone technology could compensate for the swinging. A bucket of concrete might be a bit heavy, but it might work with a piece of cladding or something else with less mass. Cameras have something called “lens stabilization”, which senses the movement of your shaky hand and makes micro adjustments to counteract it. Could we not scale that up?
Rain is trickier. It would take a massive amount of energy to vaporize it — if you consider that lightning is really just droplets of rain rubbing against each other, you can see the energy involved. Warehouses use what’s called an “air curtain”, which can be so powerful that a bird can’t fly through it. If there was a piece of kit that couldn’t get wet, could we blow air over it very fast so that the rain couldn’t land? That would be very expensive, but you might only switch it on occasionally — it’s not raining all the time.
"Theoretically, it might be possible to charge up the rain particles electrically and then use a giant magnet to pull them out of the way"
Theoretically, it might be possible to charge up the rain particles electrically and then use a giant magnet to pull them out of the way. But the infrastructure to do that might cost more than the building itself. And then there’s the effect on all the metal and electrical objects in the vicinity. Credit cards would cease to work, the bricklayers’ trowels would be sucked onto the magnet, and their lighters would all fly through the air …
Inflatables and umbrellas
Sol Lorenzo / technical director / WSP
Wind and rain? That’s a joke here in Canada. We build through six months of winter. The challenges of temperature and of snow are tremendous. We have to do all sorts of things, from preheating metal so that we can weld it, to putting special mixtures in concrete so that it will set in cold weather, to putting temporary enclosures around our buildings and heating them so that we can pour the concrete.
We tend to use temporary enclosures on a small scale around specific pieces of work, but in the far north when we’re building in permafrost, they can be pretty large. We essentially put up tents over smaller job sites.
I wouldn’t use a tensioned membrane for a temporary enclosure, but you could use a large inflatable air dome. The problem with inflatable domes is that they want to fly away as the air pressure lifts them off the ground, so the anchorages can be quite substantial. But this doesn’t happen with pneumatic domes, which are like a closed balloon or an air-tight bouncy castle. If you had an air-supported pneumatic dome, you could move it from one storey to the next. I think they could be scaled up without too much difficulty — there are some that are huge, almost stadium size, for soccer fields for example.
Recently we were involved in the preliminary concept for a Montreal-based start-up called “Upbrella”. You build the first storey of your building — but it’s not the actual first floor, it’s the roof. Then you start pushing that up and installing the rest of the building underneath.
"You build the first storey — but it’s not the actual first floor, it’s the roof. Then you start pushing that up and installing the rest of the building underneath"
You’re creating a moving envelope, so that the floor that you’re working on is completely protected from the elements at all times.
The effect of the weather is not totally eliminated because you still have to deliver materials to the site, but for the construction of the structure, this takes the weather out of the equation almost completely. It also optimizes the work of different trades, because you install all of your mechanical and electrical and plumbing systems on the floor below the roof, and then you push it up, so your workmen are always working at a convenient height, instead of on lifts.
We looked at the structural concept in terms of how it can resist lateral loads, its stability while it’s being lifted, what kind of forces are required to lift it, what kind of beams are required for those forces. As you have a one-storey wall essentially hanging off the structure of the roof, it does have to be built quite strongly in order to hold itself together as it moves. The system does come with a lot of constraints that you have to integrate into your design and it doesn’t allow you complete flexibility in your construction. So, I wouldn’t say that it’s the ideal solution, but it is definitely a good solution.
Bones, cells and spiders’ webs
Audrey McIver / technical director / WSP
I started off thinking about putting a massive tent over the site, the size of the Eden Project. Then, I thought: you know what, I’m thinking too small. One of the reasons that construction sites are vulnerable to the weather is because they are in a temporary condition. Buildings are fine in their permanent condition. That made me think about what we could do to make buildings that are strong in their temporary condition, without having to over-design them.
"The problem with steel or concrete structures is that they are inorganic. But what if we could merge that material with something organic, something that could grow itself?"
Recently I went to a lecture about how the inorganic structures of a building relate to organic structures. For example, the structure of the human body — our skeleton — is always in a temporary state, yet it can support the weight of our body and adjust to suit the things that we do. The problem with steel or concrete structures is that they are inorganic. But what if we could merge that material with something organic, something that could grow itself?
What if, in the future, it could be made of cells that reproduce or some kind of hybrid between organic and inorganic? We could manipulate the cells or programme them in such a way that they grow into the building, and then when they reach a certain point, that’s it, it gets switched off. The weather wouldn’t matter because the building would always be strong — in the same way as the human body can lose weight, gain weight, start running marathons, stop running marathons, and adjust.
Think about all the innovations that are happening in the organic field. If we can grow bone, could we somehow replicate that so that buildings 3D-print themselves? Or think about how crystals form — could a building replicate like that? Or spiders’ webs, which are as strong as steel. Why can’t we build bridges the way that spiders spin webs? Why are we still working with materials that have been there for 200 years?