Entirely new engineering challenges arise when buildings are designed using materials other than concrete. The solutions to these challenges will not just help reduce the volume of concrete used, but will also make buildings more modular.
When designing a school building ten years ago, there would have been little to no discussion around the material from which the building was to be constructed, according to Engineers Australia Fellow Paul Easingwood FIEAust, Director, Structures and Facades at Bligh Tanner.
“We’re doing a number of school projects in New South Wales which are modular. It’s a mandate from Schools Infrastructure NSW. A lot of those systems are using timber, timber framing or cross-laminated timber.”
Just as timber in its various forms is becoming a more frequent selection, so is steel framing, particularly for the potential modularity such materials can offer.
But engineering challenges arise with new materials around construction methodologies, tolerances, procurement, accuracy and more.
“With long delivery times for some materials, it requires a different mindset to fix a lot of the design elements early and make sure everyone understands they cannot change those elements,” Easingwood said.
“Then there are new problems to solve. How does this timber work? How does it shrink? How do we connect it? How do we build earthquake design into it?
“There is a lot of new detailing to understand in the construction methodology, tolerance-wise, particularly for timber. You’ve got to develop that element of the building to within a mm. Meanwhile, you probably haven’t started building foundations on the site, because the materials have a very long lead time.”
There are also numerous detailing interfaces, he said. For example, how does the glazed facade interface with the timber frame? And what are the differential movements between the two, versus a concrete frame?
As a business, Easingwood said, Bligh Tanner is relatively boutique and niche. The fact that its senior people are very hands-on and enjoy such detail means they’re capable of going through the required exercise to solve such problems.
“That’s what engineers like to do – we like to solve problems,” he said. “This is a whole new problem to solve.”
A question of supply and demand
Before other products become a realistic concrete replacement on a larger scale, Easingwood said, supply chain has to catch up to demand.
“There are a lot of builders going under because they can’t get cash through the business, because they can’t deliver the end product with a sufficient level of efficiency,” he said.
“Once the supply side catches up and there’s a sustainable way of keeping that raw material coming through, we’ll be able to answer demand questions that are pushing some builders over the edge at the moment.
“Finally, as the profession is considering new technologies and new materials, we also have to think of the legislative side and make sure everything is fit for purpose. We have to do our due diligence, otherwise we end up with something like the combustible cladding failures. We can’t run too far ahead of the curve. People’s lives are quite literally at stake with everything we do.”
New reinforcement materials
While different and new materials are always a welcome addition, it’s important that we never lose our focus on the improvement of concrete and reinforcement, according to Clare Tubolets, CEO of the SmartCrete Cooperative Research Centre, which exists to enhance industry and research collaboration to decarbonise concrete.
“Concrete is always going to play a vital role in the built environment, so we need to consider more sustainable ways of using it,” she said.
“Research in engineered solutions is considering new generations of reinforcement to help reduce or remove the steel component and move to carbon or plastic fibres. At the same time we’re looking at recycling other industrial waste products into concrete as aggregate, including crushed glass, crumbed rubber and recycled concrete.”
While the more willing acceptance of change in engineering and construction is a positive, what’s required now is cross-sectoral collaboration.
“If you’re going to certify a building for 50 years, we’ll need to work together to gather a lot of data on the products that are used in that building,” Tubolets said.
“We are risk-averse in this sector for very good reason. But we’re moving in an excellent direction toward the future of concrete.”