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That vision is based on a new system combining modular and skeleton construction, developed by Graz engineers and architects working with commercial partners.
“If a property is no longer fit for purpose, it is usually demolished, even though it would still be perfectly usable. Even in the event of damage to individual parts of the building, the entire building usually has to make way,” the researchers said.
This is because, in most cases, it is cheaper to build a new building than to carry out a conversion or renovation of the existing one, the team said – but such a waste of resources should be avoided whenever possible.
The construction and building sector consumes a huge portion of global resources, including up to half of raw materials, and is responsible for almost 40% of greenhouse gas emissions.
“That’s why the circular ‘R-strategies’ such as refurbishment, repair or reuse were very important for us in the Mohoho project, in order to develop a building system that offers a CO2-reduced alternative to conventional construction methods in high-rise construction,” said Christian Keuschnig from the Institute of Architectural Technology at TU Graz.
This was achieved with the modular skeleton system, the researchers said. In modular construction, prefabricated timber modules are stacked next to and on top of each other. Skeleton construction offers a supporting structure for flexible floorplans, which can be adapted by inserting or removing partition walls.
The team’s recyclable skeleton modules consist of cross-laminated timber floors and glulam (glued laminated timber) columns and beams. They can be connected using a node that enables load redistribution, meaning the failure of individual columns does not lead to the collapse of the entire building. “This firstly increases robustness and thus safety, and secondly enables the targeted repair of individual modules,” the team said.
To replace a module, the electricity, water and heating supply lines would first be disconnected. The node is designed so a lifting cylinder can be inserted between spacers, slightly lifting the support above and allowing the spacers to be removed. A shear plate would then redirect the forces after the lifting cylinder is lowered, relieving pressure on underlying components and creating space for the replacement process.
A building using the construction system could be up to 24 storeys high, the researchers said, although a concrete core would be needed above heights of six storeys, which would increase resource consumption and CO2 emissions.
“In Mohoho, we have combined the advantages of modular wood construction, such as the high degree of prefabrication and the short construction time, with the advantages of skeleton construction,” said Keuschnig.
“The prefabrication of the modules in a production hall under controlled conditions enables higher quality and traceability of the joints compared to on-site assembly, and ensures shorter construction times as well as reduced noise and dirt pollution.
“The repairability and flexibility of the construction system should significantly extend the operating life and lifespan of the building.
“During dismantling, the modules can either be reused directly or separated by type. We are already planning a follow-up project in which we want to test and scrutinise all of these things in practice.”
The team has submitted a patent application for the system. The project was funded by the Austrian Research Promotion Agency (FFG).
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