Tall timber buildings are on the agenda architects, engineers and fire services around the world. Every week brings a new proposal for a tall timber building – some remain as plans, while others get built.
A key question that continues to be asked is: what about fire? Timber structures, just like furniture, can be consumed by fire. If the fire burns for too long, the structure may be destroyed.
Any boy scout can tell you that it can be difficult to light a camp fire – and that if you pull a log from the fire, it will go out. Fire scientists have a term for this: self-extinguishment.
Over the last two years, researchers at the University of Queensland have been working closely with Hutchinson’s Builders and developer Happy Haus to understand the burning behaviour of exposed structural timber systems.
Last week University of Queensland researchers, in conjunction with Queensland Fire and Emergency Service, conducted a full scale fire test on a partially exposed Cross Laminated Timber Structure. The structure was designed by Aquatonic architects and Bligh Tanner engineers to represent the internal dimensions and finishes of a real apartment building. This project was funded by the Queensland Government Accelerated Partnership scheme (Constructing the Future of Housing), and was sponsored by Hutchinson’s Builders and Happy Haus.
The large scale test was led by investigators from the UQ Fire team; Ms Carmen Gorska, Ms Angela Solarte, Mr Aaron Bolanos, Ms Diana Casimiro, Mr Mateo Gutierrez and Mr Andrea Lucherini, and supported by Prof Jose Torero, Dr Angus Law, Ms Kathryn Humphreys and Dr Cristian Maluk. The research team carefully designed and positioned more than 250 sensors aimed at quantifying the fire intensity inside the compartment and the burning behavior of the exposed cross laminated timber. However, almost as quickly as the flames started, they stopped. Once the fuel in the compartment was consumed – the exposed timber walls rapidly stopped flaming. Over the course of the next five hours the temperature in the room was recorded as it returned to ambient conditions.
Self-extinguishment was achieved.
On completion of the test Professor Torero said:
“We know that self-extinguishment works in theory, but it’s great to see it in practice.”
Dr Law said that:
“This test was a huge success, and vindication for our industry partners. However, we must remember that small changes in the room configuration, timber thickness, fuel load, and construction detailing may give a different result. It is vital that new designs for timber buildings are robustly checked to ensure that they too, will self-extinguish.”
The research team at The University of Queensland is currently analysing the experimental data – and looks forward to generating detailed descriptions and analysis of the test that will inform the research and engineering communities about the outcomes of the research project, and its relevance in the fire safety design of future timber structures.