Hybrid fire testing of the whole structure

Volume 16, Number 4, December 2011

Traditional fire resistance testing evaluates the performance of individual building elements with no consideration given to the interaction with other parts of the building. On rare occasions, fire performance is assessed by constructing and testing an entire building – a very expensive approach.

The NRC Institute for Research in Construction has developed and applied a hybrid testing technique to the fire performance assessment of buildings. It couples the analytical assessment of sub-assemblies with a physical test of part of the structure to simulate the response of the complete system.

Dr. Hossein Mostafaei stands in front of a column furnace. The furnace represents a fire compartment on the first floor of a six-storey building. The structural response to fire of the rest of the building is analyzed simultaneously on the computer.

Hybrid fire testing (HFT) was recently demonstrated for assessing the structural performance of a 6-storey reinforced concrete building. The scenario considered was a fire assumed to occur in a compartment on the first floor in the centre of the building. The column in the fire compartment was tested using the NRC’s column furnace facility while the structural response of the complete building was analyzed simultaneously using SAFIR, a specialized computer software for calculating temperature distributions in structures subjected to the fire.

During the column test in the furnace, the simulation software continually increases or decreases the column load based on the variation of the column deflections. The variation in the column deflections is continually used by the software to simulate the effect on the rest of the building.

HFT simulates the fire performance of the whole building at a lower cost than full-scale testing, and with more reliable results than prescriptive testing. In addition, various building structural configurations and properties can be evaluated at a lower cost by constructing only the structural elements that are physically tested in the furnace.

HFT offers the possibility of investigating various fire scenarios, using selected facilities for physical testing, and running the simulation analysis remotely at different locations anywhere in the world. Future studies will investigate applying the same hybrid methodology to other structural elements such as beams, floors and walls and to other types of structures such as bridges.

For more information

For more information or to become a project partner, contact Hossein Mostafaei at hossein.mostafaei@nrc-cnrc.gc.ca or 613-993-9729.