Computer fire modelling is an important high-tech tool in fire safety engineering and fire science. The movement towards objective-based building codes means that these models will find application in performance-based fire-safety design of wood structures. Accordingly for more than a decade, fire researchers at Forintek strove to develop heat-transfer models for wood-frame assemblies exposed to fire. Then, in 2001 Forintek elected to outsource all future development of these models. This project provides funding, direction and oversight for the outside development of these design tools.
Canadian officials identified construction of wood-frame buildings in Japan as an important market priority. To aid them in their endeavours, in 2002-2003 Forintek contracted the development of a heat transfer model for exterior walls constructed with exterior expanded polystyrene-foam (EPS) insulation and ceramic-siding rains screens when subjected to standard fire exposures on the outside face. In 2003-2004 Forintek contracted to have further refinements made to that heat transfer model so that users would have the option of selecting either exterior EPS insulation or exterior semi-rigid glass-fibre insulation panels. That work was completed and comparisons between the model’s predictions and the results of full-scale tests show good agreement.
A paper describing Forintek’s heat transfer model for exterior walls with exterior insulation and non-combustible rain-screens, and comparisons between the model’s predicted outcomes and the results of full-scale fire tests on such assemblies will be presented later this year at the 8th World Conference on Timber Engineering.
In recent years Japanese building regulations were revised to permit construction of wood-frame (combustible) buildings within the high-density urban centres (Fire Protection Zones) of their larger cities if the major loadbearing elements in those buildings met specific requirements for fireproof construction. Those requirements have been dubbed the “one-plus-three” test requirements because for “low-rise” wood-frame apartment buildings and large houses they include exhibiting one-hour of fire-resistance when tested in accordance with ISO 834, and continued fire resistance without structural collapse when the test assembly is maintained under structural load with the fire-test furnace in-place against the side of the assembly for an additional three hours. Again, to assist in promoting markets for Canadian wood products in Japan, in 2003-2004 Forintek commenced modifying its WALL2D heat transfer model so that it would be capable of predicting the thermal response of walls subjected to the fire (thermal) exposures specified in Japan’s one-plus-three test method, parametric, and “real” fire scenarios. In preparation for that work, a Forintek scientist traveled to Japan to gather more information about the “one-plus-three” testing procedures. Later, Forintek contracted the service of Dr H. Takeda to travel to Japan to obtain thermo-physical property data for the gypsum board products commonly used in construction of wood buildings complying with Japanese specifications for fireproof construction. The information obtained from these two trips indicated that the successful completion of revisions to the WALL2D model would be much more difficult and require much more time than had originally been anticipated.
With the support of Forintek, one of the students enrolled at Carleton University, Steven Craft, chose as the topic for his PhD thesis the reliability of wood-frame floors in fire. One of the tasks that he is carrying out for his thesis is the development of a heat transfer model for floor assemblies constructed with solid-wood joists. Dr Hadjisophocleous, the Chair in Fire Safety Engineering at the university, and Craft’s thesis advisor, submitted a proposal to Materials Manufacturing Ontario (MMO) which would leverage Forintek’s financial support to Craft and enable Hadjisophocleous to build an entire research program around Craft’s thesis research. MMO accepted the proposal.
One of the biggest problems encountered in performance-base fire-safety design of large commercial structures is selecting the proper design or “realistic” fire scenario to be used when modeling fire resistance. For large commercial building with atria, establishing the required fire exposures on the boundaries of the atria from a fire within those tall, large open spaces is a particularly difficult issue. Therefore, in 2003, fire researchers in Australia submitted a proposal to the Australian Research Council (ARC) to study this subject. Forintek will provide some support for the work.
All of these activities will continue in 2004-2005.