@article {bnh-5675, title = {Physics-Based Simulation of Heat Load on Structures for Improving Construction Standards for Bushfire Prone Areas}, journal = {Frontiers in Mechanical Engineering}, volume = {5}, year = {2019}, month = {06/2019}, abstract = {

Australian building standard AS 3959 provides mandatory requirements for the construction of buildings in bushfire prone areas in order to improve the resilience of the building to radiant heat, flame contact, burning embers, and a combination of these three bushfire attack forms. The construction requirements are standardized based on the bushfire attack level (BAL). BAL is based on empirical models which account for radiation heat load on structure. The prediction of the heat load on structure is a challenging task due to many influencing factors: weather conditions, moisture content, vegetation types, and fuel loads. Moreover, the fire characteristics change dramatically with wind velocity leading to buoyancy or wind dominated fires that have different dominant heat transfer processes driving the propagation of the fire. The AS 3959 standard is developed with respect to a quasi-steady state model for bushfire propagation assuming a long straight line fire. The fundamental assumptions of the standard are not always valid in a bushfire propagation. In this study, physics based large-eddy simulations were conducted to estimate the heat load on a model structure. The simulation results are compared to the AS 3959 model; there is agreement between the model and the simulation, however, due to computational restrictions the simulations were conducted in a much narrower domain. Further simulations were conducted where wind velocity, fuel load, and relative humidity are varied independently and the simulated radiant heat flux upon the structure was found to be significantly greater than predicted by the AS 3959 model. The effect of the mode of fire propagation, either buoyancy-driven or wind dominated fires, is also investigated. For buoyancy dominated fires the radiation heat load on the structure is enhanced compared to the wind dominated fires. Finally, the potential of using physics based simulation to evaluate individual designs is discussed.

}, keywords = {building standards, emissions, forest fire, physics-based simulation, wildland fire, wildfire, fire spread}, doi = { https://doi.org/10.3389/fmech.2019.00035}, url = {https://www.frontiersin.org/articles/10.3389/fmech.2019.00035/full}, author = {Nazmul Khan and Duncan Sutherland and Rahul Wadhwani and Khalid Moinuddin} } @conference {bnh-6406, title = {Simulations of radiation heat flux on a structure from a fire in an idealised shrubland }, booktitle = {Bushfire and Natural Hazards CRC Research Day AFAC19}, year = {2019}, month = {12/2019}, address = {Melbourne}, abstract = {

Wildland-urban interface areas are growing rapidly. Building standards are required to ensure that the structures built in fire prone areas are resilient to fire. Australian Standard AS 3959 was developed to prescribe construction requirements for houses in bushfire prone areas. The model in AS 3959 is applied to estimate the Bushfire Attack Level (BAL) that is expected on a structure during the nominally worst-case bushfire scenario that the house can experience. Once the BAL is based on the fuel and terrain near the structure, and determines the construction requirements for the structure. AS 3959 is based upon a view-factor model of radiant heat flux, which estimates the level of heat flux expected at the structure.

}, keywords = {building standards, Fire, heat flux, structure, Wildland-urban interface}, url = {https://knowledge.aidr.org.au/resources/australian-journal-of-emergency-management-monograph-series/}, author = {Khalid Moinuddin and Duncan Sutherland} }