The gold standard for complying Performance Requirements is based on a Quantitative Probabilistic Risk Assessment method. This case study demonstrates the application of this approach to performance based design of a six-storey commercial building with an open stair interconnecting four storeys. Computational Fluid Dynamics based and zone fire as well as evacuation simulations are used to quantify consequences whilst detailed event trees underpinned by statistical data and analysis are utilised to calculate corresponding probabilities.
RESULTS are combined in a trade-off analysis tool which calculates the Expected Risk to Life (ERL) based on the trial design features included in each design option. The approach was used to determine a preferred design that achieves an acceptably low ERL and compliance with the Performance Requirements of the Building Code of Australia. The benchmark ERL was set as 1.36 deaths/1000 fires or a probability of death from a fire of 1.36 × 10−3 based on local statistical data. To obtain an optimum fire safety design (Alternative Solution) a layered approach was adopted in which fire safety systems were added until the risk to occupants in the building due to a fire is the same or less than the benchmark ERL. Eventually three sets of trial design were considered and in all cases the calculated ERL were roughly 22% lower than the benchmark. Eventually the trial design with the least number of fire safety systems was recommended as the Alternative Solution. The trade-off analysis shows the sprinklers and wall-wetting sprinklers in the office area resulted in a 20-fold difference in the building wide ERL, each.