Probabilistic Risk Assessment of Life Safety for a Six-Storey Commercial Building with an Open Stair Interconnecting Four Storeys: A Case Study

Abstract

The gold standard for complying Performance Requirements is based on a Quantitative Probabilistic Risk Assessment (QPRA) 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 (CFD) 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 (BCA). The benchmark ERL was set as 1.36 deaths/1000 fires or a probability of death from a fire of 1.36 x 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 were recommended as the Alternative Solution. The trade-off analysis shows the sprinklers and wallwetting sprinklers in the office area resulted in a 20-fold difference in the building wide ERL, each. Schematic Design Fire Specification Event Tree Development Preliminary Risk Assessment and Scenario Generation Data Collection/Analysis Collect and analyse relevant data Determine credible fire scenarios (causes, locations, etc.) Conduct preliminary, qualitative risk analysis Complete risk ranking and short list design fire scenarios Identify all possible statuses of fire safety subsystems Construct event tree and generate possible outcomes Calculate probabilities using relevant data

Impact of Technical, Human, and Organizational Risks on Reliability of Fire Safety Systems in High-Rise Residential Buildings—Applications of an Integrated Probabilistic Risk Assessment Model

“…To implement PRA in buildings, Sabapathy et al [9] provide a systematic approach through a case study of a six-storey commercial building based on comparative expected risk-to-life (ERL) methodology. Weyenberge et al [10] developed an integrated quantitative risk assessment framework based on response surface modelling.…”

Sensitivity and Uncertainty Analyses of Human and Organizational Risks in Fire Safety Systems for High-Rise Residential Buildings with Probabilistic T-H-O-Risk Methodology

“…With the help of identified factors, risk computation is done in the next step using frequency and consequence analyses [27][28][29]40].…”

“…The overall risk for a system is given as the product of the frequency of occurrence of an accident scenario and its consequence. Risk models are based on the definition of risk as follows [40]:…”

Guest Editorial: Probabilistic Methods in Fire Safety Engineering

“…Finally, detailed applications are presented by Heidari et al [11] and Sabapathy et al [12]. The case study by Heidari et al focusses on the probabilistic assessment of simply-supported concrete slabs exposed to parametric fires and has informed the recent ISO/TR 24679-6:2017 [13], while Sabapathy et al present a comparative safety evaluation for a six-storey commercial building based on expected risk to life.…”