Overview
ISO/TR 24679-8:2022 - "Fire safety engineering - Performance of structures in fire - Part 8: Example of a probabilistic assessment of a concrete building" - is a technical report that demonstrates how to apply probabilistic methods to structural fire performance. It revisits the concrete building case studied in ISO/TR 24679-6 and performs a focused probabilistic analysis of the most heavily loaded concrete column. The report addresses only the fire safety objectives related to structural performance and forms part of a broader building fire safety strategy.
Key topics
- Probabilistic assessment of structural fire performance: shows how to quantify failure probability and reliability index for a concrete column under fire exposure.
- Stepwise procedure aligned with ISO 24679-1: includes STEP 1–8 (scope, objectives, trial plan, design fire scenarios, thermal and mechanical response, probabilistic evaluation, assessment, documentation).
- Stochastic variables and uncertainty treatment: model uncertainties for loads and resistances, statistical parameters (mean, standard deviation, coefficient of variation).
- Example assessment types: full probabilistic (user-calculated), full probabilistic using listed fragility curves, and semi-probabilistic approaches.
- Use of standard fire exposure: analysis applies the ISO 834 standard fire curve as a clear baseline; references also to parametric (natural) fire approaches in ISO/TR 24679-6.
- Reference frameworks: ties to ISO 24679-1 (general method) and existing structural design guidance such as EN 1992‑1‑2 (Eurocode 2) where relevant.
Practical applications
- Fire safety engineers and structural engineers: to demonstrate compliance with fire safety objectives when deterministic guidance is insufficient or when a deeper understanding of failure probability is required.
- Risk analysts and researchers: to explore probabilistic modeling of fire-induced structural response and to develop fragility curves.
- Regulators, code developers and building owners: to justify alternative designs, assess post-fire performance, or support risk-informed decisions.
- Use cases:
- Verifying achievement of structural fire safety objectives for atypical designs.
- Quantifying reliability (probability of failure) for key structural elements.
- Enhancing stakeholder communication by making assumptions and uncertainties explicit.
Example case (from the report)
- Open-plan office building (approx. 420 m² floor area; total gross area 3 360 m²).
- Reinforced concrete frame: columns 500 × 500 mm, slabs 180 mm, concrete C30/37, steel Grade 500.
- Focused probabilistic evaluation of the most heavily loaded column under ISO 834 standard fire.
Related standards
- ISO 24679-1 - Fire safety engineering: general principles for performance of structures in fire.
- ISO/TR 24679-6 - Detailed structural fire analysis case study (parametric/natural fire exposure).
- ISO 834 - Standard fire curve (thermal action reference).
- EN 1992‑1‑2 (Eurocode 2) - Structural fire design guidance referenced in the example.
ISO/TR 24679-8:2022 is valuable when you need a worked example of probabilistic methods applied to structural fire performance, helping translate uncertainty into meaningful reliability metrics for design and decision-making.