Application of fire safety engineering principles to the design of buildings - Structural response to fire and fire spread beyond the enclosure of origin (Sub-system 3)
Overview
What is this published document about?
This is the third part in a series of published documents (PDs) in support of BS 7974 – a British Standard providing a framework for developing a rational methodology for designs that protect people, property and the environment from fire. The standard uses an alternative fire safety engineering approach, based on applying scientific and engineering principles.
The PDs contain guidance and information on how to undertake quantitative and detailed analysis of specific aspects of the design. They are a summary of the "state of the art" and are updated as new theories, calculation methods and data become available. They don’t preclude the use of appropriate methods and data from other sources.
Other parts in this series include:
Part 1: Initiation and development of fire within the enclosure of origin
Part 2: Spread of smoke and toxic gases within and beyond the enclosure of origin
Part 3: Structural response and fire spread beyond the enclosure of origin
Part 4: Detection of fire and activation of fire protection systems
Part 5: Fire service intervention
Part 6: Evacuation
Part 7: Probabilistic fire risk assessment
Who is this published document for?
Primary users will be fire safety engineering practitioners. Other users include:
Members of the fire and rescue service
Structural engineers
Architects
Government departments such as the Ministry of Defence
Universities (for teaching and research)
Regulators
Related industries such as insurers and systems engineers
Why should you use this published document?
It provides guidance on probabilistic risk analysis in support of BS 7974. It sets out the situations in which a probabilistic risk assessment can add value to traditional deterministic analyses and outlines acceptance criteria for the assessment. Furthermore, common analysis techniques of probabilistic risk assessment are summarily discussed.
It also includes data for probabilistic risk assessment, based on fire statistics, building characteristics and reliability of fire protection systems. It does not contain guidance on techniques for hazard identification or qualitative risk analysis. 
 What’s changed since the last update?
PD 7974-3:2019 considers the following issues:
The conditions within a fire enclosure and their potential to cause fire spread by way of recognized mechanisms and routes;
The thermal and mechanical responses of the enclosure boundaries and its structure to the fire conditions;
The impact of these anticipated thermal and mechanical responses on adjacent enclosures and spaces;
The structural responses of load-bearing elements and their effect on structural stability, load transfer and acceptable damage.