BSI PD 7974-3:2019
$215.11
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)
| Published By | Publication Date | Number of Pages |
| BSI | 2019 | 128 |
This Published Document provides a framework for developing a rational methodology for design using a fire safety engineering approach through the application of scientific and engineering principles to the protection of people, property and the environment from fire. This Published Document considers the following issues:
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the conditions that lead to fire spread beyond the enclosure of fire origin (see also Annex A);
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the selection of design fires depending on the objectives of the assessment (see also Annex B);
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the thermal and mechanical response of the enclosure boundaries and its structure to the fire conditions (see also Annex C and Annex D);
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the impact of the anticipated thermal and mechanical responses on adjacent enclosures and spaces; and
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the structural responses of loadbearing elements and their effect on structural stability, load transfer and acceptable damage according to the design and purpose of the building (see also Annex E and Annex F).
Annex G provides a methodology for establishing the extended application of fire resistance test results.
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 6 | Foreword |
| 9 | 1 Scope 2 Normative references 3 Terms and definitions |
| 12 | 4 Symbols |
| 15 | 5 Design approach to PD 7974-3 5.1 General 5.2 Interaction with BS 7974 framework Figure 1 — Interaction between the various professions and the design team in addressing PD 7974-3 factors 5.3 Functional objectives |
| 16 | 5.4 Identification of fire hazards and possible consequences 5.5 Identification of acceptance criteria and appropriate methods of analysis |
| 17 | 5.6 Establishing trial fire safety designs 5.7 Establish fire scenarios for analysis |
| 18 | 5.8 Analysis Figure 2 — Procedure for analysis within PD 7974-3 |
| 19 | 6 Analysis methods 6.1 General 6.2 Basis of analysis |
| 20 | 6.3 Accuracy 6.4 Means |
| 21 | 6.5 Measures 7 Evaluation of fire conditions 7.1 Design fire characterization 7.2 Selection of design fires |
| 23 | Figure 3 — Gas temperature in non-combustible and combustible compartments [8] 8 Evaluation of thermal response 8.1 Thermal response of elements within enclosure 8.2 Empirical data |
| 24 | 8.3 Simplistic calculations |
| 25 | 8.4 Advanced calculations 8.5 Quantitative analysis of heat flow by conduction |
| 27 | 8.6 Quantitative analysis of heat flow by convection 8.7 Quantitative analysis of heat flow by radiation |
| 28 | 8.8 Characterizing the condition of fires spreading from openings in enclosures |
| 29 | 9 Behaviour of separating elements in fire 9.1 Behaviour of fire-resisting separating elements |
| 41 | 9.2 Maintaining the separating capability of elements or constructions |
| 43 | Figure 4 — Typical detail showing protection to a floor beam with a service penetration |
| 44 | 9.3 Behaviour of non-fire-resisting separating elements Table 1 — Notional period of fire endurance for which imperforate condition can be assumed for unproven elements subject to fire exposure |
| 45 | 10 Analysis of structural response of loadbearing structural elements and frames 10.1 Concepts |
| 46 | Table 2 — Partial safety factors for loads (PD 6688-1-2:2007, Table 1) |
| 47 | 10.2 Acceptance criteria |
| 48 | 10.3 Methods for determining structural response |
| 50 | Figure 5 — Maximum steel temperature concept Table 3 — Values of kb |
| 53 | Figure 6 — General approach to structural fire safety design |
| 57 | Annex A (informative) Fire spread mechanisms |
| 59 | Figure A.1 — Routes for fire transmission |
| 61 | Annex B (informative) Design fires |
| 62 | Annex C (informative) Heat transfer (and thermal response) of specific materials Table C.1 — Guidance on the material surface emissivity of construction materials |
| 63 | Figure C.1 — Configuration factors for typical scenarios |
| 68 | Figure C.2 — Calculation of section factors |
| 69 | Table C.2 — Calculation of element factors (EF) |
| 70 | Figure C.3 — Calculation of element factors |
| 71 | Table C.3 — Typical set of coating thicknesses for a profile non-reactive spray-applied protection system |
| 72 | Figure C.4 — Typical set of board thicknesses for a box encasement fire protection system |
| 75 | Figure C.5 — Compartment parameters Table C.4 — Location of columns between windows to avoid direct flame impingement |
| 76 | Figure C.6 — Spandrel beam with shielded flanges Table C.5 — Spandrel beams |
| 79 | Figure C.7 — Calculation methods for determining the temperature profiles though masonry elements |
| 80 | Figure C.8 — Temperature gradient through autoclaved concrete masonry with a density of 400 kg/m3 to 800 kg/m3 |
| 85 | Annex D (informative) Temperature-dependent properties of non-loadbearing construction systems — Thermal properties of materials used in composite sandwich panels Table D.1 — Comparison of expansion of materials used in composite sandwich panels |
| 86 | Table D.2 — Comparison of specific heat capacity of materials used in composite sandwich panels Table D.3 — Thermal conductivity for various densities of mineral (rock) wool at elevated temperatures |
| 87 | Figure D.1 — Thermal conductivity for various densities of mineral (rock) wool at elevated temperatures Table D.4 — Constants for calculating the thermal conductivity of mineral wool at elevated temperatures Table D.5 — Thermal conductivity of cellular glass |
| 88 | Table D.6 — Thermal conductivity of expanded polystyrene Table D.7 — Thermal conductivity of extruded polystyrene Table D.8 — Thermal conductivity of phenolic foam Table D.9 — Thermal conductivity of polyisocyanate foam Table D.10 — Thermal conductivity of rigid polyurethane foam |
| 89 | Table D.11 — Thermal conductivity through the cell gas for various blowing gases Table D.12 — Typical densities of core materials used in sandwich panels |
| 90 | Annex E (informative) Structural response of specific materials |
| 91 | Figure E.1 — Design methods for fire limit state (FLS) design adopted in BS EN 1992‑1‑2 |
| 93 | Figure E.2 — Principle design methodologies adopted in BS EN 1993‑1‑2 |
| 98 | Figure E.3 — Schematic representation of the compressive and tensile forces of a floor zone during fire |
| 99 | Figure E.4 — Illustration of the defection of a multi-zone composite floor system with protected and unprotected members |
| 100 | Figure E.5 — Illustration of catenary action developed in a multi–zone composite floor system |
| 103 | Table E.1 — Notional char depths for various species after 30 min and 60 min in the standard furnace test (BS 476‑20) |
| 104 | Table E.2 — Values of kfi for different components/elements |
| 105 | Figure E.6A — Definition of residual cross-section and effective cross-section |
| 106 | Figure E.6B — Relationship between k0 and time of fire exposure for unprotected surfaces, and for protected surfaces where tch ≤ 20 min Figure E.6C — Relationship between k0 and time of fire exposure for protected surfaces where tch >20 min Table E.3 — Determination of k0 |
| 107 | Figure E.7 — Equations (E.17) to (E.19) illustrated |
| 113 | Annex F (informative) Fire resistant load bearing structural solutions |
| 115 | Annex G (informative) Methodology for establishing the extended application of fire resistance test results |
| 122 | Bibliography |
