Eurocode 1: Actions on structures –

1. Eurocode 1: Actions on structures – Part 1–2: General actions – Actions on structures exposed to fire Part of the One Stop Shop program

2. Basic Outline • EN 1991-1-2 describes the thermal and mechanical actions for the structural design of buildings exposed to fire • Risk limitation • Individual • Society • Property • Environment

3. Specific Outline(Risk Limitation) • Load-bearing properties maintained • Fire and smoke generation limited • Fire spread limited • Safe occupant egress • Fire-fighter safety

4. Introduction • Common structural design rules provided • Consideration of fire scenario • Conventional (nominal) fires • “Natural” (parametric) fires • “National choice” annex • Alternative procedures • Allows parameters for in-depth analysis to vary from country to country

5. Section 1 - Scope • References • Assumptions • Fire protection must be maintained • Choice of fire design scenario must be by appropriate personnel • Terms and definitions • Nomenclature

6. Section 2Structural Fire Design Procedure • Selection of design fire scenarios • Determination of those design fires • Calculation of temperature evolution within structural members • Calculation of mechanical behaviour of the structure exposed to fire

7. Section 3Thermal actions for temperature analysis • Thermal actions are given by the net heat flux: Both the convective and radiative flux taken into consideration

8. Section 3Thermal actions for temperature analysis • The net convective heat flux component can be expanded as: Surface temperature of the member Coefficient of heat transfer by convection – values of which are discussed later Gas temperature in vicinity of fire exposed member

9. Section 3Thermal actions for temperature analysis • The net radiative heat flux component per unit surface area can be expanded as: Stephan Boltzmann constant Surface temperature of the member Configuration factor Emissivity of fire Effective radiation temperature of fire environment Surface emissivity of member

10. Section 3Thermal actions for temperature analysis • The configuration factor should be taken as 1.0 unless prEN 1992-1999 specifies otherwise. Alternative values may be calculated using Annex G. • For fully engulfed members may be approximated by • The values for the gas temperature may be taken from the nominal temp-time curves or the natural fire models, both expanded upon later

11. Section 3Nominal temperature-time curves • Standard temp-time curve Temp (deg C) Time (mins)

12. Section 3Nominal temperature-time curves • External fire temp-time curve Temp (deg C) Time (mins)

13. Section 3Nominal temperature-time curves • Hydrocarbon fire temp-time curve Temp (deg C) Time (mins)

14. Additional pointsfor simple analysis using nominal curves • The surface temperature results from the temperature analysis of the member according to Parts 1-2 of prEN 1992, 1996, 1999 as relevant • In case of fully engulfed members, the radiation temperature may be represented by the gas temperature around that member

15. Section 3Natural fire models - Annexes methodology Parametric temperature-time curves – method of determining compartment fire temperatures Annex A Method of calculating the heating conditions and thermal actions for external members exposed through façade Annex B Annex C Thermal actions of localised fires – heating conditions etc. Annex D Advanced fire models – one-zone, two-zone and field models Calculation of fire load densities and heat release rates based on building occupancy, size and type Annex E Equivalent time of fire exposure – method of determining equivalent time and then compared with design value of standard fire resistance Annex F Annex G Calculation of configuration factor including position and shadow effects

16. Section 4Mechanical actions for structural analysis • Imposed and constrained expansions and deformations • Caused by temperature changes due to fire • Result in effects of actions • Indirect actions • Constrained thermal expansion of members • Internal stresses due to thermal gradients • Thermal expansion of adjacent members • Other members outside compartment