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

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

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 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 2 Structural 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 3 Thermal actions for temperature analysis Thermal actions are given by the net heat flux: Both the convective and radiative flux taken into consideration

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

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

10 Section 3 Thermal actions for temperature analysis The configuration factor should be taken as 1.0 unless prEN 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 3 Nominal temperature-time curves Standard temp-time curve Temp (deg C) Time (mins)

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

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

14 Additional points for 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 3 Natural fire models - Annexes methodology Annex B Annex A Annex C Annex D Annex E Annex F Annex G Parametric temperature-time curves – method of determining compartment fire temperatures Method of calculating the heating conditions and thermal actions for external members exposed through façade Thermal actions of localised fires – heating conditions etc. 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 Equivalent time of fire exposure – method of determining equivalent time and then compared with design value of standard fire resistance Calculation of configuration factor including position and shadow effects

16 Section 4 Mechanical 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


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