FIRE DTU BYG. Performance -Based Design Fully-Developed Fires DTU

Transkript

1 FIRE BYG Performance -Based Design Fully-Developed Fires

2 FIRE BYG Purpose To save lives and property Society: That the building can be accepted - Mainly Lives, but also - Major Losses - Cultural Heritage - Prestige. Client: Also Property and market share.

3 FIRE BYG Parametric fire Philip Thomas and Kunio Kawagoe at Mount Athos

4 FIRE BYG Parametric fire Opening Factor ρ 0 > ρ 1 h h V(x) x h ρ 1 O A h A tot

5 FIRE BYG Parametric fire Opening Factor ρ 0 > ρ 1 h h V(x) x h ρ 1 O A h A tot Bernoulli : (v(x)) g x ( 0 1) 2

6 FIRE BYG Parametric fire Opening Factor ρ 0 > ρ 1 h h V(x) x h ρ 1 O A h A tot Bernoulli : (v(x)) g x ( 0 1) 2 1 h ' 1 h ' 0 1 Av e ra ge velo city : vm v(x)dx 2g xdx h 0 h h / 2 2g (h ') C* h for h ' proportion a l to h. 0

7 FIRE BYG Parametric fire Opening factor H W w 1 h 1 w 2 L h 2 A 2(H L W L H W) tot A h w h i i i ave i wh i A 2 i O A h A tot ave

8 FIRE BYG Parametric fire Opening factor O O O O v v A A v A tot h h h O h, h h Atot h v 4h = Vertical distance from centre of gravity for vertical openings to the inside surface of the ceiling

9 FIRE BYG Parametric fire Thermal inertia (Danish: Berøringstallet) 2 ½ b c J / m s K 3 Desity kg / m c Heat capacity J / kgk Conductivity W / mk

10 FIRE BYG Parametric fire Fire course 345log (8 t 1) 10 T 20 C (t / t d) 2 (O / b) (0.04/1160) 2 3 td 7.80*10 q / O min =1.0 for a standard fire compartment = Time for end of the heating phase

11 FIRE BYG Parametric fire Large Flat Compartments Symmet ry Office plan

12 FIRE BYG h Parametric fire Large Flat Compartments ρ h ρ m Symmet ry m 22.8 m Office plan

13 FIRE BYG º C 1400 T d ( t) T h ( t) T 2 ( t) T 6 ( t) T 10 ( t) Parametric fire Influence of the cooling curve shape O = m ½ q = 179 MJ/m 2 b = Ws ½ /m 2 K t min

14 FIRE BYG Parametric fire course 345log (8 t 1) 10 T 20 C (t / t d ) ½ 2 O 0.02m, q 100MJ / m, t d 39 min kg / m, c 1000J / kgk, 0.80W / mk 2 ½ b 1166J / m s K, Hertz- Pettersson et.al. - T 2 ( t q O) T f ( t) T G ( t q O) t Wickströmt d ( q O) 78

15 FIRE BYG Parametric fire course 345log (8 t 1) 10 T 20 C (t / t d ) ½ 2 O 0.08m, q 150MJ / m, t d 14.6 min kg / m, c 1000J / kgk, 0.80W / mk 2 ½ b 1166J / Tm f ( t) slinterp K, A A 1 t 60 linterp A 0 A t d ( q O) Hertz- Pettersson et.al. - T 2 ( t q O) T f ( t) 600 Wickström- T G ( t q O) t

16 FIRE BYG Opening Factor Fire course Opening factor T max in slab with 30mm cover Reduction of concrete strength 150mm section Reduction of column strength 200x300 x4000mm m ½ ºC Hot Cold Hot Cold 200 MJ/m 2 0, MJ/m 2 0, MJ/m 2 0, MJ/m 2 0, MJ/m 2 0, minutes St. Fire (0,04) minutes St. Fire + cool (0,04) minutes St. Fire (0,04) minutes St. Fire + cool (0,04)

17 FIRE BYG Parametric fire x( O 200) x( O 100) x( O 400) O Maximum charring depth of structural pine wood for fire loads of 400, 200 and 100 MJ/m 2 as a function of the opening factor q x(o,q) (1.25 ) O O O

18 FIRE BYG Parametric fire For a steel structure protected by an intumescent paint of m 2 ºC/W and exposed by a fire with a fire load of 210 MJ/m 2 that the temperature will be largest for the opening factor 0.02 m ½ for ratios of fire exposed surface and volume up to 200 m -1 which means all HEB profiles Heavy HEA profiles until HEA 160 and Heavy IPE profiles until IPE 300 For more slender profiles the temperature will be largest for larger opening factors.

19 FIRE BYG Opening Factor for Industrial Housing with unknown customers Slow fires are usually more severe for structures than fast fires. A small opening factor is therefore on the safe side to apply. It is recommended to apply: 0.02 m ½ For all categories If the building is not known.

20 FIRE BYG Evacuation Criteria of importance for risk assessment for evacuation: Radiation, Visibility, Toxicology and Structural Stability.

21 FIRE BYG Dansk Byggeri, Erhvervs og Byggestyrelsen, COWI A/S, Betonelement-Foreningen, Rambøll A/S MT Højgaard A/S, Spæncom A/S Københavns Kommune Kristian Hertz Vejledning i dimensionering af bygningskonstruktioner for fuldt udviklet brand

22 FIRE BYG Integrity and insulation Examples Information T REI T R t R120+EI60 T EI t

23 FIRE BYG

24 FIRE BYG Fire Resistance Requirements: - R 120 min if 12 m up or -Parametric fire?

25 FIRE BYG Parametric Fires in Modern Danish Buildings Previously Windows 2 mm 6 kg Now: Windows 3 x 4 mm 50 kg O = 0.08 m ½ q = 200 MJ/ m 2 b = 1160 Ws ½ /m 2 C Temperature-Time Curvess min O = 0.02 m ½ q = 200 MJ/ m 2 b = Ws ½ /m 2 C

26 FIRE BYG Temperature profile in depth cm Temperature-Time Curvess min Strength Reduction of Prestressing Wires

27 FIRE BYG Fire Resistance Requirements: - R 120 min if 12 m up or -Parametric fire > R 120 min