PART 1 THERMAL & MECHANICAL ACTIONS. DIF SEK Part 1: Thermal & Mechanical Actions 0/ 50

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1 DIF SEK PART 1 THERMAL & MECHANICAL ACTIONS DIF SEK Part 1: Thermal & Mechanical Actions 0/ 50

2 Background of the RFCS Project DIFISEK+ This project is funded by the European Commission in the frame of the Research Fund for Coal and Steel The aim of DIFISEK+ is to promote different projects of the last decades d that t dealt with fire engineering i and, which h results have been implemented in the EN This objective will be reached trough seminars held in different European countries. The partnership of the project is as follows: University of Hannover Institute for Steel Construction DIF SEK Part 1: Thermal & Mechanical Actions 1/ 50

3 Treated Topics Part 1: Thermal & Mechanical Actions Part 2: Thermal Response Part 3: Mechanical Response of Structures in Fire Part 4: Software for Fire Design Part 5a: Worked Examples Part 5b: Illustration of Completed Projects DIF SEK Part 1: Thermal & Mechanical Actions 2/ 50

4 Resistance to Fire - Chain of Events Θ Loads 1: Ignition Steel columns time 2: Thermal action 3: Mechanical actions R 4: Thermal response time 5: Mechanical response 6: Possible collapse DIF SEK Part 1: Thermal & Mechanical Actions 3/ 50

5 Thermal action on structure Composite Slab Column 1 side exposed 4 sides exposed DIF SEK Part 1: Thermal & Mechanical Actions 4/ 50

6 Heat transfer at surface of building elements h = + net, = h& h& net,c & + net r Net Radiative Heat Flux Net Convective Heat Flux Total net Heat Flux Exposed side Non-exposed side DIF SEK Part 1: Thermal & Mechanical Actions 5/ 50

7 Structural Fire Safety Engineering vs. Classification Prescriptive Performance based standard d fire natural fire classification fire safety eng. fire safety eng. fire safety eng. DIF SEK Part 1: Thermal & Mechanical Actions 6/ 50

8 Actions on Structures Exposed to Fire ČSN EN Prescriptive Rules Design Procedures Prescriptive Rules Performance-Based Code (Thermal Actions given by Nominal Fire) (Physically based Thermal Actions) DIF SEK Part 1: Thermal & Mechanical Actions 7/ 50

9 Nominal Temperature-Time Curve *) Nominal temperature-time curve Standard d temperature-, t External fire - & Hydrocarbon fire curve No data needed *) Simplified Fire Models Localised Fire Fully Engulfed Compartment - HESKESTADT - Parametric Fire Rate of heat release - HASEMI θ (t) uniform Fire surface θ (x, y, z, t) in the compartment t Boundary properties Opening area Ceiling height *) Advanced Fire Models + - Two-Zone Model - One-Zone Model - Combined Two-Zones and One-Zone fire -CFD Exact geometry DIF SEK Part 1: Thermal & Mechanical Actions 8/ 50

10 Prescriptive Fire Regulations Defining ISO Curve Requirements ISO-834 Curve (EN1364-1) θ [ C] T = log (8 t + 1) The ISO curve * Has to be considered in the WHOLE compartment, even if the compartment is huge ISO ISO ISO ISO ISO ISO ISO ISO * Never goes DOWN Time [min] * does not consider the PRE-FLASHOVER PHASE * Does not depend on FIRE LOAD and VENTILATION CONDITIONS DIF SEK Part 1: Thermal & Mechanical Actions 9/ 50

11 Stages of a Natural Fire and the Standard Fire Curve Temperature Pre- Flashover Post- Flashover C Flashover Natural fire curve ISO834 standard fire curve Ignition - Smouldering Heating Cooling. Time DIF SEK Part 1: Thermal & Mechanical Actions 10 / 50

12 Sprayed Protection DIF SEK Part 1: Thermal & Mechanical Actions 11 / 50

13 Partially Encased Beams & Columns DIF SEK Part 1: Thermal & Mechanical Actions 12 / 50

14 Actions on Structures Exposed to Fire ČSN EN Performance Based Code Design Procedures Prescriptive Rules (Thermal Actions given by Nominal Fire) Performance-Based Code (Physically based Thermal Actions) DIF SEK Part 1: Thermal & Mechanical Actions 13 / 50

15 Natural Fire Safety Concept 1200 θ [ C] Time [min] Implemented in: ČSN EN Some National Fire Regulations include now alternative requirements based on Natural Fire DIF SEK Part 1: Thermal & Mechanical Actions 14 / 50

16 NFSC Valorisation Project DIF SEK Part 1: Thermal & Mechanical Actions 15 / 50

17 Natural Fire Model *) Nominal temperature-time curve Standard d temperature-, t External fire - & Hydrocarbon fire curve No data needed *) Simplified Fire Models Localised Fire Fully Engulfed Compartment - HESKESTADT - Parametric Fire Rate of heat release - HASEMI θ (t) uniform Fire surface θ (x, y, z, t) in the compartment t Boundary properties Opening area Ceiling height *) Advanced Fire Models + - Two-Zone Model - One-Zone Model - Combined Two-Zones and One-Zone fire -CFD Exact geometry DIF SEK Part 1: Thermal & Mechanical Actions 16 / 50

18 List of needed Physical Parameters for Natural Fire Model Boundary properties Ceiling height Opening Area Fire surface Rate of heat release Geometry Fire DIF SEK Part 1: Thermal & Mechanical Actions 17 / 50

19 Characteristics of the Fire Compartment Fire resistant enclosures defining the fire compartment according to the national regulations Material properties of enclosures: c, ρ, λ Definition of Openings DIF SEK Part 1: Thermal & Mechanical Actions 18 / 50

20 Characteristic of the Fire for Different Buildings Occupancy Fire Growth RHR Fire Load q Rate f [kw/m²] 80% fractile [MJ/m²] Dwelling Medium Hospital (room) Medium Hotel (room) Medium Library Fast Office Medium School Medium Shopping Centre Fast Theatre (movie/cinema) Fast Transport (public space) Slow f,k DIF SEK Part 1: Thermal & Mechanical Actions 19 / 50

21 Fire Load Density Compartment Danger of Fire Activation floor area A f [m²] δ δ q1 1,10 1,50 1,90 2,00 Danger of Fire Activation δ q2 0,78 1,00 1,22 1, ,13 1,66 = δ ni Function δ of δ Active. Fire Safety δmeasures. m. f, d q1 q 2 ni q. Examples of Occupancies Art gallery, museum, swimming pool Residence, hotel, office Manufactory for machinery & engines Chemical laboratory, Painting workshop Manufactory of fireworks or paints Automatic Fire Suppression Automatic Fire Detection Manual Fire Suppression q f, k Automatic fire Automatic Automatic Independent Water Water Detection Alarm Extinguishing Supplies & Alarm Transmission System by by to Heat Smoke Fire Brigade δ n1 δ n2 δ n3 δ δ n4 n5 Work Fire Brigade Off Site Fire Brigade Safe Access Routes Fire Fighting Devices δ n6 δ n7 δ n8 δ n9 Smoke Exhaust System δ n10 0,61 0,87 or 0,73 0,87 1,0 0,87 0,7 0,61 or 0,78 0,9 or 1 1,5 1,0 1,5 1,0 1,5 DIF SEK Part 1: Thermal & Mechanical Actions 20 / 50

22 Rate of Heat Release Curve Stationary State and Decay Phase RHR [MW] 0 RHR [MW W] 5RHR [MW W] 70% (q f,d A fi ) 10 9 Steady Growing state phase A f x RHR f 10 Ultra- 8 Fast (FGR) 9 Fast COMPARTMENT FIRE (FGR) Medium (FGR) Fire AGrowth f x RHR Rate = FGR f 3 4 Ventilation Controlled Slow (FGR) Fire Decay phase 75'' 150'' 300'' 600'' Decay Phase t [min] t [min] t decay Time [min] DIF SEK Part 1: Thermal & Mechanical Actions 21 / 50

23 Natural Simplified Fire Model *) Nominal temperature-time curve Standard d temperature-, t External fire - & Hydrocarbon fire curve No data needed *) Simplified Fire Models Localised Fire Fully Engulfed Compartment - HESKESTADT - Parametric Fire Rate of heat release - HASEMI θ (t) uniform Fire surface θ (x, y, z, t) in the compartment t Boundary properties Opening area Ceiling height *) Advanced Fire Models + - Two-Zone Model - One-Zone Model - Combined Two-Zones and One-Zone fire -CFD Exact geometry DIF SEK Part 1: Thermal & Mechanical Actions 22 / 50

24 Simplified Fire Models Localised Fire LOCALISED FIRE θ (x, y, z, t) FULLY ENGULFED COMPARTMENT θ (t) uniform in the compartment DIF SEK Part 1: Thermal & Mechanical Actions 23 / 50

25 Localised fire test DIF SEK Part 1: Thermal & Mechanical Actions 24 / 50

26 Localised Fire: HESKESTAD Method Annex C of ČSN EN : Flame is not impacting the ceiling of a compartment t (L f <H) Fires in open air Flame axis Θ = + 2/3 (z-z -5/3 (z) 20 0,25 (0,8 Q c ) z 0 ) 900 C The flame length L f of a localised fire is given by : H L =-1,02 + 2/5 f D 0,0148 Q L f z D DIF SEK Part 1: Thermal & Mechanical Actions 25 / 50

27 Localised Fire: HASEMI Method Annex C of ČSN EN : Flame is impacting the ceiling (L f > H) concrete slab beam θg Y = Height of the free zone θ = Air Temperature at Beam Level Calculated by CaPaFi DIF SEK Part 1: Thermal & Mechanical Actions 26 / 50 x

28 Simplified Fire Models Fully Engulfed Compartment LOCALISED FIRE θ (x, y, z, t) FULLY ENGULFED COMPARTMENT θ (t) uniform in the compartment DIF SEK Part 1: Thermal & Mechanical Actions 27 / 50

29 Real Fire Test Simulating an Office Building Fully engulfed fire DIF SEK Part 1: Thermal & Mechanical Actions 28 / 50

30 Fully Engulfed Compartment Parametric Fire Temperature [ C] Annex A of ČSN EN Iso-Curve 1000 O = 0.04 m 900 O = 0.06 m 800 O = m 700 O = 0.14 m O = 0.20 m 600 For a given b, q fd, A t & A f time [min] DIF SEK Part 1: Thermal & Mechanical Actions 29 / 50

31 Natural Advanced Fire Model *) Nominal temperature-time curve Standard d temperature-, t External fire - & Hydrocarbon fire curve No data needed *) Simplified Fire Models Localised Fire Fully Engulfed Compartment - HESKESTADT - Parametric Fire Rate of heat release - HASEMI θ (t) uniform Fire surface θ (x, y, z, t) in the compartment t Boundary properties Opening area Ceiling height *) Advanced Fire Models + - Two-Zone Model - One-Zone Model - Combined Two-Zones and One-Zone fire -CFD Exact geometry DIF SEK Part 1: Thermal & Mechanical Actions 30 / 50

32 Advanced fire Models LOCALISED FIRE The Fire stays localised The Fire switch to a fully engulfed fire LOCALISED FIRE FULLY ENGULFED COMPARTMENT DIF SEK Part 1: Thermal & Mechanical Actions 31 / 50

33 Large Compartment Test Fire Load DIF SEK Part 1: Thermal & Mechanical Actions 32 / 50

34 Large Compartment Test External Flaming During the Test DIF SEK Part 1: Thermal & Mechanical Actions 33 / 50

35 Large Compartment Test After the Test DIF SEK Part 1: Thermal & Mechanical Actions 34 / 50

36 Two Zone Calculation Software OZone V2.2 DIF SEK Part 1: Thermal & Mechanical Actions 35 / 50

37 OZone results: Input and Computed RHR DIF SEK Part 1: Thermal & Mechanical Actions 36 / 50

38 OZone results: Gas Temperatures θ Hot θ Cold DIF SEK Part 1: Thermal & Mechanical Actions 37 / 50

39 OZone results: Smoke Layer Thickness DIF SEK Part 1: Thermal & Mechanical Actions 38 / 50

40 Calibration of Software OZone: Gas Temp MAXIMUM AIR T EMPERATURE OZone 1000 OZon ne [ C] MAXIMUM AIR T EMPERATURE IN THE COMPARTMENT TEST [ C] DIF SEK Part 1: Thermal & Mechanical Actions 39 / 50

41 Calibration of Software OZone: Steel Temp UNPROTECTED STEEL TEMPERATURE 1000 OZo one [ C] TEST [ C] DIF SEK Part 1: Thermal & Mechanical Actions 40 / 50

42 OZone: Case Study Gas te emperature e [ C] Influence of the Actives Fire Safety Measures q m δ δ f,d= q1 q2 δ i ni q f,k Office : A f = 291,2 m² O.F. = 0,04 m½ ; Fire Load No Fire Active Measures Off Site Fire Brigade q f,k = 511 MJ/m² Automatic Fire Detection & Alarm by Smoke Automatic Alarm Transmission to Fire Brigade Automatic Water Extinguishing System Design Fire Load q f,d [ MJ/m² ] Time [min] DIF SEK Part 1: Thermal & Mechanical Actions 41 / 50

43 Computer Fluid Dynamics: Software Sofie Grid definition DIF SEK Part 1: Thermal & Mechanical Actions 42 / 50

44 Sofie Results: Gas Temperatures DIF SEK Part 1: Thermal & Mechanical Actions 43 / 50

45 Resistance to Fire - Chain of Events Θ Loads 1: Ignition Steel columns time 2: Thermal action 3: Mechanical actions R 4: Thermal response time 5: Mechanical response 6: Possible collapse DIF SEK Part 1: Thermal & Mechanical Actions 44 / 50

46 Basis of Design and Actions on Structures S W G Q A C T I O N S Actions for temperature analysis Thermal Action FIRE Actions for structural analysis Mechanical Action Dead Load G Imposed Load Q Snow S Wind W Fire DIF SEK Part 1: Thermal & Mechanical Actions 45 / 50

47 Combination Rules for Mechanical Actions ČSN EN 1990: Basis of Structural Design Room temperature E γ G + γ Q + ψ γ d Q = G Q,1 1 0,i Qi Q,i i i >1 f.i. : Offices area with the imposed load Q, the leading variable action E d = 1,35 G + 1,5 Q + 0,6 1,5 W + 0,5 1,5 S DIF SEK Part 1: Thermal & Mechanical Actions 46 / 50

48 Combination Rules for Mechanical Actions ČSN EN 1990: Basis of Structural Design Fire conditions Accidental situation E fi,d = G + ψ 1or2,1 Q 1 + i >1 ψ 1or2,i Q i f.i. : Offices area with the imposed load Q, the leading variable action E fi,d = G + 0,5 Q Offices area with the wind W, the leading variable action E fi,d = G + 0,2 W + 0,3 Q DIF SEK Part 1: Thermal & Mechanical Actions 47 / 50

49 Values of ψ factors for buildings Action Imposed loads in buildings, category (see ČSN EN ) Category A : domestic, residential areas Category B : office areas Category C : congregation areas Category D :shopping areas Category E : storage areas Category F : traffic area vehicle weight 30kN Category G : traffic area, ψ 0 ψ ψ kn < vehicle weight 160kN 0,7 0,5 0,3 Category H : roofs Snow loads on buildings (see ČSN EN ) Finland, Iceland, Norway, Sweden 070 0, , ,20 Remainder of CEN Member States, for sites located at altitude 0,70 0,50 0,20 H > 1000 m a.s.l. Remainder of CEN Member States, for sites located at altitude 0,50 0,20 0 H 1000 m a.s.l. Wind loads on buildings (see ČSN EN ) 0,6 0,2 0 Temperature (non-fire) in buildings (see ČSN EN ) 0,6 0,5 0 DIF SEK Part 1: Thermal & Mechanical Actions 48 / 50 0,7 0,7 0,7 07 0,7 1,0 0,7 0,5 0,5 0,7 07 0,7 0,9 0,7 0,3 0,3 0,6 06 0,6 0,8 0,6 ( Reference : ČSN EN )

50 Load Factor η fi = γ G k + ψ fiqk, l GG k + γ Q, l Qk, l Load Fa actor E fi,d / R fi,d,t [-] Maximal Load level after R Massivity A m /V [1/m] DIF SEK Part 1: Thermal & Mechanical Actions 49 / 50

51 National Annex to ČSN EN Annex normative for buildings located in the Czech Republic Allows to change 10 parameters In 9 cases the values from EN are used without any changes In paragraph NA 2.10 is recommended, especially by halls for snow and wind load, during fire attack to apply the frequent value of live load ψ 1,1 Q 1 DIF SEK Part 1: Thermal & Mechanical Actions 50 / 50

52 Thank you for your attention DIF SEK Part 1: Thermal & Mechanical Actions