PART 1 THERMAL & MECHANICAL ACTIONS - - PowerPoint PPT Presentation

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PART 1 THERMAL & MECHANICAL ACTIONS - - PowerPoint PPT Presentation

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PART 1 THERMAL & MECHANICAL ACTIONS Part 1: Thermal & Mechanical Actions 0 / 50 Background of the RFCS Project DIFISEK+ Background of the RFCS Project DIFISEK+ This

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SLIDE 1

Part 1: Thermal & Mechanical Actions 0 / 50

  • PART 1

THERMAL & MECHANICAL ACTIONS

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SLIDE 2

Part 1: Thermal & Mechanical Actions 1 / 50

  • Background of the RFCS Project DIFISEK+

Background of the RFCS Project DIFISEK+

This project is funded by the European Commission in the frame

  • f the “Research Fund for Coal and Steel”

The aim of DIFISEK+ is to promote different projects of the last decades that dealt with fire engineering and, which results have been implemented in the EN 1991-1-2. 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

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SLIDE 3

Part 1: Thermal & Mechanical Actions 2 / 50

  • Treated Topics

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

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SLIDE 4

Part 1: Thermal & Mechanical Actions 3 / 50

  • 4: Thermal

response

time

R 5: Mechanical response 6: Possible collapse

Resistance to Fire - Chain of Events Resistance to Fire - Chain of Events

time

Θ Θ Θ Θ 2: Thermal action 3: Mechanical actions

Loads

Steel columns

1: Ignition

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SLIDE 5

Part 1: Thermal & Mechanical Actions 4 / 50

  • Thermal action on structure

Thermal action on structure

Composite Slab 1 side exposed Column 4 sides exposed

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SLIDE 6

Part 1: Thermal & Mechanical Actions 5 / 50

  • Heat transfer at surface
  • f building elements

Heat transfer at surface

  • f building elements

Exposed side Non-exposed side

h h h

r net net,c net

& &

&

,

+ =

Net Convective Heat Flux Net Radiative Heat Flux Total net Heat Flux

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SLIDE 7

Part 1: Thermal & Mechanical Actions 6 / 50

  • Structural Fire Safety Engineering
  • vs. Classification

Structural Fire Safety Engineering

  • vs. Classification

standard fire natural fire classification fire safety eng. fire safety eng. fire safety eng.

Prescriptive Performance based

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SLIDE 8

Part 1: Thermal & Mechanical Actions 7 / 50

  • Actions on Structures Exposed to Fire

EN 1991-1-2 - Prescriptive Rules Actions on Structures Exposed to Fire EN 1991-1-2 - Prescriptive Rules

Prescriptive Rules

(Thermal Actions given

by Nominal Fire)

Performance-Based Code

(Physically based Thermal Actions)

Design Procedures

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SLIDE 9

Part 1: Thermal & Mechanical Actions 8 / 50

  • Nominal Temperature-Time Curve

Nominal Temperature-Time Curve

*) Advanced Fire Models

  • Two-Zone Model
  • Combined Two-Zones and One-Zone fire
  • One-Zone Model
  • CFD
  • Parametric Fire

Localised Fire Fully Engulfed Compartment

θ θ θ θ (x, y, z, t) θ θ θ θ (t) uniform in the compartment

Standard temperature-, External fire - & Hydrocarbon fire curve

  • HESKESTADT
  • HASEMI

No data needed Rate of heat release Fire surface Boundary properties Opening area Ceiling height + Exact geometry *) Nominal temperature-time curve *) Simplified Fire Models

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SLIDE 10

Part 1: Thermal & Mechanical Actions 9 / 50

  • Prescriptive Fire Regulations Defining

ISO Curve Requirements Prescriptive Fire Regulations Defining ISO Curve Requirements

* does not consider the PRE-FLASHOVER PHASE * Does not depend on FIRE LOAD and VENTILATION CONDITIONS 200 400 600 800 1000 1200 30 60

θ θ θ θ [°

C] 90 120 180

ISO-834 Curve (EN1364 -1)

Time [min]

ISO ISO ISO ISO ISO ISO ISO ISO

The ISO curve * Has to be considered in the WHOLE compartment, even if the compartment is huge * Never goes DOWN 1110 945 1006 1049 842

T = 20 + 345 log (8 t + 1)

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SLIDE 11

Part 1: Thermal & Mechanical Actions 10 / 50

  • Temperature

Cooling ….

ISO834 standard fire curve

Ignition - Smouldering Pre- Flashover Heating Post- Flashover 1000-1200° C

Natural fire curve

Time Flashover

Stages of a Natural Fire and the Standard Fire Curve Stages of a Natural Fire and the Standard Fire Curve

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SLIDE 12

Part 1: Thermal & Mechanical Actions 11 / 50

  • Sprayed Protection

Sprayed Protection

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SLIDE 13

Part 1: Thermal & Mechanical Actions 12 / 50

  • Partially Encased Beams & Columns

Partially Encased Beams & Columns

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SLIDE 14

Part 1: Thermal & Mechanical Actions 13 / 50

  • Prescriptive Rules

(Thermal Actions given

by Nominal Fire)

Performance-Based Code

(Physically based Thermal Actions)

Actions on Structures Exposed to Fire EN 1991-1-2 - Performance Based Code Actions on Structures Exposed to Fire EN 1991-1-2 - Performance Based Code

Design Procedures

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SLIDE 15

Part 1: Thermal & Mechanical Actions 14 / 50

  • Some National Fire Regulations

include now alternative requirements based on Natural Fire Implemented in:

  • EN 1991-1-2

200 400 600 800 1000 1200 30 60 90

θ θ θ θ [°C]

120 180 Time [min]

I S O c u r v e

Natural Fire Safety Concept Natural Fire Safety Concept

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SLIDE 16

Part 1: Thermal & Mechanical Actions 15 / 50

  • NFSC Valorisation Project

NFSC Valorisation Project

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SLIDE 17

Part 1: Thermal & Mechanical Actions 16 / 50

  • Natural Fire Model

Natural Fire Model

*) Advanced Fire Models

  • Two-Zone Model
  • Combined Two-Zones and One-Zone fire
  • One-Zone Model
  • CFD
  • Parametric Fire

Localised Fire Fully Engulfed Compartment

θ θ θ θ (x, y, z, t) θ θ θ θ (t) uniform in the compartment

Standard temperature-, External fire - & Hydrocarbon fire curve

  • HESKESTADT
  • HASEMI

No data needed Rate of heat release Fire surface Boundary properties Opening area Ceiling height + Exact geometry *) Nominal temperature-time curve *) Simplified Fire Models

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SLIDE 18

Part 1: Thermal & Mechanical Actions 17 / 50

  • List of needed Physical Parameters for

Natural Fire Model List of needed Physical Parameters for Natural Fire Model

Boundary properties Ceiling height Opening Area Fire surface Rate of heat release

Geometry Fire

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SLIDE 19

Part 1: Thermal & Mechanical Actions 18 / 50

  • Characteristics of the Fire Compartment

Characteristics of the Fire Compartment

Fire resistant enclosures defining the fire compartment according to the national regulations Material properties of enclosures: c, ρ, λ , ρ, λ , ρ, λ , ρ, λ Definition of Openings

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SLIDE 20

Part 1: Thermal & Mechanical Actions 19 / 50

  • Occupancy

Fire Growth Rate RHR

f

[kW/m²]

Fire Load q

f,k

80% fractile

[MJ/m²]

Dwelling Medium 250 948 Hospital (room) Medium 250 280 Hotel (room) Medium 250 377 Library Fast 500 1824 Office Medium 250 511 School Medium 250 347 Shopping Centre Fast 250 730 Theatre (movie/cinema) Fast 500 365 Transport (public space) Slow 250 122

Characteristic of the Fire for Different Buildings Characteristic of the Fire for Different Buildings

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SLIDE 21

Part 1: Thermal & Mechanical Actions 20 / 50

  • Fire Load Density

Fire Load Density

1,90 2,00 2,13 Danger of Fire Activation Compartment floor area Af [m²] 1,50 1,10 25 250 2500 5000 10000

δ δ δ δq1

0,78 1,00 1,22 1,44 1,66 Danger of Fire Activation

δ δ δ δq2

Examples

  • f

Occupancies

Art gallery, museum, swimming pool Residence, hotel, office Manufactory for machinery & engines Chemical laboratory, Painting workshop Manufactory of fireworks

  • r paints

Automatic Water Extinguishing System Independent Water Supplies Automatic fire Detection & Alarm by Heat by Smoke Automatic Alarm Transmission to Fire Brigade

Function of Active Fire Safety Measures

δ δ δ δni

1 2 Automatic Fire Suppression Automatic Fire Detection δ δ δ δ n1 δ δ δ δ n2 δ δ δ δ n3 δ δ δ δ n4 δ δ δ δ n5 0,61 0,87 or 0,73 0,87 1,0 0,87 0,7 Work Fire Brigade Off Site Fire Brigade Safe Access Routes Fire Fighting Devices Smoke Exhaust System δ δ δ δn10 Manual Fire Suppression δ δ δ δ n6 δ δ δ δn7 δ δ δ δ n8 δ δ δ δn9 0,61 or 0,78 0,9 or 1 1,5 1,0 1,5 1,0 1,5

k f ni q q d f

q m q

, 2 1 ,

. . . .

∏

= δ δ δ

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SLIDE 22

Part 1: Thermal & Mechanical Actions 21 / 50

  • Rate of Heat Release Curve

Stationary State and Decay Phase Rate of Heat Release Curve Stationary State and Decay Phase

RHR [MW] Time [min] tdecay

Decay phase 1 2 3 4 5 6 7 8 9 10 5 10 15 20 25 30 t [min] x RHR Af

f

x RHR f Af COMPARTMENT FIRE Ventilation Controlled Fire

RHR [MW]

Steady state 70% (qf,d • Afi) Decay Phase

1 2 3 4 5 6 7 8 9 10 5 10 15 20 t [min]

RHR [MW]

75''

Fast (FGR) Medium (FGR)

Fire Growth Rate = FGR

Slow (FGR) Ultra- Fast (FGR)

150'' 600'' 300''

Growing phase

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SLIDE 23

Part 1: Thermal & Mechanical Actions 22 / 50

  • Natural Simplified Fire Model

Natural Simplified Fire Model

*) Advanced Fire Models

  • Two-Zone Model
  • Combined Two-Zones and One-Zone fire
  • One-Zone Model
  • CFD
  • Parametric Fire

Localised Fire Fully Engulfed Compartment

θ θ θ θ (x, y, z, t) θ θ θ θ (t) uniform in the compartment

Standard temperature-, External fire - & Hydrocarbon fire curve

  • HESKESTADT
  • HASEMI

No data needed Rate of heat release Fire surface Boundary properties Opening area Ceiling height + Exact geometry *) Nominal temperature-time curve *) Simplified Fire Models

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SLIDE 24

Part 1: Thermal & Mechanical Actions 23 / 50

  • FULLY ENGULFED

COMPARTMENT

θ θ θ θ (t) uniform in the compartment

LOCALISED FIRE

θ θ θ θ (x, y, z, t)

Simplified Fire Models Localised Fire Simplified Fire Models Localised Fire

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SLIDE 25

Part 1: Thermal & Mechanical Actions 24 / 50

  • Real Localised Fire Test

Real Localised Fire Test

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SLIDE 26

Part 1: Thermal & Mechanical Actions 25 / 50

  • Annex C of EN 1991-1-2:
  • Flame is not impacting the ceiling of a compartment (Lf < H)
  • Fires in open air

The flame length Lf of a localised fire is given by :

Flame axis L z D f H

Θ(z) = 20 + 0,25 (0,8 Qc)2/3 (z-z0)-5/3 ≤ 900° C Lf = -1,02 D + 0,0148 Q2/5

Localised Fire: HESKESTAD Method Localised Fire: HESKESTAD Method

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SLIDE 27

Part 1: Thermal & Mechanical Actions 26 / 50

  • Annex C of EN 1991-1-2:
  • Flame is impacting the ceiling (Lf > H)

Y = Height of the free zone concrete slab

θ θ θ θg

θ

x

= Air Temperature at Beam Level Calculated by CaPaFi

Localised Fire: HASEMI Method Localised Fire: HASEMI Method

beam

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SLIDE 28

Part 1: Thermal & Mechanical Actions 27 / 50

  • FULLY ENGULFED

COMPARTMENT

θ θ θ θ (t) uniform in the compartment

LOCALISED FIRE

θ θ θ θ (x, y, z, t)

Simplified Fire Models Fully Engulfed Compartment Simplified Fire Models Fully Engulfed Compartment

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SLIDE 29

Part 1: Thermal & Mechanical Actions 28 / 50

  • Real Fire Test Simulating an Office Building

Real Fire Test Simulating an Office Building

Fully engulfed fire

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SLIDE 30

Part 1: Thermal & Mechanical Actions 29 / 50

  • Annex A of EN 1991-1-2

100 200 300 400 500 600 700 800 900 1000 1100 10 20 30 40 50 60 70 80 90 100 110 120 time [min]

O = 0.04 m ½ O = 0.06 m ½ O = 0.10 m ½ O = 0.14 m ½ O = 0.20 m ½

Iso-Curve

Fully Engulfed Compartment Parametric Fire Fully Engulfed Compartment Parametric Fire

Temperature [° C] For a given b, qfd, At & Af

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SLIDE 31

Part 1: Thermal & Mechanical Actions 30 / 50

  • Natural Advanced Fire Model

Natural Advanced Fire Model

*) Advanced Fire Models

  • Two-Zone Model
  • Combined Two-Zones and One-Zone fire
  • One-Zone Model
  • CFD
  • Parametric Fire

Localised Fire Fully Engulfed Compartment

θ θ θ θ (x, y, z, t) θ θ θ θ (t) uniform in the compartment

Standard temperature-, External fire - & Hydrocarbon fire curve

  • HESKESTADT
  • HASEMI

No data needed Rate of heat release Fire surface Boundary properties Opening area Ceiling height + Exact geometry *) Nominal temperature-time curve *) Simplified Fire Models

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SLIDE 32

Part 1: Thermal & Mechanical Actions 31 / 50

  • Advanced fire Models

Advanced fire Models

LOCALISED FIRE LOCALISED FIRE FULLY ENGULFED COMPARTMENT The Fire stays localised The Fire switch to a fully engulfed fire

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SLIDE 33

Part 1: Thermal & Mechanical Actions 32 / 50

  • Large Compartment Test

Fire Load Large Compartment Test Fire Load

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SLIDE 34

Part 1: Thermal & Mechanical Actions 33 / 50

  • Large Compartment Test

External Flaming During the Test Large Compartment Test External Flaming During the Test

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SLIDE 35

Part 1: Thermal & Mechanical Actions 34 / 50

  • Large Compartment Test

After the Test Large Compartment Test After the Test

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SLIDE 36

Part 1: Thermal & Mechanical Actions 35 / 50

  • Two Zone Calculation Software “OZone V2.2”

Two Zone Calculation Software “OZone V2.2”

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SLIDE 37

Part 1: Thermal & Mechanical Actions 36 / 50

  • OZone results: Input and Computed RHR

OZone results: Input and Computed RHR

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SLIDE 38

Part 1: Thermal & Mechanical Actions 37 / 50

  • OZone results: Gas Temperatures

OZone results: Gas Temperatures

θHot θCold

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SLIDE 39

Part 1: Thermal & Mechanical Actions 38 / 50

  • OZone results: Smoke Layer Thickness

OZone results: Smoke Layer Thickness

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SLIDE 40

Part 1: Thermal & Mechanical Actions 39 / 50

  • Calibration of Software OZone: Gas Temp

Calibration of Software OZone: Gas Temp

200 400 600 800 1000 1200 1400 200 400 600 800 1000 1200 1400 TEST [° C] OZone [° C] MAXIMUM AIR T EMPERATURE OZone MAXIMUM AIR T EMPERATURE IN THE COMPARTMENT

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SLIDE 41

Part 1: Thermal & Mechanical Actions 40 / 50

  • Calibration of Software OZone: Steel Temp

Calibration of Software OZone: Steel Temp

200 400 600 800 1000 1200 1400 200 400 600 800 1000 1200 1400 TEST [° C] OZone [° C] UNPROTECTED STEEL TEMPERATURE

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SLIDE 42

Part 1: Thermal & Mechanical Actions 41 / 50

  • Influence of the Actives Fire Safety Measures

100 200 300 400 500 600 700 800 900 1000 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150

Time [min] Gas temperature [° C]

k , f i ni q1 d , f

q m q

∏ ∏ ∏ ∏δ

δ δ δ δ δ δ δ δ δ δ δ =

q2

No Fire Active Measures Off Site Fire Brigade Automatic Fire Detection & Alarm by Smoke Automatic Alarm Transmission to Fire Brigade Automatic Water Extinguishing System Design Fire Load [ MJ/m² ] q f,d = 291,2 m² Af Office :

625 356 310 189

= 511 MJ/m² q f,k ; Fire Load O.F. = 0,04 m½

OZone: Case Study OZone: Case Study

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SLIDE 43

Part 1: Thermal & Mechanical Actions 42 / 50

  • Grid

definition

Computer Fluid Dynamics: Software Sofie Computer Fluid Dynamics: Software Sofie

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SLIDE 44

Part 1: Thermal & Mechanical Actions 43 / 50

  • Sofie Results: Gas Temperatures

Sofie Results: Gas Temperatures

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SLIDE 45

Part 1: Thermal & Mechanical Actions 44 / 50

  • 4: Thermal

response

time

R 5: Mechanical response 6: Possible collapse

Resistance to Fire - Chain of Events Resistance to Fire - Chain of Events

time

Θ Θ Θ Θ 2: Thermal action 3: Mechanical actions

Loads

Steel columns

1: Ignition

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SLIDE 46

Part 1: Thermal & Mechanical Actions 45 / 50

  • Basis of Design and Actions on Structures

Basis of Design and Actions on Structures

S G Q

Fire

W

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

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SLIDE 47

Part 1: Thermal & Mechanical Actions 46 / 50

  • Room temperature

∑ γ ψ + γ + γ =

i Q,i 0,i 1 Q,1 G d

Q Q G E 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

Combination Rules for Mechanical Actions EN 1990: Basis of Structural Design Combination Rules for Mechanical Actions EN 1990: Basis of Structural Design

i >1

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SLIDE 48

Part 1: Thermal & Mechanical Actions 47 / 50

  • Fire conditions ≡ Accidental situation

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

Combination Rules for Mechanical Actions EN 1990: Basis of Structural Design Combination Rules for Mechanical Actions EN 1990: Basis of Structural Design

+ ψ + =

1 fi,d

∑ ψ

i >1 i 1or2,i

Q Q G E

1or2,1

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SLIDE 49

Part 1: Thermal & Mechanical Actions 48 / 50

  • Values of ψ

ψ ψ ψ factors for buildings Values of ψ ψ ψ ψ factors for buildings

Action ψ0

1 2

Imposed loads in buildings, category (see EN 1991-1.1) 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, 30 kN < vehicle weight ≤ 160kN 0,7 0,7 0,7 0,7 1,0 0,7 0,7 0,5 0,5 0,7 0,7 0,9 0,7 0,5 0,3 0,3 0,6 0,6 0,8 0,6 0,3 Snow loads on buildings (see EN1991-1.3) Finland, Iceland, Norway, Sweden Remainder of CEN Member States, for sites located at altitude H > 1000 m a.s.l. Remainder of CEN Member States, for sites located at altitude H ≤ 1000 m a.s.l. 0,70 0,70 0,50 0,50 0,50 0,20 0,20 0,20 Wind loads on buildings (see EN1991-1.4) 0,6 0,2 Temperature (non-fire) in buildings (see EN1991-1.5) 0,6 0,5

( Reference : EN1990 - February 2002)

Category H : roofs

ψ ψ

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SLIDE 50

Part 1: Thermal & Mechanical Actions 49 / 50

  • Load Factor

Load Factor

l k l Q k G l k fi k fi

Q G Q G

, , ,

γ γ ψ η + + =

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 50 100 150 200 250 300 350 400 Massivity Am/V [1/m] Load Factor E

fi,d / R fi,d,t [-]

Maximal Load level after R30

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SLIDE 51

Part 1: Thermal & Mechanical Actions 50 / 50

  • Thank you for your attention

Thank you for your attention Thank you for your attention