Fire Design of Aluminium Structures.pdf

8/10/2019 Fire Design of Aluminium Structures.pdf

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Fire Designof Aluminium Structures

Frantiek Wald

Czech Technical University in Prague


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European Erasmus Mundus

Master Course

Sustainable Constructions

under Natural Hazards

and Catastrophic Events

Introduction

PropertiesThermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

2

Objectives of the lecture

Summary of structural aluminium and steel design

at ambient temperature

Properties of structural aluminium

Particularities of aluminium fire design


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Master Course




Introduction

PropertiesThermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

3

Outline of the lecture

Introduction Thermal properties Mechanical properties Transfer of heat

Unprotected elements

Protected elements Elemental analyses Classification of sections Columns

Beams Critical temperature Summary

Worked example


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Master Course




Introduction

PropertiesThermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

Structural aluminium/steel behaviour?

Ambient temperature

Stress-strain diagram

No yield stress

Modulus of elasticity 1/3 of steel

Lower ductility

Different production of sections

Majority wrought aluminium

Buckling curves more favourable

Heat affected zones HAZ

Reduction of material properties


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Master Course




Introduction

PropertiesThermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

Structural aluminium/steel design?

Ambient temperature

Diferent procedures

HAZ for resistance

HAZ for stability

Lugs for stiffening

Material model


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Introduction

PropertiesThermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

Structural aluminium/steel design?

Ambient temperature

Standards different structure

EN 1999 Design of Aluminium Structures: EN 1999-1-1 General structural rules

EN 1999-1-2 Structural fire design

EN 1999-1-3 Structures susceptible to fatigue EN 1999-1-4 Cold-formed structural sheeting.

EN 1999-1-5 Shell structures


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Introduction

PropertiesThermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

7

Relative thermal elongation

As a function of the temperature


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Introduction

PropertiesThermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

8

Relative thermal elongation

Mathematical model


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Introduction

PropertiesThermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

9

Specific heat of aluminium

0

200

400

600

800

1000

1200

1400

0 200 400 600 800 Teplota, C

prEN 1999-1-2

Mrn teplo, J/ (kg K)

Tavenina

As a function of the temperature

Liquid alloy

Temperature, C

Specific heat J/kg K


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Introduction

Properties

Thermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

10

Specific heat of aluminium

200

600

800

1000

1200

0

400

5004003002001000

al/ C

cal

/ (J/kgC)

alc

Mathematical model


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Master Course




Introduction

Properties

Thermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

11

Thermal conductivity

of aluminium alloyal

The thermal conductivity for 0 C <

< 500 C

0

50

100

150

200

250

0 100 200 300 400

Tepeln vodivost, W m K

Teplota, C

5000 a 7000

-1 -1

ada 1000, 3000 a 6000

ada 2000, 4000,

Series

Temperature, C

Thermal conductivity, W/m K

Series


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Master Course




Introduction

Properties

Thermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

12

Thermal conductivity

Mathematical model

50

150

200

250

0

100

5004003002001000

al

/ C

al

/ (W/mC) A

B


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Introduction

Properties

Thermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

13

Mechanical properties

of aluminium alloys

At 20 C should be taken as those givenin EN 1999-1-1 for normal temperature design

For up to 2 hours thermal exposure period

0,2 % proof strength at elevated temperature

fo, = ko,fowhere

fo, is 0,2 proof strength at elevated temperature

fo is 0,2 proof strength at room temperature

according to EN 1999-1-1


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Introduction

Properties

Thermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

14

0,2 % proof strength

at elevated temperature

0,2% proof strength ratios ko,

Two tables Lower limits

Aluminium alloy temperature C

20 100 150 200 250 300 350 550

Lower limit values 1,00 0,90 0,75 0,50 0,23 0,11 0,06 0


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Introduction

Properties

Thermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

15



0,2% proof strength ratios ko,

Two tables for different alloys and tempers

0

0,1

0,3

0,4

0,5

0,6

0,7

0

0,2

0,8

1,0

0,9

500400300200100

6061-T66063-T5

E

6063-T6

6082-T6

6082-T4

al

/ C

ko,

Eal,

Eal

3004-H34


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Master Course




Introduction

Properties

Thermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

16



0,2 % proof strength ratios ko,

Two tables for different alloys and tempers

0

0,1

0,3

0,4

0,5

0,6

0,7

0

0,2

0,8

1,0

0,9

500400300200100

5454-O

E

5005-O

5005-H14

5083-H12

5052-H34

al

/ C

ko,

Eal,

Eal

5454-H34

5083-O


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Introduction

Properties

Thermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

17

Exposure period

300

200

400

100

015 30 60 3600

log min.

200 C

160 C

250 C

300 C Doba vystaven prvku

Mez mrnosti, MPa

zven teplot,

prEN 1999-1-2: 2004

Time of

exposure

log min

0,2 proof strengthfo, N/mm2

Time

of

exposure

log min


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Introduction

Properties

Thermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

18

Modulus of elasticity Eal,

Ratio E = Eal,/Eal for aluminium alloys

at elevated temperature al CAluminium alloy

temperature,

(C)

Modulus of elasticity,

Eal,

(N/mm)

20 70 00050 69 300

100 67 900

150 65 100

200 60 200250 54 600

300 47 600

350 37 800

400 28 000550 0


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Master Course




Introduction

Properties

Thermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

19

Modulus of elasticity Eal,

Ratio E = Eal,/Eal for aluminium alloys

at elevated temperature al C

0

0,1

0,3

0,4

0,5

0,6

0,7

0

0,2

0,8

1,0

0,9

500400300200100

5454-O

E

5005-O

5005-H14

5083-H12

5052-H34

al

/ C

ko,

Eal,

Eal

5454-H34

5083-O


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Master Course




Introduction

Properties

Thermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

Assessment 1

What thermal exposure is expected for

aluminium alloys during fire? When starts at elevated temperature the

reduction of 0,2 % proof strength?

20


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Introduction

Properties

Thermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

21

Unprotected aluminium

temperature development

Simple analytical model

Step by step procedure (the lumped mass method)

should not be taken as more than 5 s

Am/V the section factor should not be taken as less than 10 m-1


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Introduction

Properties

Thermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

22

Section factor

for unprotected aluminium members


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Introduction

Properties

Thermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

23

Section factor



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Introduction

Properties

Thermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

24

Section factor



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Introduction

Properties

Thermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

25

Grooves with gap in the surface

The calculation of the exposed surface area

Grooves with gap in the surface less than 20 mm

should not be included in the exposed surface

area.

Grooves with gap in the surface > 20 mm,

the area of the groove should be includedin the area of the exposed area

< 20 mm > 20 mm


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Introduction

Properties

Thermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

26

Surface emissivity m

The values of net,dshould be obtained from EN 1991-1-2 using

m = 0,3 for clean uncovered surfaces

m= 0,7 for painted and covered

(e.g. sooted) surfaces

h


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Introduction

Properties

Thermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

27

Surface emissivity m

100

200

300

400

5 10 15 20 25

Teplota prvku , C

25A / V =m355075150200300 100125

150200300 125 3550100 25A / V =m

m= 0,7

0

0

m= 0,3

as, min.

Souinitel prezu

Time, min

Element

temparature, CSection factor


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Introduction

Properties

Thermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

Aluminium element

insulated by fire protection

materialFor a uniform temperature distribution

in a cross-section, the temperature increase

28


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Introduction

Properties

Thermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

Section factor Ap/V

for insulated members

29

Sketch Description Section factor (Ap/V)

Contour encasementofuniform thickness,exposed to fire on foursides.

areasection-crossaluminium

perimeteraluminium

b

h

Hollow encasement ofuniform thickness,

exposed to fire on foursides.


)+(2 hb


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Introduction

Properties

Thermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

Section factor Ap/V

for insulated members

30

b

Contour encasement of

uniform thickness,exposed to fire on threesides.


-perimeteraluminium b

b

h

Hollow encasement ofuniform thickness,exposed to fire on threesides.


+2 bh


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Introduction

Properties

Thermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

31

Design tools TALAT

Reference thickness of fire protection

dp = k dp,ref (k based on material form 0,4 to 1,4)

V

Ap

0

200

300

400

500

0 5 10 15 20 25 30

Teplota, C

=

= 25 m

100

200 300

150

200

300

-1V

Ap

10025

50

100

150

Tlouka po. ochr., ,mm

R 30

Porn

PornodolnostR 15 50

odolnost

dp

m-1


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Introduction

Properties

Thermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

Assessment 2

What differences are for step by step procedure

of aluminium compare to steel? Desribe the section factorAp/V

for insulated member by bords?

What surface emissivity m is expected forclean uncovered surface?

32


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Introduction

Properties

Thermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

Structural fire design

Simple calculation models

Efi,d Rfi,d,tEfi,d is the design effect of actions for the fire design situation

Rfi,d,t is the design resistance of the aluminium structure or

structural member, for the fire design situation

Advanced calculation models

The development and distribution of the temperature

within structural members (thermal response model);

The mechanical behaviour of the structure or of any partof it (mechanical response model).

Validation of advanced calculation models

33


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Introduction

Properties

Thermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

Effect of actions

For time t = 0

Using combination factors 1,1 or 2,1 according toEN1991-1-2

Efi,d =fi Ed

WhereEd is the design value of the correspondingforce or moment for normal temperature design

As a simplification the recommended value

of fi = 0,65 may be used(Except areas susceptible to accumulation of goods,

including access areas.)

34


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Sustainable Constructionsunder Natural Hazards


Introduction

Properties

Thermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

Classification of cross-sections

Classified as for normal temperature design

Based on the same relative drop in the 0,2 %proof strength and modulus of elasticity

Actual drop in modulus of elasticity

Classification of the section changes

Larger capacity value of the section

35

b ,


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Introduction

Properties

Thermal

Mechanical

Transfer of heat

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Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

coefficient

To introduce different materials

Plate slenderness

36

of/250=

=

==

kEf

t

b

kt

b

o

p

)2

2

1(12

4,28

==

=

kf

Et

b

kf

Et

b

kEf

t

b

o oo

950,0235

0620,0)1(12 2

2

k

t is plate thickness

b is width,

is Poisson ratio

E is modulus od elasticity

fo is 0,2 % proof strength

souinitel napt

b ,


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Introduction

Properties

Thermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

Reduction of coefficient

At elevated temperature

37

ksouinitel napt

oo

E

o

E

o, f

E

k

k

fk

Ek

f

E

o

==,

,

,

,

yyy,

E,

f

E

f

E

k

k

00,1

bk

,


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Introduction

Properties

Thermal

Mechanical

Transfer of heat

Unprotected

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Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes


for structural steel

38

ksouinitel napt

I t d ti

bk

,


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Introduction

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Elemental analyses

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Beams

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Critical temp.

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Notes


for steel

39

ksouinitel napt

yyy,

E,,

f

E

f

E

k

k850

Currently for steel

, C0

0,2

0,4

0,6

0,8

1

1,2

0 200 400 600 800

,y,E k/k

,y,E k/k

539 C

766 C

0,85

368 C

436 C

1000

I t d ti

bk

,


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Introduction

Properties

Thermal

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Unprotected

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Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes


for aluminium


40

ksouinitel napt

0f

250=

oo,

alal,,

/

/

ff

EE

= o,

alE,

k

k

Introduction

bk

,


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Introduction

Properties

Thermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes


for aluminium

41

ksouinitel napt

0f

250=

Introduction

b

k

,


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Introduction

Properties

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Elemental analyses

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Beams

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Critical temp.

Summary

Worked example

Notes


for aluminium

42

ksouinitel napt

0f

250=

Introduction


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Introduction

Properties

Thermal

Mechanical

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Unprotected

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Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

Tension members

The design resistance

Nfi,t,Rd = Ai ko,,ifo / M,fi

where

Ai is an elemental area of the net cross-section

with a temperature i , including a deduction ifrequired to allow for the effect of HAZ

softening.

The deduction is based on the reduced thicknessof o,HAZt

ko,,i is the reduction factor for the effective 0,2 %

proof strength at temperature i. 43

Introduction


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Introduction

Properties

Thermal

Mechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

Beams

The designMfi,t,Rd of a cross-section

in class 1, 2, 3 or 4

with a uniform temperature distribution at timet

Mfi,t,Rd = ko,MRd(Mx/M,fi)

where

MRd is the moment resistance of the cross-section fornormal temperature design.MRd is either Mc,Rdor Mu,Rd

Mx is the material coefficient according to EN 1999-1-1. M1is used in combination with Mc,Rd and M2 is used in

combination with Mu,Rd

The design resistance Mfi,t,Rd is given by the combination of

MRd and Mxwhich gives the lowest capacity.

44

Introduction


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Unprotected

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Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

Columns

The design buckling resistance Nb,fi,t,Rd of a

compression member at timet

Nb,fi,t,Rd = ko,,maxNb,Rd (M1/1,2 M,fi)

where

Nb,Rd is the buckling resistance for normal

temperature design according to EN 1999-1-1

1,2 is a reduction factor of the design resistance

due to the temperature dependent creep

of aluminium alloys

45

Introduction

B kli l th


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Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

Buckling length

of a column in intermediate storey

Braced frame in which each storey comprises

a separate fire compartment

with sufficient fire resistance

46

A: Shear wall or other bracing system

B: Separate fire compartments in each storey

C: Column buckling lengthD: Deformation mode in fire

Introduction


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Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

Relative slenderness

The same relative drop in the 0,2 % proof

strength and modulus of elasticity.

If the actual drop in modulus of elasticity is

taken into account, a larger capacity value can

be obtained.

47

=

oo,

alal,,

/

/

ff

EE

=

o,

alE,

k

k

Introduction


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Elemental analyses

Classification

Beams

Columns

Critical temp.

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Notes

48

Buckling curves

Buckling classes: A

1,2 is a reduction factor of the design resistance due to the

temperature dependent creep of aluminium alloys

0,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1,0

0,0 0,5 1,0 1,5 2,0

hlink

ocel

0,20 - tepeln upraven0,32 - tepeln neupraven

0,20 - tepeln upraven

0,32 - tepeln neupraven

0,21 - kivka a0,76 - kivka dZa poru

Pomrn thlost

Souinitel vzprnosti

redukce 1,2

Relative slenderness

Reduction factor for buckling

Aluminum

Steel

Class A

Class B

Class A

Class B

Curve a

Curve d1,2

reduction

for fire

design

Introduction

Buckling resistance


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Notes

49

nosnost, kN

60 x 60 x 4

0,0

20,0

40,0

60,0

80,0

100,0

120,0

140,0

160,0

180,0

200,0

0 20 40 60 80 100 120 140 160 180 200

thlost

f0= 250MPa ,

= 0,20; 00 =

Ocel S235

Slitina EN AW-6082

20 C

300C

T6, tepeln upraven;

200 C

fy= 235 MPa; = (kivka a)0,21

Buckling resistance


Buckling length od rectangular hollow section 60x60x4

Slenderness

Buckling resistance

Alloy EN AW 6082Temper T6

Steel S235

Introduction

The critical temperature


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of aluminium alloys

50

0

100

200

300

400

500

600

700

800

0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8

ocel

EN AW-5454EN AW-5086

EN AW-5083

EN AW-6082

EN AW-3003

Kritick teplota prvku , C

Stupe vyuit prezu, 0

170

Slitiny hlinku

Degree of utilisation0

Critical temperature C

Steel

Aluminium

Simplified value 170 C

Introduction



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of aluminium alloys

where the degree of utilisation0= Efi,d/ Rfi,d,0may not be taken lass than 0,015

Efi,d is the design effect of actions for the firedesign situation according to EN 1991-1-2 and

Rfi,d,0 is the corresponding design resistance of

the steel member for fire design situation at

time t.

The accuracy of the prediction varies is limited.

The prediction of critical temperature of steel

shows a deviation 3,73%. 51

B

A

lnCDcr,a

+

= 1

1

0

Introduction



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Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes


of aluminium alloys

Constants for calculation of critical temperature

of aluminium alloys

52

Alloy Thermaltreatment

Constants MaximaldeviationA B C D

EN AW-5052 O 0,9905 428 74,88 0,2063 14,7 %

EN AW-5052 H34 0,9797 420 90,06 0,1273 27,0 %

EN AW-5083 O 0,9942 430 62,53 0,1485 10,5 %EN AW-5083 H113 0,9843 424 89,97 0,2711 0,9 %

EN AW-5454 O 0,9885 424 74,01 0,1519 15,7 %EN AW-5454 H32 0,9806 422 85,83 0,1427 15,6 %

EN AW-6061 T6 0,9957 427 65,38 0,1169 1,8 %EN AW-6063 T6 0,9902 422 74,06 0,1048 8,7 %EN AW-6082 T6 0,9826 420 89,37 0,1377 4,6 %EN AW-3003 O 0,9806 424 95,59 0,3199 4,5 %EN AW-3003 H14 0,9753 412 95,87 0,1263 9,4 %

EN AW-5086 O 0,9843 424 89,97 0,2711 0,8 %EN AW-5086 H112 0,9826 428 78,80 0,2438 19,6 %

EN AW-7075 T6 0,9763 412 94,12 0,1143 12,0 %

ECCS nomogram for aluminium


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53

g

50125 3575

-1

100150200300

200

250

300

350

400

450

500

150

100

Kritick teplota, ,Cal,cr mAm/ V

100

200

150

250

300400

500

600

700

800

900

1000

1200

1500

2000

5 10 15 20 250,0

50

0,10,20,30,40,50,60,70,8

0

)(Ap/ V /( p/ dp ) W K m-3

25EN AW -3003

EN AW -5083EN AW -6061

EN AW -6082EN AW -7075

EN AW -5086

EN AW -5454

-1

170

as, min.

Souinitel prezu,

Stupe vyuit prezu,

Pokud teplota nepekro

nen teba posuzovat

Utilisation

Section factorCritical temperature

Time, min

Critical temperature

Reduction of material Transfer of heat

Introduction


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Master Course



Properties

ThermalMechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

Assessment 3

What advantage may be utilesed for

classification of aluminium cross-sections?

How is treated the temperature dependent

creep of aluminium alloys for simple modelling

of buckling resistance?

What is the simplified value of critical

temperature of aluminium alloys?

54

Introduction


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Master Course



Properties

ThermalMechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

55

Summary

EN1999-1-2 first standard for fire design of aluminium str.

Based on steel knowledge

Lower fire resistance compare to steel

The low melting point of aluminum (590 C a 650 C)

The good emisivity 0,3

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,91

0 200 400 600 800 1000 Teplota, C

Smluvn mez kluzu oceli

Redukn souinitel

Mez mrnosti hlinkovch slitin

Reduction factor

Steel - effective yield strength ratio

ky,

Aluminium - 0,2 % proof strength ratios ko,

Temperature, C

Introduction

W k d l b l


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Master Course



Properties

ThermalMechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

Worked example beam column

Laterally restrained beam

Load (gk + qk) 2 kN/m

Load reduction factor F = 1,45 Alloy EN AW-5083 (material class B)

56

Section classification


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Section classification

Flage in compression not decide

Web in compression stiffened plate

is taken form diagram 6.4 in EN 1999-1-1

Web and all section Class 4

Web in bending

section asymmetry coefficient

varying the stress coefficient g

Web and all section Class 1 57

3

1800,95 34,2 18 18 1,51 27,1

5

b

t = = = > = = =

1

1800,95 0,351 12,0 13 13 1,63 21,1

5

bg

t = = = < = = =

Effective section


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Effective section

Reduction factor for web in compression

material buckling class B

Effective area

Shift of the center of gravity due to buckling

58

( ) ( )1 2

c 2 229 198 0,894

180 5 180 5C C

b t b t = = =

( ) ( ) 2eff g c1 2 3848 1 0,894 2 180 5 3752 mmA A b t= = =

( ) ( )

ct

eff

1801 0,894 2 180 5 83

1 2 20,36 mm

3752

b t zz

A

= = =

R i t h k


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Resistance check

Section bending resistance

Section poor compression resistance

Buckling factor

Combination of buckling and pure bending

OK

59

( ) ( )

c 0,8

Ed Ed

Rd y,Rd

c min

27,9 15,30,895 1,0

0,483 375,2 22,8

kde max 0,8;1,3 max 0,8;1,3 0, 483 0,8

N M

N M

+ = + =


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Serviceability check

Full gross section

Due to lower stessess no local bucklingWeb in compresion

Simplified

Secant modulus of eleasticity for maximal stressRamberg-Osgood material model

OK

3

s 53Ed,ser

Ed,ser 0

70 10

61 022 MPa70 10 55,81 0,0021 0,00255,8 110

n

E

E E

f

= = =

++


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Mechanical actions at fire

Reduction factor fi

For snow loading 1,1 = 0,2

321051331351660

33120660,

,,,,

,,,

QG

QG

QkGk

k1,1kfi =+

+=

+

+=

kNm9143210315 ,,,MM fiEdEd,fi ===

kN9683210927 ,,,NN fiEdEd,fi ===

Termal loading during fire


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g g

Annex E standard EN 1991-1-2:2004

Rate of heat release Q

35302520151050

0,5

0

1,5

1,0

2,5

2,0

3,5

3,0

4,0

as, min

Rychlost uvolovn tepla, MWRate of heat release, MW

Time, min

Thermal heat during fire


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g

Flame heigt in time t

Diameter of the fire in timet

Temperature along the flame axesConvective part of the rate of heat releaseQc

353025201510500

1,0

2,0

3,0

4,0

as, min

Dlka plamen, m

5,0

6,0 Flame heigt, m

Time, min


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Transfer of heat into structure


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Transfer of heat into structure

Maximal beam temperature 272 C in 22 min 40 s

Reduction factor for k0,,max= 0,596

0

50

0

150

100

250

200

350

300

400

3530252015105

Teplota, C

40as, min

teplota plyn

teplota nosnku

Temperature, C

Time, min

Gas

Beam

Resistance at elevated temperature


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p

Bending resistance

Buckling resistance

Buckling length as at ambint temperature

Interaction as at ambient temperature

OK

0147509514

914

099

968 80

,,,

,

,

,

M

M

N

N ,

Rd,t,fi

Ed,fi

Rd,t,fi,b

Ed,fi

c


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Master Course




Properties

ThermalMechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

68

List of Lessons at Seminar

1. Fire safety RZ

2. Fire and mechanical loading RZ

3. Thermal response RZ

4. Steel structures RZ5. Concrete structures JMF

6. Composite structures JMF

7. Advanced models JMF

8. Composite floors FW

9. Aluminium structures FW

10. Timber structures FW

11. After fire and Historical structures FW

12. Definitions of Design for Robustness JMD

13. Global response of structures JMD

14. Design recommendations JMD

15. Alternative load path method JMD


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Thank youfor your attention

Frantiek WALD

[email protected]

Introduction

Properties Notes to users of the lecture


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under Natural Hazardsand Catastrophic Events

Properties

ThermalMechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

70

Notes to users of the lecture

Further readings on the relevantdocuments from website of

www.eaa.net/eaa/education/TALAT

Keywords for the lecture:

fire design, aluminium structures,

material properties,

Introduction

Properties Notes to users of the lecture


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Master Course


under Natural Hazardsand Catastrophic Events

p

ThermalMechanical

Transfer of heat

Unprotected

Protected

Elemental analyses

Classification

Beams

Columns

Critical temp.

Summary

Worked example

Notes

Text books

Wang Y., Burgess I., Wald F., Gillie M.,

Performance Based Fire Engineering of StructuresCRC Press 2012, ISBN: 978-0-415-55733-7.

Buchanan A. H.,

Structural Design for Fire Safety,

Wiley, 2001, ISBN 0471889938.


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