ATEXTREME TEMPERATUREeprints.utm.my/id/eprint/8344/1/BadriAbdulGhani1996_Experimental... · Jurnal...

Jurnal Mekanikal, Jilid II, 1996

EXPERIMENTAL VERIFICATION OF COLUMN

AT EXTREME TEMPERATURE

Badri Abdul Ghani

Mohamed El-Shayeb

Department of Mechanics ofMaterials

Faculty of Mechanical Engineering

Universiti Teknologi Malaysia

T.T.Lie

Division of Building Research

National Research Council, Canada

ABSTRACT

Experimental studies have been carried out to predict the fire

resistance of protected I-shaped steel insulated with ceramic

fibre. The steel section selected were W250-80 and W310-158.

The experimental results are compared with those obtained using

the mathematical models develop by the same authors. The

results indicate that the model is capable ofpredicting the fire.

1.0 INTRODUCTION

Over the .years, various specimens of protected steel columns, insulated with heat

retardant material such as gypsum board, cementitious material and material fibre

were tested. For the purpose of verification of the model given in the research paper

[1], the results of tests on five columns with different cross-section sizes and

insulation thickness will be used for comparison with calculated results. The

columns were made of structural steel section blanketed with ceramic fibres that

35

Jurnal Mekanikal, Jilid tt. 1996

follow its contour. All columns were 3,810 mm long from endplate to endplate The

thickness of the insulation were from 1 inch, 1-112 inch and 2 inches applied on steel

section W250-80 and W315-58. All steel endplates were 25 mm thick. A specimen

is illustrated in Fig. 1 and Fig. 2. The earlier figure shows the cross-section of the 1

shape steel section and location of the thermocouple and strain gauges. The latter

shows the whole length of the column from endplate to endplate.

The steel for the columns was cut to appropriate lengths and then the end

plates were weld to the steel at column extremities. The centering and

perpendicularity of the end plates were given special attention to ensure a high

degree of accuracy. After welding the end plates, twelve holes with diameter of 7/8

inch were drilled in each endplate. The holes were created for studs of the furnace

compressor piston at the bottom and support at the top.

The steel of the column had a specified yield strength of 300 MPa and the

insulation does not contribute to the strength of the column. Chromel-alurnel

thermocouples with a thickness of 0.91 mm were installed at the mid-height of the

column for measuring the temperatures of the steel section at different locations in

the cross section. The locations of the thermocouples are described in National

Standard of Canada CANIULC-SI01-M89.

2.0 TEST APPARATUS

The tests were done by exposing the columns to heat in a column test furnace. The

test furnace was designed to produce the conditions to which member might be

subjected during a fire. It consists of a steel framework supported by four steel

columns with the furnace chamber inside the frame characteristics and

instrumentation of the furnace which has a loading capacity of 1,000 tonnes, are

described in detail in Ref. 13.

36

Jurnal Meka nikal, lilid II, J996

"55 0... <. ,- '._ . ' . ' .... . .__. .... . . . . - -- - . . . . _~/ '/I sol t! a.t. u»II , O.J.5

/ 'jee!. \_. _-... - ... ..:-=.t-. t? 7'

... ff / A t ,2 'n_.

I ".- ',' ·. :f ·/ / / / .•- :»

I~

6 5 .tI '0

~ -~~. ,

1-

J~ . 7

'" ,h1l (gt=", j~25.4 - /- ~ -'_ .• . ._- ---. ..-

--- . .. 7 - ~--- ,--_ . _. '._-- --..~.._- -_....

--- u = ..JL4r "'--

-f-r · ·-'(! ~JJL- ..

H.. ..~..L .,

I 1 1 1:2TOt .' " .' /

.' / , . / ,. / ; / r> .:19 8

...-~3~f- --lf-+._ _ .L?..7- 5__._ _

C>

<0' 0<:\1

Fig, 1 W2S0-80 Steel Section with 1 Inch Ceramic

25.4 mm

.L

Endplate

I'\

I\I

I\

\

\

I

II

III

m II

\II

~ - - --- -54~ Sq -·_-- - ~

T1905 m

J

3810 mm

Fig, 2 The Column Length

37

Jurnal Mekanikal, Jilid II, J996

3.0 TEST CONDITIONS AND PROCEDURES

The tests were done with both ends of the columns fixed i.e. restrained against

rotation and horizontal translation. The columns were tested under a concentric load.

The applied loads were from 59% and 86% of the factored compressive resistance of

the columnstCi) as determined according to the Canadian Standards Association

CSA/CAN-S 16.1-M89 {"Limit States" 1989). The factored compressive resistances

of each column, as well as the applied loads, are given in Table 1. The effective

length factor K used in the calculation of the factored compressive resistance was

that recommended in CSA/CAN-S 16.1-M89 for the given end condition, i.e., 0.65.

The effective length of the columns, KL, was thus assumed to be 2.48 m. However

previous test had indicated a more accurate effective length of 2.0 m because the

extreme ends of the column were not exposed to the fire intensity as much as the

middle part of the column.

Table 1 Factored Compressive and Applied Loads

Resistances of Each Column

Section-Code Insulation Factored Max. Applied RatioColumn and Sizes: Thickness Strength Allowable Load

No. G40.21-M Load300W mm (inch) Cr (kN) (O+L) kN C (kN) CICr

FSI W250 x 80 25 ( 1 ) 2550 1908 1750 0.69

FS2 W250 x 80 38 (1-1/2 ) 2550 1908 1700 0.67

FS3 W310 x 158 25 ( I ) 5098 3856 3000 0.59

FS4 W250 x 80 25 ( 1 ) 2550 1908 2200 0.86

FS5 W310 x 158 50 (2 ) 5098 3856 3800 0.75

D - dead load, L - live load

During the test, the column was exposed to heating in a controlled way that

the average temperature in the furnace followed as closely as possible, the ASTM

E119-88 or CANIULC-S101 standard temperature-time curve.

38


4.0 RESULTS AND DISCUSSIONS

Using the mathematical model described ill Ref. 1, the temperatures axial

deformations, and strengths of the columns were calculated. In the calculations, the

thermal and mechanical properties of the steel, given in Ref. 4, were used. The

ceramic thermal properties was provided by the supplier Unifrax Corporation.

In the calculation of the time of fire resistance for calculated data, the graph

of load capacity of column against time is used, failure occurs when load carrying

capacity equal to the applied load. The strength decreases with time until it becomes

so low that the column can no longer support the load. The time to reach this point is

the fire resistance of the column. Fire resistance for measured data are determined

when the axial expansion stop. This is because the test only produce data for

temperatures and axial deformation but does not produce load capacity data. Hence

the time for fire resistance is obtained using the graph of axial deformation against

time where failure occurs when the column stop increasing in length.

In Figs. 3 to 7, the calculated average temperatures [1] are compared with the

average temperatures measured at the external surface of the steel section. With the

exception of the test conducted on the column FS3, there is good agreement between

calculated and measured column temperatures. The temperatures measured initially

showed a relatively cautious rise up to temperatures of approximately 50°C,

followed by a period of relatively faster rate of temperature rise. This temperature

behaviour may be the result of the steel section having reach some equilibrium for a

particular time step after the initial cold start. As a whole, which are important from

the point of view of predicting the fire resistance of the columns there is a good

agreement between calculated and measured temperatures [1].

39


600

l/l::J'u 500(j)UOl~ 400

~.a 300l!!(\)c,

~ 200I-

100 .

20 30 40 50 60 70 80 89

Time, minutesAverage Temperature of Column FSl for Test and Calculated DataFig. 3

o .I---t---+----t----t----+----+----+----+----+----l

o 10

700

600

III 500 .:::)

'u~Cl 400~

€a 300e&.E~ 200'

100

l----· ·-------·~J--Test Celcius

-&- Calculated Celcius--------~~---~----_.._._._."----~

o 1----t--+--t--t-----.,i----I---+--+--+--+---+---+---+--_+_--I

o 10 20 30 40 50 60 70 80 90 100 110 120 129

Time, minutes

Fig. 4 Average Temperature of Column FS2 for Test and Calculated Data

40


700 -r------------------------I

600

III

·5 5004iog' 400"CI

€~ 300e8-E 200·Q)I-

100

0+=----+_-+-_+-----1--+---+--1----+--+--+----+---1-----1o 10 20 30 40 50 60 70 80 90 100 110 120

Time, minutes


700.------------------------------.

600

...-fi 500GiUg' 400"CI

€::::J 300!8-E 200~

100[- _ ._ ._- _.__ .._~

--Test

-<>- Calculated----~._-

888070605040302010

O+----I---+--+_--I---_+~-+_--t__-_+--_+_----l

oTime, minutes


41


700 ~.,...------------------------------,

--.._.._-----_._._-----~--~-

--Testl~~aJ~urate<l100

600

OI---+--+-l---+--+---l-+--+--+-l--+---+---+-+--+--+----t-+--+--+-----1

~

III~"u 500

~~ 4do't:I

~ 300eCI)

~ 200~

TIme, mInutesFig. 7 Average Temperature of Column FS5 for Test and Calculated Data

In Figs. 8 to 11, the calculated and measured axial deformations of the

columns during exposure to fire are shown. There is reasonably good agreement in

the trend of deformations between calculated and measured results [1]. There are

some differences, however, between the actual values of the calculated and measured

deformations.35.0 ,.----------------------------,

[--------------- ~- --]--Test (mm)

---<>- Calculated (mm)_._-_..._------_._----------_.-----------

30.0 -

25.0

~20.0

g15.0

iI§ 10.0

.emc 5.0-

iii~ 0.0 b--~:::::=..--t__-------+-------+--------t-- - ---t- -------+-- ... -----+----

10 20 30 40 50 60 70 80-5.0

-10.0

-15.0 _L- -----J

Time, minutesFig. 8 Test and Calculated Values for Axial Deformation of Column FSI

42

Jurnal Mekanikal, Ji/id 1I, J996

30.0 ·r-------------------------,

~---- _ ._---------~

- - Test (mm)

-0-- Calculated (mrn)_...--_. ~.._-- -_.---- .- ._----

0.0 O-"""""¥=- - -- ·-1-- ----\------ -+-- ·-- -/- -----\--- - -1-- -·- + ---- - -\----.+- - - ---t- --.

20 30 40 50 60 70 80 90 100 110

25.0

20.0

EE 15.0Co~ 10.0 .r

ioIi 5.0

~

-5.0

-10.0 .L- ---'

Time, minutes

Fig. 9 Test and Calculated Values for Axial Deformation of Column FS3

8070

[-- ---- -...-----.------.J- - Test (mm)

-0-- Calculated (mrn)-- - --.._- ,-- _ ...- -_.._--_ ..

6---.....'!-f-r:::- - -- --.--t-.- --- -.._- j-..-- --- ---(- - ·-- --- --t ····- - -- 1-··

10 20 30 40 50 60

30.0

25.0 -

20.0

E 15.0 · .EC

10.00

1iII)

\1 5.00Ii

~ 0.0

-5.0

-10.0

-15.0 ·

Time, minutes

Fig. 10 Test and Calculated Values for Axial Deformation of Column FS4

43

Jurnal Mekanikal, Jilid II, J996

30.0 .r-------------------------,

-+ ·!·_--+---I--+·····1--+--+-~t--+--+-+_·-+--t-·_--+·

b? re\:) co\:) ,,\:)\:) "rf> ~\:) "ro\:) "co\:)

[_ _---_ _._-----_._._~

--Test (rnrn)

-c>- Calculated (rnm)-_.,'"-,_..--._--_._. __ ._---~_._-_ .._.._~._ .....-20.0

25.0

-15.0

-10.0 .

E 15.0EC 10.0o=BCI) 5.0

~ 0.0 O-Oc""¥ii

~ -5:t[

-20.0 -'----------------------------'

Fig. 11

Time, minutes

Test and Calculated Values for Axial Deformation of Column FS5

It must be noted that the column deforms axially as a result of several factors

namely, load, thermal expansion, nding and creep. The last ones cannot be

completely taken into account in the calculations [1]. Since the axial deformations,

which are in the order of 20 mm, are for columns with a length of about 3800 mm,

small inaccuracies in these factors may cause noticeable differences between

calculated and measured axial deformations. A difference of 10% between the

theoretical and actual coefficients of thermal expansion of steels for example, will

cause a difference of approximately 5 mm in the axial deformations.

The effect of creep, which is more pronounced at the later stages of .fire

exposure, may be even greater. The model defines the failure point as the point at

which the column can no longer support the applied load and assumes that failure at

this point is instantaneous. During the tests, failure was not instantaneous but the

columns contracted considerably apparently as a result of continued loss of strength

and creep, before they were crushed.

44


In Figs. 12 to 16, the calculated column strengths, as a function of the fire

exposure time, are shown for the test loads given in Table 1. The results show that

the calculated fire resistance of column FS1, FS2 and FS5 are less than 5% off the

measured fire resistances. The specimens FS3 and FS4 showed a less accurate result

giving the value of 15% "and 20% respectively off the measured fire resistance. Lie

indicated that a 10% off the measure value is considered excellent validation but a

20% off in accuracy is still acceptable.

Coincidentally, the three column that produce the better results were the first

three specimens to be tested for its fire resistance in the furnace. There were

technical difficulties before the last two experiments that required rectification

which probably explained the less accurate results.

3200

3000

2800

2600 - Tim e v StrengthZJIl: -- TI m e v AvgTemp

:z: 2400I-C) 2200zwa:: 2000I-UJ

1800

1600

1400

1200

600

III

500~

'u'iio

400 u.ia::;:)I-

300 ~WD..

200 :IEwI-W

100C)

~W>

0 c(

o 20 40

TIME, min

60 80 100

Fig. 12 Column FSI

45

Jurnal Mekanikal, Jilid II. J996

3500 .,-------------------------"""T""

3000

Z 2500.:It:.

:E:I- ~ Tim e v Strength(!) 2000 -- Ti m e v AvgTempZW0:::I-U'J 1500

800

700 rn;:,'u

600Q)0u.i

500 0:::~I-

400 ~WQ.

300 :::EwI-

200 we

100 ~w>c(

0

o 20 40 60 80 100 120 140 160 180

TIME, min

Fig. 13 ColumnFS2

700

600III;:,"uQ)

500 0ui0:::

400 ~I-

~300 W

Q.

:::Ew

200 I-W(!)

100 ~W>

0 c(

~----;]- - Tim e v Strength-- T im e v AvgTemp

- - - - -

6000

7000 .....--- - - - - - - - - - - - - - - - - - - - - - - - ...

2000

:E:I-(!) 4000Zw0:::I-U'J 3000

Z 5000.:It:.

o 20 40 60 80 100 120 140 160

TIME, min

Fig. 14 Column FS3

46


600

III500 ~·u

QjU

400 W~

0::;:).I-

300 ~WQ.

.200 :EwI-W

100C)

~W>

0 ct

80 1006040

TIME, min

ColumnFS4

20

Fig. 15

o

3200

3000

2800

2600Z.lll:

::z::2400

I- -- Tim e v StrengthC) 2200 - TI mevAvgTempZW0: 2000I-en

1800

1600

1400

·1200

7000

6000

Z 5000.¥

Z - TI mevStrengthI-C) 4000 - TlmevAvgTempZW0:I-en 3000

2000

1000

0 50

Fig. 16

700

600 III~

U500

QjUu.i0:

400 :;:)I-

~300 w

Q.

:E

200wI-WC)

100 ~w>

0 ct

100 150 200 250

TlME, min

Column FS5

47Pt<.;.iU'USTAKAAN SULTANAH ZAN.AlUA.H

Universiti 'I'eknolozi Malavsis

Jurnal Mekanikal, Jilid II, /996

Other liable factor for the inaccuracy of the results is the considerable

contraction of the columns that the model can only partly take into account. In

addition, the properties of the materials applied in the model may not be the best

value to represent the specimens tested.

A factor that can severely affect the accuracy of the model is the mode of

fixing the column at each end to the furnace compressor and support. The actual

joints of the column during test is fixed end connection that could possibly give rise

to moment stress in the column but in the program, it is assumed to have pin-ended

joints and hence zero moment at both ends.

Another factor that can affect the accuracy of the program is that, the

instantaneous crushing of the column tend to occur about 10 minutes to an hour from

the theoretical failure. However, according to Lie, a definite standard on this type of

failure is not found in any code and the actual instantaneous failure is still arbitrarily

decided by the engineers concerned. Hence this mode of failure cannot be

considered for any program until clearly specified in the code. However if this mode

of failure is to be used as the failure criterion as most of the case in experimental

tests, then all the measured fire-resistance will show a higher value. This means that

the calculated fire resistance will indicate a conservative values which for practical

purposes mean that the calculated fire resistances lie on the safe side.

5.0 CONCLUSIONS

Based on the results of this study, the following conclusions can be drawn:

The mathematical model [1] employed in this study is capable of predicting

the fire resistance of protected steel columns, made of l-shape steel section insulated

with ceramic fibre with an accuracy that is adequate for practical purposes. The

results indicate that the model is conservative in its predictions.

48


The model will enable the expansion of data on the fire resistance of ceramic

protected steel columns which at present predominantly consists of data for concrete

columns.

By usmg the mathematical model, the fire resistance of protected steel

columns can be evaluated for any value of the significant parameters such as load,

column-section dimensions, and thickness of insulation of ceramic fibre without the

necessity of testing.

The model can also be used for the calculation of the fire resistance of

columns made with I-shaped steel section insulated with material other than those

investigated in this study - for examples cementitious or board that were not tested if

the relevant material properties are known.

6.0 ACKNOWLEDGMENTS

The test was carried out at the National Fire Laboratory of the Institute for Research

in Construction, National Research Council of Canada. The author would like to

thank all the staff of NRCC for their assistance with the experiments. Special

mention should be given to John Latour and Patrice for their commitment m

providing the author with the help while building the specimens and testing them.

49

Jurna/ Mekanikal, Ji/id II. /996

REFERENCES

1. Ghani, B. A. et. al, Heat Transfer and Strength Analysis of Column at Extreme

Temperature, University Technology of Malaysia, 199.6.

2. El-Shayeb, Mohamed, Fire-Resistance of Concrete-Filled and Reinforced

Concrete Columns, PhD. Thesis, University of New Hampshire, USA, May

1986.

3. Lie, T. T. ,Temperature of Protected Steel in Fire, Behaviour of Structural Steel

in Fire, Ministry of Technology and Fire Offices, Committee Joint Fire

Research Organisation Symposium No.2, H. M. S. 0., London, 1968.

4. Lie, T. T. Feasibility of Determining the Equilibrium Moisture Condition in Fire

ResistanceTest Specimens by Measuring their Electrical-resistance, Building

Research Note No. 75, Division of Building Research, NRC, Ottawa, 1971.

5. Dusinberre, G. M. Heat Transfer Calculations by Finite Differences,

International Textbook Company, Scranton, Pennsylvania, 1961.

6. Harmathy, T. Z. A Treatise on Theoretical Fire Endurance Rating, American

Society for Testing Materials, Special Technical Publication No. 301, 1961, pp.

10-40.

7. Harmathy T. Z. and Lie T. T., Experimental Verification of the Rule of

Moisture Moment, Fire Technology, Vol. 7, 1964 p. 17.

8. Bibliography Bardell, Kathleen. Spray-Applied Fire Resistive Coatings for Steel

Building Columns, Fire Resistive Coatings: The Need For Standards, ASTM

STP 826 Morris Lieff and F.M. Stumpf, eds., American Society for Testing and

Materials, 1983,40-55.

50

lurnal Mekanikal, Jilid ll, 1996

9. Standard Methods of Mire Tests of Building Construction and Materials, ASTM

Designation E119-69, 1969 Book of ASTM Standards, Part 14, pp. 436-452.

10. Brit, Iron Steel Res. Assoc., Physical Constants of Some Commercial Steels at

Elevated Temperature, Butterworths Sci. Publ., London, 1953.

11. Fujii, S. The Theoretical Calculation of Temperature-rise of Thermally Protected

Steel Column Exposed to the Fire, Building Research Institute Occasional

Report No. 10, Tokyo, 1963.

12. Emmons H. W., The Numerical Solution of Heat Conduction Problems,

Transactions of the American Society of Mechanical Engineers, Vol. 65, 1943,

pp.607-615.

13. Thrinks W. and Mawhinney M. W., Industrial Furnaces, John Wiley and Sons,

Inc., New York, 1986

14. Law, M., Structural Fire Protection in the Process Industry Building, Vol. 216,

No. 29, 1969, pp. 86-90.

15. Rains W.A., Evaluation on Existing Fire Protection Materials, Phase I Report,

Presented to the American Iron and steel Institute Fire Technology

Subcommittee, 1973.

16. Stumpf Frank M., Spray-Applied Fibrous Materials and Fire Resistive Coatings,

Presented to the ASTM, 1984.

51

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