FIRE DESIGN OF STEEL MEMBERS - Civil and Natural Resources ...

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TABLE OF CONTENTS: ABSTRACT:.............................................................................................................................. I ACKNOWLEDGMENTS: .................................................................................................... III LIST OF FIGURES: ...............................................................................................................IX 1 INTRODUCTION:...........................................................................................................1 1.1 OBJECTIVES:...................................................................................................................1 1.2 PREVIOUS STUDIES:........................................................................................................1 1.3 SCOPE OF THIS REPORT: ..................................................................................................6 1.4 NZS 3404:PART 1:1997 SECTION 11:............................................................................7 1.5 OTHER STEEL CODES .....................................................................................................8 1.5.1 BS 5950:Part 8:1990.............................................................................................8 1.5.2 AS 4100:1990 ........................................................................................................9 1.5.3 ENV 1993-1-2........................................................................................................9 1.6 BACKGROUND INFORMATION:......................................................................................10 1.6.1 Forms of Heat Transfer:......................................................................................10 1.6.2 Thermal Properties of Steel:................................................................................11 1.6.3 Section Factor, H p /A:...........................................................................................15 1.6.4 Methods of steel protection: ................................................................................17 2 FIRES AND THERMAL ANALYSIS COMPUTER MODELS: ..............................19 2.1 SPREADSHEET METHOD: ..............................................................................................19 2.1.1 Introduction:........................................................................................................19 2.1.2 Unprotected Steel: ...............................................................................................20 2.1.3 Protected steel:....................................................................................................21 2.2 ALTERNATIVE FORMULATIONS OF THE SPREADSHEET METHOD: ................................23 2.3 THERMAL ANALYSIS PROGRAMMES:...........................................................................26 2.3.1 SAFIR: .................................................................................................................26 2.3.2 Firecalc: ..............................................................................................................28 2.4 FIRE CURVES: ...............................................................................................................30 2.4.1 Standard Fire – ISO 834: ....................................................................................30 2.4.2 Eurocode Parametric fire:...................................................................................31 3 FIRE SECTION OF THE STEEL CODES:................................................................35 3.1 NZS3404/AS4100:.......................................................................................................35 v
3.1.1 Determination of Period of Structural Adequacy (PSA): ....................................35 3.1.2 Variation of Mechanical Properties of Steel with Temperature:.........................36 3.1.3 Determination of Limiting Steel Temperature:....................................................42 3.1.4 Temperature rise of unprotected steel: ................................................................43 3.1.5 Temperature rise of protected steel: ....................................................................44 3.1.6 Determination of PSA from a single test: ............................................................46 3.1.7 Special Considerations:.......................................................................................47 4 CALCULATION OF STEEL TEMPERATURES FOR UNPROTECTED STEEL – ISO FIRE: ................................................................................................................................51 4.1 INTRODUCTION: ............................................................................................................51 4.1.1 Assumptions .........................................................................................................52 4.1.2 Analysis Between Methods of Temperature Evaluation: .....................................53 4.2 RESULTS FOR FOUR SIDED EXPOSURE: ........................................................................54 Results from a simulation with the SAFIR programme: ...................................................54 4.2.2 Unprotected steel beam with four sided exposure:..............................................57 4.2.3 Comparison with NZS 3404 and ECCS formulas for four sided exposure:.........59 4.3 RESULTS FOR THREE SIDED EXPOSURE:.......................................................................63 4.3.1 Results from simulations with the SAFIR programme:........................................65 4.3.2 Unprotected steel beam with three sided exposure: ............................................68 4.3.3 Comparison with NZS 3404 and ECCS formulas for three sided exposure: .......71 4.4 COMPARISONS WITH OTHER FINITE ELEMENT PROGRAMMES:....................................75 4.4.1 Comparison of FIRES-T2 with SAFIR:................................................................75 4.4.2 Comparison with Firecalc:..................................................................................77 4.5 CONCLUSIONS:..............................................................................................................78 5 CALCULATION OF STEEL TEMPERATURES FOR PROTECTED STEEL – ISO FIRE: ................................................................................................................................81 5.1 INTRODUCTION: ............................................................................................................81 5.1.1 Assumptions:........................................................................................................81 5.2 RESULTS FOR FOUR SIDED EXPOSURE WITH HEAVY PROTECTION:.............................82 5.2.1 Results from a simulation with the SAFIR programme: ......................................83 5.2.2 Heavily Protected Beam with Four Sided Exposure: ..........................................85 5.2.3 Comparison with the ECCS equation:.................................................................88 5.3 RESULTS FOR FOUR SIDED EXPOSURE WITH LIGHT PROTECTION:................................91 5.3.1 Lightly Protected Beams with Four Sided Exposure:..........................................92 5.3.2 Comparison with the ECCS Formula:.................................................................97 vi
Page 1 and 2: Fire Design of Steel Members K R Le
Page 4: ABSTRACT: The New Zealand Steel Cod
Page 10 and 11: 5.4 RESULTS FOR FOUR SIDED EXPOSURE
Page 12 and 13: LIST OF FIGURES: FIGURE 1.1: VARIAT
Page 14: FIGURE 5.11: TEMPERATURE CONTOUR LI
Page 17 and 18: designed with confidence. Full scal
Page 19 and 20: eams and struts when subjected to a
Page 21 and 22: Gilvery and Dexter, (1997), prepare
Page 23 and 24: with conditions specified to ensure
Page 25 and 26: 1.6 BACKGROUND INFORMATION: 1.6.1 F
Page 27 and 28: experienced in fire situations, but
Page 29 and 30: The thermal conductivity is not imp
Page 31 and 32: [ The heated perimeter of the steel
Page 33 and 34: The advantages of board systems are
Page 35 and 36: The values for the thermal properti
Page 37 and 38: insulation has on the rise of the s
Page 39 and 40: ( T − T ) k H p f s ∆t ∆T
Page 41 and 42: spreadsheet method very closely, wi
Page 43 and 44: protection, and for user defined fi
Page 45 and 46: This equation originates from the y
Page 47 and 48: 1400 1200 1000 800 600 400 200 0 0.
Page 49 and 50: time. The value of the wall lining
Page 51 and 52: The Eurocode does not define a meth
Page 53 and 54: f f y y ( T ) (20) = 1.0 0 < T < 21
Page 55 and 56: temperature is chosen because it is
Page 57 and 58:
The variation of yield stress data
Page 59 and 60:
15 m -1 < H p /A < 275 m -1 in NZS
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= H p A (m -1 ) 7.85 The cons
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Connections: NZS 3404 requires that
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4 CALCULATION OF STEEL TEMPERATURES
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4.1.2 Analysis Between Methods of T
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Figure 4.2 shows the variation of t
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Minimum temperatures Maximum temper
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For all three sizes of beam, the sp
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Temperature ( o C) 1200 1000 800 60
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The ECCS equation has a time period
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4.3.1 Results from simulations with
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From Figure 4.5 a-c, the formula ra
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Temperature ( o C) 1000 800 600 400
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average temperature of the beam, be
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Temperature ( o C) 1400 1200 1000 8
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significantly decreased from a cool
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Since both programmes use the same
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Therefore, the ECCS equations provi
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5 CALCULATION OF STEEL TEMPERATURES
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calculations made by the spreadshee
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susceptible to heating, heat up mor
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Figure 5.3 a-c show the results fro
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7850*600*10500 > 2*775*1100*(1869*2
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As can be seen from Figure 5.4 a-c,
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310 UB 40.4 beam H p /A = 241 m -1
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The SAFIR results fit between the t
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constant specific heat being used i
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From Figure 5.7 a-c, it appears tha
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800 Temperature ( o C) 600 400 200
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To examine the limits of the thickn
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1000 Temperature ( o C) 800 600 400
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Thermal conductivity, k i = 0.19 W/
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1000 Temperature ( o C) 800 600 400
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the slab except to reduce the secti
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Figure 5.14 shows the correlation b
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5.8 CONCLUSIONS: The thermal behavi
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6 COMPARISON OF METHODS USING OTHER
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Temperature ( o C) 1200 1000 800 60
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6.2.4 Results for protected steel:
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Figures 6.2 b shows the comparison
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Figure 6.3 a shows that the average
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The fire that the test beams were e
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7 ADDITIONAL MATERIAL IN EUROCODE 3
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For thermal analysis in Eurocode 3,
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To determine the performance of a s
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The plastic neutral axis is located
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It is therefore recommended that th
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These methods may be used to provid
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Eurocode has a large annex with gui
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8.3 CHANGES TO NZS 3404: The follow
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H v height of the ventilation (m) I
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EC3, 1995. Eurocode 3: Design of St
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Temperature Conditions. National Re
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APPENDIX A - SPREADSHEET METHOD: Be
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APPENDIX B - SAFIR: In Figure B.2 i
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*.str file developed by the pre pro
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22 FISO 23 FISO FISO 24 FISO FISO 2
Page 176:
APPENDIX C - FIRECALC Below in Figu
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