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

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6.2.4 Results for protected steel: The insulative protection used in this section is Fendolite and is also used in Section 5.2 and 5.5. The properties of this protection are as follows: Properties of spray on protection: Fendolite by Firepro Specific heat, c i = 1100 J/kg K Thermal conductivity, k i = 0.19 W/m K Density, ρ = 775 kg/m 3 Thickness, d i = 0.02 m 1400 1200 Temperature ( o C) 1000 800 600 400 200 0 0 50 100 150 200 Time (min) Spreadsheet Fire temperature SAFIR 1000 Temperature ( o C) 800 600 400 200 0 0 50 100 150 200 Time (min) Spreadsheet SAFIR Figures 6.2 a-b: Comparison between the results from SAFIR and the spreadsheet method for protected steel exposed to a Eurocode parametric fire. From top a. with constant specific heat in spreadsheet method, b. with varying specific heat with spreadsheet method 121
Protected steel exposed to the Eurocode parametric fire gives similar results to the results found from the comparisons with beams exposed to the standard ISO 834 fire. The results from the spreadsheet give higher temperatures than the results from the SAFIR programme as with the results with the ISO fire. The curve with results from the spreadsheet method allows for the heat capacity of the insulation due to the properties of the insulation being classed ‘heavy’. This Eurocode parametric fire has a ventilation factor of 0.08, a fuel load of 800 MJ/m 2 , and a thermal inertia of the wall linings of 1160 Ws 1/2 /m 2 K and is the ‘middle’ fire of those used in this report. The beam is the medium weight beam used throughout this report and sized as BHP 310 UB 40.4. Figures 6.2 a, the spreadsheet curve and SAFIR curve follow the same path until the temperature reaches about 650 °C, at a time of about 45 minutes. The spreadsheet then gives lower temperatures than the SAFIR programme. The lower temperatures from SAFIR after the steel reaches a temperature of 650 °C is due to the higher specific heat of steel which is taken into account by SAFIR but not in the spreadsheet method. The slower decrease in temperature in the decay stage of the fire is due to the same effect. The temperature difference between the two methods is more pronounced in protected steel than unprotected steel due to the time period that the steel is in the 650 – 800 °C temperature range. Since the steel is heating up at a slower rate with protected steel than with unprotected steel, the time that the steel is in this temperature range is longer and the results from the spreadsheet method deviate further from the SAFIR temperatures in these situations. The results from the spreadsheet turn out to be quite conservative because it estimates higher temperatures due to this effect and the maximum temperature reached in the beam from the spreadsheet method is 901 °C while the maximum temperature found from SAFIR is 800 °C. The difference of slightly more than 100 °C, means the spreadsheet has a maximum temperature of 12.5 % more than that found from using the SAFIR simulation. 122
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Fire Design of Steel Members K R Le
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ABSTRACT: The New Zealand Steel Cod
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TABLE OF CONTENTS: ABSTRACT:.......
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5.4 RESULTS FOR FOUR SIDED EXPOSURE
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LIST OF FIGURES: FIGURE 1.1: VARIAT
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FIGURE 5.11: TEMPERATURE CONTOUR LI
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designed with confidence. Full scal
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eams and struts when subjected to a
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Gilvery and Dexter, (1997), prepare
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with conditions specified to ensure
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1.6 BACKGROUND INFORMATION: 1.6.1 F
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experienced in fire situations, but
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The thermal conductivity is not imp
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[ The heated perimeter of the steel
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The advantages of board systems are
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The values for the thermal properti
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insulation has on the rise of the s
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( T − T ) k H p f s ∆t ∆T
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spreadsheet method very closely, wi
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protection, and for user defined fi
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This equation originates from the y
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1400 1200 1000 800 600 400 200 0 0.
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time. The value of the wall lining
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The Eurocode does not define a meth
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f f y y ( T ) (20) = 1.0 0 < T < 21
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temperature is chosen because it is
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The variation of yield stress data
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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
Page 86 and 87: average temperature of the beam, be
Page 88 and 89: Temperature ( o C) 1400 1200 1000 8
Page 90 and 91: significantly decreased from a cool
Page 92 and 93: Since both programmes use the same
Page 94 and 95: Therefore, the ECCS equations provi
Page 96 and 97: 5 CALCULATION OF STEEL TEMPERATURES
Page 98 and 99: calculations made by the spreadshee
Page 100 and 101: susceptible to heating, heat up mor
Page 102 and 103: Figure 5.3 a-c show the results fro
Page 104 and 105: 7850*600*10500 > 2*775*1100*(1869*2
Page 106 and 107: As can be seen from Figure 5.4 a-c,
Page 108 and 109: 310 UB 40.4 beam H p /A = 241 m -1
Page 110 and 111: The SAFIR results fit between the t
Page 112 and 113: constant specific heat being used i
Page 114 and 115: From Figure 5.7 a-c, it appears tha
Page 116 and 117: 800 Temperature ( o C) 600 400 200
Page 118 and 119: To examine the limits of the thickn
Page 122 and 123: Thermal conductivity, k i = 0.19 W/
Page 126 and 127: the slab except to reduce the secti
Page 128 and 129: Figure 5.14 shows the correlation b
Page 130 and 131: 5.8 CONCLUSIONS: The thermal behavi
Page 132 and 133: 6 COMPARISON OF METHODS USING OTHER
Page 134 and 135: Temperature ( o C) 1200 1000 800 60
Page 138 and 139: Figures 6.2 b shows the comparison
Page 140 and 141: Figure 6.3 a shows that the average
Page 142 and 143: The fire that the test beams were e
Page 144 and 145: 7 ADDITIONAL MATERIAL IN EUROCODE 3
Page 146 and 147: For thermal analysis in Eurocode 3,
Page 148 and 149: To determine the performance of a s
Page 150 and 151: The plastic neutral axis is located
Page 152 and 153: It is therefore recommended that th
Page 154 and 155: These methods may be used to provid
Page 156: Eurocode has a large annex with gui
Page 159 and 160: 8.3 CHANGES TO NZS 3404: The follow
Page 161 and 162: H v height of the ventilation (m) I
Page 163 and 164: EC3, 1995. Eurocode 3: Design of St
Page 165 and 166: Temperature Conditions. National Re
Page 168 and 169: APPENDIX A - SPREADSHEET METHOD: Be
Page 170 and 171: APPENDIX B - SAFIR: In Figure B.2 i
Page 172 and 173: *.str file developed by the pre pro
Page 174 and 175: 22 FISO 23 FISO FISO 24 FISO FISO 2
Page 176: APPENDIX C - FIRECALC Below in Figu
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