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

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1000 Temperature ( o C) 800 600 400 200 0 0 50 100 150 200 Time (min) SAFIR Spreadsheet ECCS 1000 Temperature ( o C) 800 600 400 200 0 0 50 100 150 200 250 Time (min) SAFIR Spreadsheet ECCS 1000 Temperature ( o C) 800 600 400 200 0 0 50 100 150 200 250 300 Time (min) SAFIR Spreadsheet ECCS Figure 5.10 a-c: Comparison between results from the spreadsheet method with the results from SAFIR and with the ECCS equations for protected steel members with heavy thick protection. From top to bottom: a. 180 UB 16, b. 310 UB 40.4 and c.530 UB 82.0 105
From Figure 5.10 a-c, the ECCS equations give good results again with the average steel temperatures found from the results of SAFIR simulations and spreadsheet analyses. The upper temperature limitation again can be increased to 800 °C, and linear interpolation below 400 °C would give accurate results. The time and beam size limitations do not appear to be relevant in this analyses which supports the conclusions stated in Sections 5.2.3 and 5.3.2. The average SAFIR temperature is always slightly cooler than the temperature from the spreadsheet calculations as is also seen in Figure 5.9. The effect of the thicker protection is to distribute the energy conducted to the steel more evenly and at a slower rate. This means that conduction through the steel section more actively reduces the variation of temperature across the cross section. In the spreadsheet method conduction is not considered because the one dimensional heat flow model that the formulas are based on give a uniform thickness and energy flow to the steel. 5.6 RESULTS FOR THREE SIDED EXPOSURE WITH HEAVY PROTECTION: Protected beams with three sided exposure usually occurs when a concrete slab is being supported by a steel beam, and the other three faces are protected with insulation. In this section this is the only case considered, as the cases where insulation is applied to the top face and three sided exposure still occurs is unlikely. This approach gives lower temperatures than if insulation was applied to the top face, but as seen in Section 4.3.1 and Figure 4.10, the maximum temperature of the steel section is unaffected by the introduction of a concrete slab rather than insulation to the top face. For this reason this simplification in comparing methods has been taken. The properties of the insulation applied to the steel section are those of Fendolite by Firepro Safety Ltd, also used in Section 5.2, with constant values taken as below: Specific heat, c i = 1100 J/kg K 106
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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
Page 70 and 71: Figure 4.2 shows the variation of t
Page 72 and 73: Minimum temperatures Maximum temper
Page 74 and 75: For all three sizes of beam, the sp
Page 76 and 77: Temperature ( o C) 1200 1000 800 60
Page 78 and 79: The ECCS equation has a time period
Page 80 and 81: 4.3.1 Results from simulations with
Page 82 and 83: From Figure 4.5 a-c, the formula ra
Page 86 and 87: average temperature of the beam, be
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 124 and 125: 1000 Temperature ( o C) 800 600 400
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 136 and 137: 6.2.4 Results for protected steel:
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
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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
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APPENDIX C - FIRECALC Below in Figu
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