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

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constant specific heat being used in the spreadsheet method, but since the difference is small in both cases; the simple method of keeping the specific heat constant appears to be more reasonable. Using a specific heat that varies with temperature in the spreadsheet method shows how closely the spreadsheet method results match those that are given by the finite element computer programmes. Because the spreadsheet method is much easier to access and work compared with the computer programmes, for thermal calculations of simply supported beams with four sided fire exposure. this method is the best to use. 5.3.2 Comparison with the ECCS Formula: Comparisons with the formulas recommended by ECCS have been plotted against the results from the SAFIR simulations and the simplified spreadsheet results in Figure 5.7 a-c. Equation 5.1, by ECCS used in Section 5.2.3, is used in its original form without the modification for heavy insulation, since the properties of Mandolite satisfy the conditions of equation 2.4, as shown in Section 0. Figure 5.7 a-c shows the accuracy of the ECCS formula when applied to steel sections with light protection. The ECCS formula is compared to results from the spreadsheet method with the light insulation simplification, but with a constant value for the specific heat of steel. Results from SAFIR are also included to compare the formula with ‘real’ behaviour of steel under the conditions of the analysis. When light protection is used as in Figure 5.5 a-c, the unmodified spreadsheet method has slightly lower temperatures than the simplified version. The SAFIR results are lower than the results from both spreadsheet methods due to the changing thermal properties installed in the programme. The ECCS equation has the best correlation with the spreadsheet 2 curve, which neglects the heat capacity of the insulation term. The section factor for the lightest beam, 180UB16.1, is out of the recommended range of beam sizes for the ECCS equation, but the formula predicts the temperatures equally well for this beam as with the other beam sizes. 97
Temperature ( o C) 1200 1000 800 600 400 200 ECCS Spreadsheet 2 SAFIR 0 0 50 100 150 200 Time (min) Spreadsheet 2 SAFIR ECCS 1000 Temperature ( o C) 800 600 400 200 0 0 50 100 150 200 Time (min) Spreadsheet 2 SAFIR ECCS 1000 Temperature ( o C) 800 600 400 200 0 0 50 100 150 200 Time (min) Spreadsheet 2 SAFIR ECCS Figure 5.7 a-c: Comparison between the results from the two spreadsheet methods, SAFIR and the ECCS recommended formula for steel with light insulation protection. From top to bottom: a. 180 UB 16, b. 310 UB 40.4 and c.530 UB 82.0 98
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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
Page 21 and 22:
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
Page 61 and 62: = H p A (m -1 ) 7.85 The cons
Page 63 and 64: Connections: NZS 3404 requires that
Page 66 and 67: 4 CALCULATION OF STEEL TEMPERATURES
Page 68 and 69: 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 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 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
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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
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APPENDIX C - FIRECALC Below in Figu
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