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

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t d 0.00013et = A v H v A t where e t is the fuel load in the compartment (MJ/m 2 total surface area) 2.14 After the period of heating, t d , has been completed the fire cools down linearly. Buchanan (1999), modified the original Eurocode method of decay because there appeared to be confusion between fictitious time and real time, and the Eurocode method gave excessive cooling rates with larger openings. Wickstrom suggested that the decay rates apply to real time, with cooling magnitudes of 625 °C for fires of duration of less than half an hour, decreasing to 250 °C for fires of greater than two hours duration, (Buchanan 1999) For the purpose of this project the decay rate used will be as suggested by Buchanan: dT F kρc v = 625 p dt 0.04 1160 This is also the form of the decay rate equation that is used in the pre-processor developed by John Mason used in later sections of this report. 2.15 As seen in equations 2.7 a-b, the growth rate of the Eurocode parametric fire is independent of the fuel load in the compartment, which intuitively appears incorrect that the fuel load does not affect the temperature of the fire. Since the Eurocode Parametric fires are ventilation controlled, however, the fuel load does not affect the temperature rise, as the temperature is more dependent on the ventilation available to the fire. In the early stages of the fire, however, when the fire is more likely to be fuel controlled, the amount of fuel would affect the fire temperatures. Since for establishing the fire resistance of structural members the fire has a significant duration, this assumption of ventilation controlled fires is not inappropriate. Since the Eurocode fire is a function of three variables, namely ventilation factor, fuel load and wall lining properties, there are a large number of possible fires to be formed when different values are used for each variable. To reduce the number of fires studied here, a standard case has been chosen, from which one variable is changed at a 33
time. The value of the wall lining properties factor √(kρc p ) is kept at a constant value of 1160 during all tests. For the standard case, the ventilation factor is 0.08 and the fuel load is 800 MJ/m 2 of total surface area. The ventilation factor then varies to 0.04 and 0.12 and the fuel load varies to 400 and 1200 MJ/m 2 of total surface area. Varying these dependants singly results in 5 different fire curves as shown in Figure 2.5. 34
Page 1 and 2: Fire Design of Steel Members K R Le
Page 4: ABSTRACT: The New Zealand Steel Cod
Page 8 and 9: TABLE OF CONTENTS: ABSTRACT:.......
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: 1400 1200 1000 800 600 400 200 0 0.
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
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 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 120 and 121:
1000 Temperature ( o C) 800 600 400
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 134 and 135:
Temperature ( o C) 1200 1000 800 60
Page 136 and 137:
6.2.4 Results for protected steel:
Page 138 and 139:
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
Page 146 and 147:
For thermal analysis in Eurocode 3,
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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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