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

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capabilities has been limited to the thermal analyses of steel beam cross sections. The thermal properties change with temperature as programmed into the computer package, and these vary as recommended by EC3. Refer to Section 1.6.2 for these equations. The analysing process of a cross section of a steel beam, through SAFIR is as follows: Wizard/Pre-processor In this computer package the details of the cross-section of the beam are entered in a graphic layout, and the properties of the insulation, if appropriate, are added. The required time step, and the type of output is requested. Other options to add or edit at this stage are the initial temperature; integration and calculation parameters and accuracy and re-numbering of equations time discretisation. Output can be either in the form of temperatures of the nodes, or the average temperature of the elements at each time step. The pre-processor therefore, creates *.str and *.dat files which the SAFIR programme requires for an analysis of a cross section of an element. The *.str files contains information regarding the geometry of the cross section, the placement of the nodes and elements and the exposed edges to the fire. The *.dat files contain the calculation information such as the integration accuracy and length of the time step. Types of cross sections that can be analysed include unprotected members; protected members with up to three types of insulation, and whether the beam supports a concrete slab. Changes to the number of elements being analysed can be made to increase or decrease the accuracy. The user also defines the type of fire that the element is subjected to and which faces of the element are exposed to the fire. The wizard programme was developed by G. Ionica and Y. Vanderseipen in 1998, under the supervision of Dr J-M. Franssen at the University of Liege. The Preprocessor developed by John Mason has more functions including options for box 27
protection, and for user defined fires. The alternative pre-processor by Mason (2000) has been the primary tool in setting up files for SAFIR to analyse in this project. SAFIR The SAFIR programme can calculate a thermal analysis of a cross section, which is what it has been required to do in this project. If a more complex structure, rather than just a cross section had been analysed, then SAFIR would break the structure into smaller sub-structures and perform temperature calculations for each sub-structure, performing first a 2-D SOLID element analysis and using this information to give a 3- D result. Therefore with a two dimensional model, all that is required by SAFIR is to perform heat flow calculations around the element cross section. The SAFIR programme creates *.out, *.log and either *.tem or *.tnd output files. *.out files contain all information regarding the structure, including what is found in the *.str and *.dat files, together with the temperatures of the nodes at each time step and the energy received by the cross section element. *.tem and *.tnd files are files with the temperatures of the elements or nodes recorded at each time step respectively. Diamond The Diamond programme is a post processor of SAFIR, that reads the output files, *.out, generated by SAFIR and displays the results of the analysis in a graphical and pictorial form. Diamond can generate a time temperature curve for each node because the temperature of each node is evaluated at each time step and included in the *.out files. This means that the temperature rise of different nodes across the cross-section can be observed with time. At each time step calculated by SAFIR, the temperature over the cross section of the element can be shown either by block colours or with contour lines and the user can choose the range of temperature values. 2.3.2 Firecalc: Firecalc is a software package that incorporates 24 different fire analysis tools to determine the behaviour of fires and fire systems. Some of the functions include the 28
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: spreadsheet method very closely, wi
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
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
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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
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
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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
Page 120 and 121:
1000 Temperature ( o C) 800 600 400
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Thermal conductivity, k i = 0.19 W/
Page 124 and 125:
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
Page 152 and 153:
It is therefore recommended that th
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These methods may be used to provid
Page 156:
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
Page 163 and 164:
EC3, 1995. Eurocode 3: Design of St
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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
Page 176:
APPENDIX C - FIRECALC Below in Figu
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