AP04-Bittnar2.vp 1 Introduction The BRE’s Cardington Laboratory is a unique facility for advancement of the understanding of whole-building perfor- mance, see [1]. This facility is located at Cardington, Bedford- shire, UK, and consists of a former airship hangar with di- mensions 48 m×65 m×250 m. The Cardington Laboratory comprises three experimental buildings: a six storey timber structure, a seven storey concrete structure, and an eight storey steel structure. The steel test structure was built in 1993. It is a steel framed structure using composite concrete slabs supported by steel decking in composite action with the steel beams. It has eight storeys (33 m) and is five bays wide (5×9 m � 45 m) by three bays deep (6 � 9 � 6 � 21 m) in plan. The structure was built as non-sway with a central lift shaft and two end staircases providing the necessary resistance to lateral wind loads. The main steel frame was designed for gravity loads, the connections consisting of flexible end plates for beam-to-column connections and fin plates for beam-to- -beam connections, designed to transmit vertical shear loads. The building simulates a real commercial office in the Bed- ford area, and all the elements were verified according to British Standards and checked for compliance with the provi- sions of the Structural Eurocodes. The building was designed for a dead load of 3.65 kN m�2 and an imposed load of 3.5 kN m�2. The floor construction consists of a steel deck and a light-weight in-situ concrete composite floor, incorpo- rating an anti-crack mesh of 142 mm2 m�1 in both directions, see [2]. The floor slab has an overall depth of 130 mm and the steel decking has a trough depth of 60 mm. Seven large-scale fire tests at various positions within the experimental building were conducted, see [3], and there is still a place for two more tests. The main aim of these compartment fire tests was to assess the behaviour of structural elements with real restraint in a natural fire. The structural integrity fire test (large test No.7) was carried out in a centrally located compartment of the building, enclosing a plan area of 11 m by 7 m on the 4th floor [4]. The preparatory works took four months. The fire com- partment was bounded with walls made of three layers of plas- terboard (15 mm + 12.5 mm + 15 mm) with thermal con- ductivity (0.19–0.24) W m�1K�1. In the external wall the plas- terboard was fixed to a 0.9 m high brick wall. The opening 1.27 m in hight and 8.7 m in length simulated an open window to ventilate the compartment and allow for observa- tion of the element behaviour. The ventilation condition was chosen to result in a fire of the required severity in terms of maximum temperature and overall duration. The steel structure exposed to fire consists of two se- condary beams (section 305×165×40UB, steel S275 mea- sured fy � 303 MPa; fu � 469 MPa), an edge beam (section 356×171×51UB), primary beams (section 336×171×51UB, steel S350 measured fy � 396 MPa; fu � 544 MPa) and col- umns, internal section 305×305×198UC and external 305×305×137UC, steel S350. The joints were a cruciform arrangement of a single column with three or four beams con- nected to the column flange and web by the header plate con- nections, steel S275. The beam to beam connections were cre- ated by fin plates, steel S275. The composite behaviour was achieved by a concrete slab (lightweight concrete LW 35/38; experimentally by a Schmidt hammer 39.4 MPa) over beams cast on shear studs (�19–95; fu � 350 MPa). The geometry and material properties of the measured section are summa- rized in Table A1, see [2, 5]. The mechanical load was simulated using sandbags, 1100 kg of each, applied over an area of 18 m by 10.5 m on the 5th floor. The sand bags represent the mechanical load- ings; 100 % of permanent actions, 100 % of variable perma- nent actions and 56 % of live actions. The mechanical load was designed to reach the collapse of the floor, based on analytical and FE simulations. Wooden cribs with 14 % mois- ture content provided the fire load of 40 kg/m2 of the floor area, see Fig. 1a,b. The columns, external joints and connected beam (about 1.0 m from the joints) were fire protected to prevent global structural instability. The material protection used was 20 mm of Cafco300 vermiculite-cement spray, based on vermiculite and gypsum, see Table A2 and Fig. 1c, d. It was applied as a single package factory controlled premix, with a thermal conductivity of 0.078 W m�1K�1. © Czech Technical University Publishing House http://ctn.cvut.cz/ap/ 131 Acta Polytechnica Vol. 44 No.5–6/2004 Temperature of Steel Columns under Natural Fire F. Wald, P. Studecká, L. Kroupa Current fire design models for time-temperature development within structural elements as well as for structural behaviour are based on isolated member tests subjected to standard fire regimes, which serve as a reference heating, but do not model natural fire. Only tests on a real structure under a natural fire can evaluate future models of the temperature developments in a fire compartment, of the transfer of heat into the structure and of the overall structural behaviour under fire. To study overall structural behaviour, a research project was conducted on an eight storey steel frame building at the Cardington Building Research Establishment laboratory on January 16, 2003. A fire compartment 11×7 m was prepared on the fourth floor. A fire load of 40 kg/m2 was applied with 100 % permanent mechanical load and 65 % of imposed load. The paper summarises the experimental programme and shows the temperature development of the gas in the fire compartment and of the fire protected columns bearing the unprotected floors. Keywords: steel structures, fire design, fire test, compartment temperature, protected steel, natural fire. The paper describes the temperature development in the fire protected columns. The temperatures predicted ana- lytically and by 2D FEM simulation are compared to the measured values. 132 © Czech Technical University Publishing House http://ctn.cvut.cz/ap/ Acta Polytechnica Vol. 44 No.5–6/2004 a) b) c) d) Fig. 1: a) Fire load in compartment; b) fire load around column D2; c) protection of internal column D2 (after test), d) protection of ex- ternal column (after test) D E N G525 G526 G527 G528 G529 G530 G531 G532 1 2 G533 G534 G535 G536 0,80,8 2,25 2,25 2,252,25 0,5625 1,625 1,625 1,625 0,5625 Internal wall of the fire compartment North view 50 C415 A - A´ D2 major axis B - B´ D2 minor axis 200 C416 C417 50100 20 20 C418, C415, C419, C420 C418, C419, C420 a) b) Window of the fire compartment Fire protected part Fire protected part G521 G522 G523 G524 1,27 x 8,70 m C416, C417 PLAN 4th floor A - A´ B - B´ Fig. 2: a) Location of thermocouples in a compartment 300 mm below the ceiling; b) thermocouples on the beam and column end round the connection 2 Instrumentation The instrumentation used included thermocouples, strain gauges and displacement transducers. A total of 133 thermo- couples monitored the temperature of the connections and beams within the compartment, the temperature distribution through the slab and the atmospheric temperature within the compartment, see Fig. 2a. An additional 14 thermocouples measured the temperature of the protected columns, see Fig. 5. Two different types of gauge were used, high tempera- ture and ambient temperature, to measure the strain in the elements. In the exposed and unprotected elements (fin plate and end plate - minor axis) nine high temperature strain gauges were used. In the protected columns and on the slab a total of 47 ambient strain gauges were installed. 25 vertical displacement transducers were attached along the 5th floor to measure the deformation of the concrete slab. An additional 12 transducers were used to measure the horizontal move- ment of the columns and the slab. Ten video cameras and two thermo-imaging cameras recorded the fire and smoke devel- opment, the deformations and the temperature distribution, see [5]. 3 Fire development The quantity of thermal load and the dimensions of the opening on the facade wall were designed to achieve a repre- sentative fire in the office building. The openings allowed the fire to develop without a flashover managed by combustible timber sticks, see [4]. The temperature grew to reach the pla- teau of the time temperature curve in about 18 minutes, with a peak at 54 min., after which cooling began, see Fig. 3. The maximum recorded compartment temperature near the wall (2 250 mm from D2) was 1107.8 °C after 54 minutes. The predicted value was 1078 °C in 53 min, see [5]. During heat- ing the temperature was distributed regularly, see Fig. 4. The measured differences of gas temperature decreased during cooling from 200 °C to 20 °C in 120 min. The measured © Czech Technical University Publishing House http://ctn.cvut.cz/ap/ 133 Acta Polytechnica Vol. 44 No.5–6/2004 0 200 400 600 800 1000 1200 0 15 30 45 60 75 90 105 120 135 150 Time, min Temperature, °C Back in fire compartment Prediction, EN 1991-1-2, Annex B [10] In front of fire compartment Everage temperature 300 1562,5 562,5 Fire compartment (DE, 1-2) 1108 °C 1078 °C 3 * 1 625 53 min. G525 G525 G526 G528 G526 G528 predicted 54 min. recorded Fig. 3: Comparison of the prediction of the gas temperature with the measured temperatures, for values see Table B1 Fig. 4: Isotherms in the compartment with thermocouples 300 mm under the ceiling, the input data are summarised in Table B1 maximum gas temperatures are summarised in tab. B1 in the time intervals. The average gas temperature is calculated from all sixteen thermocouples. 4 Column temperatures The temperatures in the columns in the fire compart- ment were measured at middle of the compartment’s height, 500 mm from the floor, and 500 mm below the ceiling at both flanges and at its web, and in the connections, see Figs. 2b and 5, Table B2. The columns were fire protected except the joint area, where the primary and secondary beams were con- nected. A selection of the temperatures recorded at column D1 and D2 is presented in Figs. 6 and 7, where they compared to the gas temperature, the beam mid-span temperature, the beam end temperature as well as the column end tempera- ture. The fire created a homogeneous gas temperature, and both columns were heated almost equally. The maximum re- 134 © Czech Technical University Publishing House http://ctn.cvut.cz/ap/ Acta Polytechnica Vol. 44 No.5–6/2004 C409, C412, C414 C429, C432, C434 C411 C431 C408, C410, C413 C417,C416,C415 C437,C436,C435 C408 C409 C429 C428 C412 C432, C431 C430 C413 C414 C434 C433 Column E2 C402, C405, C407 C422, C425, C427 C400 C424 C401,C403,C406 C421,C423,C426 C401,C402 C421,C422 C403,C405 C423, C425 C406,C407 C426, C427 Column D1 Column E1 500 500 1348 1348 UC 305 x 305 x 198 Colum D2 UC 305 x 305 x 137 UC 305 x 305 x 137 UC 305 x 305 x 137 C428, C430, C433 C410, C411 C420,C419,C418 C440,C439,C438 C424C404 Fig. 5: Location of thermocouples on columns/beams, on flanges 20 mm from edge, on web in centreline 0 200 400 600 800 1000 0 30 60 90 120 150 Secondary beam D2-E2; Temperature, °C Time, min. Gas temperature External column E1 TC525 TC488 midspan, lower flange at mid height TC421 N E2D2 E1D1 C488 C421 E2 C421 C421 E1 C428 C430 C433 500 500 1348 1348 C428 C430 C433 Internal column E2, 500 mm under slab, TC428 Internal column E2, at mid height, TC430 Internal column E2, 500 mm above floor, TC433 Fig. 6: Comparison of the measured temperature along the column length to the gas and connected beam temperature (column D2) and external column temperature (D1) 0 200 400 600 800 1000 0 30 60 90 120 150 Temperature, °C Time, min. Gas temperature External column D1, thermocouple C401 Secondary beam D2-E2; G525 midspan, lower flange, N E2D2 E1D1 C488 C401 Internal column D2, 500 mm under slab, C408 Internal column D2, at mid height, C410 Internal column D2, 500 mm above floor, C413 D2 C401 C401 D1 C408 C410 C413 500 500 1348 1348 C408 C410 C413 C488 Fig. 7: Comparison of the measured temperature along the column length with the gas and connected beam temperature (column E2) and external column temperature (E1) ported temperature in the insulated part of the middle col- umn was 426.0 C, which occurred after 106 minutes of fire. The values reached at the middle height of column and in the upper part of the column were similar. The gradient of the temperatures along the column changed in the course of time. The differences of the measured temperature cross sections were insignificant, see Table B2. The accurate and simple step-by-step calculation proce- dure is based on the principle that the heat entering the steel over the exposed surface area in a small time step � t (taken as 30 seconds maximum) is equal to the heat required to raise the temperature of the steel by �a,t (at time t) assuming that the steel section is a lumped mass at uniform temperature, so that � , ,�� �q F t c Va a t a t� �� � , (1) where �a is the unit mass of steel, ca,t is the temperature de- pendent specific heat of steel, V is the volume of the member per unit length, and ���q is the heat transfer at the surface, given by � ( ) ( ), , , ,�� � � � �q hc g t a t g t a t� � � �� � � � � � 4 4 , (2) where hc is the convective heat transfer coefficient, � is the Stefan-Bolzman constant (56.7 10�12 kW m�2 K�4), � is the resultant emissivity, and � � g t, is the increase of the ambient gas temperature during the time interval � t. Eqs (1) and (3) may be rearranged to give � �� � � � � �� � � � �� � �a t m a a c g t a t g t a t A V c h t, , , , ,( ) ( )� � � � 4 4 , (3) where Am/ V is the section factor for unprotected steel mem- bers, Am is the surface area of the member per unit length. The convective heat transfer coefficient is recommended to have a value of 25 W m�2 K�1. The iterative procedure for protected steelwork is similar to that for unprotected steel. The equation does not require heat transfer coefficients be- cause it is assumed that the external surface of the insulation is at the same temperature as the fire gases. It is also assumed that the internal surface of the insulation is at the same tem- perature as the steel. The equation is � � � � � � � a t p p p a t a p t p a t a p p p t p g A V k d c c c A V d c, , , , , ,( � � � � 2 t a t t� � , ) ,� (4) where Ap /V is the section factor for steel members insulated by fire protection material, kp is the thermal conductivity of the insulation, dp is the thickness of the fire protection mate- rial, cp,t is the temperature independent specific heat of the fire protection material, �p is the thermal conductivity of the fire protection system, �p is the unit mass of the fire protec- tion material. ECCS, see [6], suggested ignoring the heat capacity of the insulation if it is less than half of that of the steel section, such that c A c Aa t a p t p i, ,� �2 , where Ai is the cross-section area of the insulating material and A is the cross-section area of the steel. This prediction is used in EN 1993-1-2: 2003 par. 4.2.5.2 [7], taking constant 3 instead of constant 2 in the heavy insulations term to allow cal- culations for the temperature gradient across the insulation material, in the form � �� � � � � � � a t p p p a a g t a t A V d c t e , , ,( ) ( ) � � � � � � � � � � 1 3 110 � � �� � �g t a t g tif, , ,( )but � 0 0 (5) with � � � � c c d A V p t p a t a p p, , , where Ap is the appropriate area of fire protection material per unit length of the member, which should generally be taken as the area of its inner surface, but for a hollow encasement with a clearance around the steel member the same value as for a hollow encasement without a clearance may be adopted. For prediction we used fire protection material thickness dp � 0.018 m; unit mass �p � 310 kg m �3; specific heat cp � 1200 J kg �1 K�1; and ther- mal conductivity �p � 0.078 W m �1 K�1. Fig. 9 compares of the predicted and measured temperatures. The internal col- umn was exposed from four sides, the external column from two sides only. The prediction is based on the measured gas temperature in thermocouple G525, on the calculated parametric temperature, see [8] and [9], and also on the nominal temperature, see [10]. © Czech Technical University Publishing House http://ctn.cvut.cz/ap/ 135 Acta Polytechnica Vol. 44 No.5–6/2004 0 200 400 600 800 1000 0 30 60 90 120 150 C418, measured Steel temperature, °C Time, min. C414, measured C409, measured E1D1 N E2D2 C415, measured C417, measured D2 C414 500 500 200 C409 C418 C415 C409 C418 150 C415 C414 50 C417 C417 Fig. 8: Measured temperatures along a column length, column D2, and at a beam end The results of modelling the heat transfer into the col- umns by the 2-dimensional FE code are shown in Fig. 10. The Super-Tempcalc code [11], taking into account the above listed parameters, was used for prediction. In the code, the differential equation is derived for 2-dimensional heat flow from conservation of energy, based on the fact that total inflow per unit time equals the total outflow per unit time. The constitutive relation invoked is Fourier’s law of heat conduction, which describes heat flow within a material. The spatial and time domains are discretized by the weighted residual approach. Boundary conditions implemented in- clude convective and radiative heat flow and heat exchange within enclosures. 3-node triangular finite elements were used. The thermal properties of the materials are described as temperature dependent. The temperature distribution within the protected column is presented during heating, after 30 min. of fire, and during cooling, after 120 min. of fire in Fig. 11. A temperature difference of 40 °C only was reached in the section. The comparison of the analytical and numeri- cal results confirms the good quality of the presented analyti- cal model. 5 Conclusions The collapse of the structure or parts of the structure was not reached during the experiment for a fire load of 40 kg m�2, which represents the fire load in a typical office building, together with a mechanical load greater than stan- dard approved cases. The structure showed good structural integrity. The test results supported the concept of unpro- tected beams and protected columns as a viable system for composite floors. The connections do not need to be fire pro- tected from the point of view of its resistance, see Fig. 11b, where only moderate local buckling is visible. 136 © Czech Technical University Publishing House http://ctn.cvut.cz/ap/ Acta Polytechnica Vol. 44 No.5–6/2004 Experimental curve column D2 - C410 N E2D2 E1D1 C410 G525 0 50 100 150 200 250 300 350 400 0 30 60 90 120 150 Steel temperature, °C Time, min. Prediction by 2D FEM from parametric curve, EN 1991-1-2 Prediction by 2D FEM from nominal curve, EN 1991-1-2 from exp. gas temp. G525 Prediction by 2D FEM C410 D2 C410 1848 1848 Fig. 10: Comparison of column calculated temperatures based on prediction by Tempcalc code to measured temperatures, thermocou- ple C410 N E2D2 E1D1 C410 G525 C405 from nominal curve EN 1991-1-2 from exp. gas temp. G525 Measured, C410 from parametric gas temp. internal column D2 Steel temperature, °C Time, min. Prediction by EN1993-1-2, C410 Prediction by EN1993-1-2, C410 Prediction by EN1993-1-2, C410 0 50 100 150 200 250 300 350 400 0 30 60 90 120 150 from exp. gas temp. G525 Prediction by EN 1993-1-2, C405 Measured, C405 external column D1 D2 C410 1848 1848 C410 D1 C405 C405 EN 1991-1-2 Fig. 9: Comparison of column calculated temperatures based on prediction by EN 1993-1-2 with measured temperatures, thermocouple C410 The test in at Cardington on January 16, 2003 documents that the incremental analytical models in prEN-1993-1-2: 2003 [7] allows predict the column temperature from the gas temperature during the heating phase with good accuracy, see Figs. 3, 9 and 10. From the nature of the heat transferred from the connected unprotected beams it is clear that the 3D solution is sufficient to describe the transfer of heat into the protected columns under the unprotected floors. An approxi- mation based on 2D calculations is acceptable for design up to 60 minutes of fire only. Accurate analytical prediction of the temperature of the structure during its cooling will enable optimization of the application of the fire protective material on the compressed member of the structure only. 6 Acknowledgment The authors would like to thank all nineteen members of the project team working on this large scale experiment at the Cardington BRE laboratory from October 2002 till January 2003. Special thanks go to Mr. Tom Lennon, Mr. Nick Petty, and Mr. Martin Beneš for careful measurements of data presented above. The project was supported by the grant of European Community FP5 HPRI - CV 5535. This paper was prepared as a part of project 103/04/2100 of the Czech Grant Agency. References [1] Wang Y. C.: “Steel and composite structures”, Behaviour and design for fire safety, Spon Press, London 2002, ISBN 0-415-24436-6. [2] Bravery P. N. R.: “Cardington Large Building Test Fa- cility, Construction details for the first building”, Build- ing Research Establishment, Internal paper, Watford 1993, p. 158. [3] Moore D. B.: “Steel fire tests on a building framed”, Building Research Establishment, Paper No. PD220/95, Watford 1995, p. 13. [4] Lennon T.: “Cardington fire tests: Survey of damage to the eight storey building”, Building Research Establish- ment, Paper No. 127/97, Watford 1997, p. 56. [5] Wald F., Santiago A., Chladná M., Lennon T., Burges I., Beneš M.: “Tensile membrane action and robustness of structural steel joints under natural fire”, Internal report, Part 1 - Project of Measurements; Part 2 - Predic- tion; Part 3 – Measured data; Part 4 – Behaviour, BRE, Watford, 2002–2003. [6] Buchanan A. H.: “Structural design for fire safety”, John Wiley & Sons, Chichester 2003. ISBN 0-471-89060-X. [7] Eurocode 3: Design of Steel Structures - prEN-1993-1-2: 2004, Part 1.2: “Structural Fire Design”, Final draft, 2003, CEN, Brussels 2003. [8] Wald F., Silva S., Moore D. B, Lennon T., Chladná M., Santiago A., Beneš M.: “Experiment with structure un- der natural fire”, The Structural Engineer, in press. [9] Wald F., Chladná M., Santiago A., Lennon T.: “Temper- atures of structure during Cardington structural integ- rity fire test”, in Proceedings of ICSCS’04, Seoul 2004, in press. [10] Eurocode 1: Actions on structures, prEN-1991-1-2: 2004, Part 1.2: General actions – “Actions on structures exposed to fire”, CEN, Brussels 2002. [11] Anderberg, Y.: “SUPER-TEMPCALC, A commercial and user-friendly computer program with Automatic FE-generation for temperature analysis of structures ex- posed to heat”, Fire Safety Design AB, Lund 1991. Prof. Ing. František Wald, CSc. phone: +420 224 354 757, +420 233 334 766 e-mail: wald@fsv.cvut.cz Department of Steel Structures Ing. Petra Studecká phone: +420 224 353 877 e-mail: studecká@fsv.cvut.cz Ing. Lukáš Kroupa phone: +420 224 354 624 e-mail: lukaskroupa@fsv.cvut.cz Czech Technical University in Prague Faculty of Civil Engineering Thákurova 7 166 29 Praha 6, Czech Republic © Czech Technical University Publishing House http://ctn.cvut.cz/ap/ 137 Acta Polytechnica Vol. 44 No.5–6/2004 30 minutes 100 °C 300 500 700 800 °C 300 °C 120 minutes UC 305x305x137 Cafco300, 18 mm t d t f w h p dpb Fig. 11: a) Temperature distribution within the protected column during heating (after 30 min.) during cooling (after 120 min.) by Tempcalc code; b) local buckling of column flange E2 Annex A – Measured Geometrical Properties of Columns 138 © Czech Technical University Publishing House http://ctn.cvut.cz/ap/ Acta Polytechnica Vol. 44 No.5–6/2004 Profile Column hl hr bupp blow tw tf,upp,l tf,upp,r tf,low,l tf,low,r mm mm mm mm UC305×305×137 nominal 320.5 309.2 13.8 21.7 D2 318.1 316.6 308.2 309.6 – 21.2 21.9 21.2 21.6 E1 318.1 317.6 307.2 309.8 – 21.4 21.6 21.2 21.7 E2 320.2 318.6 309.2 309.6 – 21.4 21.9 21.1 21.5 UC305×305×198 nominal 339.9 314.5 19.1 31.4 D1 336.0 336.8 312.3 312.5 – 32.0 30.8 31.4 31.1 Symbols, see Fig. 11: hl height of the column section on the left side, hr height of the column section on the right side, b is the width of the column sec- tion, upp upper measured value, low lower measured value, tw thickness of the column web, tf thickness of column flange Table A1: Geometry of column, [5] Fig. 2 Column Above floor West (outer) flange prot. thickness East (inner) flange prot. thickness hickness of prot. on web Average of cross section Average on column max. min. max. min. max. min. E1 1000 18 15 18 22 18 20 19 18 2000 18 19 15 20 20 15 18 E2 1000 13 19 23 16 19 21 19 19 2000 22 14 18 20 26 20 20 D1 1000 23 13 18 20 18 16 18 18 2000 22 15 19 18 22 13 18 3000 12 18 15 21 16 – 16 4000 19 13 18 21 22 – 19 D2 1000 22 26 24 – 32 – 26 25 2000 26 19 20 – 30 – 24 Table A2: Thickness of the thermal protection of the column dp (mm), [5], Fig. 11 Annex B – Measured Temperature © Czech Technical University Publishing House http://ctn.cvut.cz/ap/ 139 Acta Polytechnica Vol. 44 No.5–6/2004 Thermocouple Time interval, min. C 521 C 522 C 523 C 524 C 525 C 526 C 527 C 528 aver. 10 – 15 356.40 321.00 349.50 370.40 399.00 422.80 386.00 358.20 373 25 – 30 687.6 660.1 698.3 762.6 806.8 838.0 827.6 782.4 805 40 – 45 810.5 777.3 834.8 851.1 935.0 971.6 964.5 885.9 966 0 – 180 1 015.3 1 016.1 1 007.3 990.5 1 107.8 1 096.3 1 063.1 979.8 1 074 75 – 80 769.6 796.2 730.5 697.2 762.6 754.5 735.0 662.2 761 90 – 95 567.1 579.7 576.9 528.7 560.3 535.0 555.1 475.1 555 Table B1: Maximum gas temperatures (°C) in time intervals, thermocouples 300 mm under ceiling, number of thermocouples, see Fig. 2 [5] Column D1 D2 D2 D2 D2 D2-D1 D2 E2 E2 E2 Time, min. C 401 C 408 C 409 C 410 C 411 C 415 C 418 C 428 C 430 C 433 0 17.6 17.6 16.9 16.1 16.3 22.6 18.4 15.9 15.9 15.9 15 18.0 23.2 22.2 23.4 23.2 106.2 26.6 19.8 20.8 21.2 30 31.0 85.0 82.9 82.5 89.4 521.2 84.8 73.3 74.6 76.2 45 61.3 106.9 106.8 109.9 107.4 726.0 141.7 107.3 107.6 109.0 60 88.7 191.5 205.5 215.1 208.8 976.0 266.6 174.3 197.8 202.7 90 95.2 408.8 401.3 385.8 421.7 704.6 489.4 377.8 380.3 385.8 106 92.5 426.0 421.8 415.9 434.9 522.2 511.2 400.0 402.3 416.6 124 84.6 413.1 410.8 402.5 408.7 365.6 495.5 392.2 390.9 408.1 160 73.2 367.4 367.3 355.0 354.1 215.2 411.5 352.1 345.7 358.7 Maximal 95.3 426.0 421.8 415.9 436.3 985.8 511.2 410.4 402.3 416.6 Position 3/4 SW 3/4 SW 3/4 SE 1/2 NW 1/2 N **BF *NW 3/4 SW 1/2 SW 1/4 SW The thermocouples were located 20 mm from the column/beam edge; * 200 mm below secondary beam; ** on the beam lower flange of the beam, 200 mm from the column face. Table B2: Steel beam temperatures (°C), numbers of thermocouples, see Figs. 2 and 5 [5]