Behavior of Composite Slim Floor Structures in Fire
Publication: Journal of Structural Engineering
Volume 126, Issue 7
Abstract
In recent years, increasing interest has been shown throughout Europe in developing and designing slim floor systems in steel-framed buildings. This paper presents the fire resistance behavior of the composite asymmetric slim floor beam as an isolated member and as a part of the frame using numerical analysis methods. Three schemes were investigated, including isolated beams, a plane subframe with semirigid beam-to-column connections, and a 3D slim floor frame system. The first scheme aimed to explore the fire resistance of the beams according to standard fire-testing methodology. The objective of the second scheme was to reveal the effect of frame continuity on the fire resistance of the slim floor beam and the mechanical interaction between the frame elements. The third scheme was to preliminarily identify the influence of the composite slab on the beam behavior in fire. The investigations show that the isolated slim floor beam has a 60-min standard fire resistance without any additional fire protection, if the load ratio is <0.5. As a part of the frame, the beam still keeps its stability even when the temperature of the bottom steel flange of the beam reaches up to 900°C (90-min ISO fire exposure). The analyzed results indicate that the axial restraints provided by the surrounding parts cause a larger deformation of the beam in the earlier ISO heating phase and a more stable behavior thereafter. The rotational restraints essentially cause the change in the applied load ratio in fire, which can be quantified using the “modified load ratio” proposed in this paper.
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References
1.
ABAQUS/Standard user's manual (version 5.7). (1997). Hibbitt, Karlsson & Sorensen Inc.
2.
Baily, C. G. (1999). “The behaviour of asymmetric slim floor steel beams in fire.” J. Constr. Steel Res., 50, 235–257.
3.
Baily, C. G., Burgess, I., and Plank, R. (1997). “Bridging and restraint effects of localised fires in composite frame structures.” Proc., Int. Conf. Compos. Constr., 379–384.
4.
Baily, C. G., Lennon, T., and Moore, D. B. (1999). “The behaviour of full-scale steel-framed building subjected to compartment fires.” The Struct. Engr., London, 77(8), 15–21.
5.
British Standards Institute (BSI). ( 1990). “BS 5950: Part 8. Code of practice for fire resistance design.” Structural use of steelwork in buildings, United Kingdom.
6.
Commission of the European Communities. ( 1992). “Design of composite steel and concrete structures: Part 1.1—General rules and rules for buildings.” Eurocode 4, Brussels.
7.
Johnson, P. F. (1998). “International developments in fire engineering of steel structures.” J. Constr. Steel Res., 46(1–3).
8.
Lawson, R. M., Mullett, D. L., and Rackham, J. W. ( 1997). “Design of asymmetric `Slimflor' beams using deep composite decking.” SCI P175, The Steel Construction Institute, Berkshire, U.K.
9.
Lu, X., and Mäkeläinen, P. (1996). “Slim floor development in Sweden and Finland.” Struct. Engrg. Int., 2, 127–129.
10.
Ma, Z., and Mäkeläinen, P. ( 1999a). “Temperature analysis of composite steel-concrete slim floor structures exposed to fire.” TKK-TER-10, Lab. of Steel Struct., Helsinki University of Technology, Espoo, Finland.
11.
Ma, Z., and Mäkeläinen, P. ( 1999b). “Numerical analysis of steel-concrete composite slim floor structures in fire.” TKK-TER-11, Lab. of Steel Struct., Helsinki University of Technology, Espoo, Finland.
12.
Mullett, D. L., and Lawson, R. M. ( 1993). “Slim floor construction using deep decking.” SCI P127, The Steel Construction Institute, Berkshire, U.K.
13.
Newman, G. M. (1995). “Fire resistance of slim floor beams.” J. Constr. Steel Res., 33(1–2), 87–100.
14.
Newman, G. M. (1996). “Design implications of the Cardington fire research programme.” Proc., 2nd Cardington Conf., 161–168.
15.
O'Connor, M. A. (1996). “Numerical modelling of composite structures subjected to thermal loading.” Proc., 2nd Cardington Conf., 127–131.
16.
Robinson, J., and Newman, G. M. (1997). “Cardington fire tests: First results.” New Steel Constr., 5(3), 23–27.
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Received: Oct 13, 1999
Published online: Jul 1, 2000
Published in print: Jul 2000
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