The load-bearing of composite slabs with steel deck under natural fires

Marcílio M. A. Filho; Paulo A. G. Piloto; Carlos Balsa; Marcílio M. A. Filho; Paulo A. G. Piloto; Carlos Balsa

doi:10.3934/matersci.2022010

AIMS Materials Science

2022, Volume 9, Issue 1: 150-171. doi: 10.3934/matersci.2022010

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The load-bearing of composite slabs with steel deck under natural fires

1.
ISISE, Department of Civil Engineering, Universidade do Minho, Campus Azurém, 4800-058, Portugal
2.
LAETA INEGI, Instituto Politécnico de Bragança, Campus Santa Apolónia, 5300-253, Portugal
3.
Research Centre in Digitalization and Intelligent Robotics (CeDRI), Instituto Politécnico de Bragança, Campus Santa Apolónia, 5300-253, Portugal

Received: 24 November 2021 Revised: 28 December 2021 Accepted: 09 January 2022 Published: 28 January 2022

Composite slabs with steel deck combine the load-bearing resistance of the steel deck and rebar with the compressive resistance of the concrete (components). Unprotected composite slabs may be exposed to natural fire conditions from below, and steel reduces its load-bearing capacity during the heating stage. In short fire events, with limited deformations, the composite slabs can recover the load-bearing capacity during the cooling stage. This research presents the validation of the numerical model and the development of a parametric study, to evaluate the load-bearing capacity during the fire event. This method includes a time step procedure, based on the average temperature calculation for each component, including the reduction coefficients applied to the design strength of each material. A new proposal is also presented to evaluate the residual load-bearing capacity. In some circumstances, the residual load-bearing can be reduced by more than 20%. The results showed that the highest variation in the load-bearing resistance of composite slabs occurs when the steel temperatures are between 20 and 600 ℃, after this temperature, the steel has already lost most of its mechanical strength. Moreover, it was observed that different heating rates and different cooling rates influence the rate of the reduction and recovery of the load-bearing capacity. It was also noticed that the lowest load-bearing capacity of the composite slabs was reached after the end of the heating phase, showing that the stability of the element during the heating phase does not guarantee fire safety during the cooling phase.
- composite slabs,
- steel deck,
- natural fire,
- load-bearing,
- residual resistance
Citation: Marcílio M. A. Filho, Paulo A. G. Piloto, Carlos Balsa. The load-bearing of composite slabs with steel deck under natural fires[J]. AIMS Materials Science, 2022, 9(1): 150-171. doi: 10.3934/matersci.2022010

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Abstract

Composite slabs with steel deck combine the load-bearing resistance of the steel deck and rebar with the compressive resistance of the concrete (components). Unprotected composite slabs may be exposed to natural fire conditions from below, and steel reduces its load-bearing capacity during the heating stage. In short fire events, with limited deformations, the composite slabs can recover the load-bearing capacity during the cooling stage. This research presents the validation of the numerical model and the development of a parametric study, to evaluate the load-bearing capacity during the fire event. This method includes a time step procedure, based on the average temperature calculation for each component, including the reduction coefficients applied to the design strength of each material. A new proposal is also presented to evaluate the residual load-bearing capacity. In some circumstances, the residual load-bearing can be reduced by more than 20%. The results showed that the highest variation in the load-bearing resistance of composite slabs occurs when the steel temperatures are between 20 and 600 ℃, after this temperature, the steel has already lost most of its mechanical strength. Moreover, it was observed that different heating rates and different cooling rates influence the rate of the reduction and recovery of the load-bearing capacity. It was also noticed that the lowest load-bearing capacity of the composite slabs was reached after the end of the heating phase, showing that the stability of the element during the heating phase does not guarantee fire safety during the cooling phase.

References

[1]	Jiang J, Main JA, Weigand JM, et al. (2018) Thermal performance of composite slabs with profiled steel decking exposed to fire effects. Fire Safety J 95: 25-41. https://doi.org/10.1016/j.firesaf.2017.10.003 doi: 10.1016/j.firesaf.2017.10.003
[2]	Pantousa D, Mistakidis E (2013) Advanced modeling of composite slabs with thin-walled steel sheeting submitted to fire. Fire Technol 49: 293-327.https://doi.org/10.1007/s10694-012-0265-x doi: 10.1007/s10694-012-0265-x
[3]	Neves IC, Rodrigues JPC, Loureiro ADP (1996) Mechanical properties of reinforcing and prestressing steels after heating. J Mater Civil Eng 8: 189-194. https://doi.org/10.1061/(ASCE)0899-1561(1996)8:4(189) doi: 10.1061/(ASCE)0899-1561(1996)8:4(189)
[4]	Kodur V (2014) Properties of concrete at elevated temperatures. ISRN Civ Eng 2014: 468510. https://doi.org/10.1155/2014/468510 doi: 10.1155/2014/468510
[5]	Chan YN, Peng GF, Anson M (1999) Residual strength and pore structure of high-strength concrete and normal strength concrete after exposure to high temperatures. Cement Concrete Comp 21: 23-27. https://doi.org/10.1016/S0958-9465(98)00034-1 doi: 10.1016/S0958-9465(98)00034-1
[6]	Gillie M, Usmani A, Rotter M, et al. (2001) Modelling of heated composite floor slabs with reference to the Cardington experiments. Fire Safety J 36: 745-767. https://doi.org/10.1016/S0379-7112(01)00038-8 doi: 10.1016/S0379-7112(01)00038-8
[7]	Li GQ, Zhang N, Jiang J (2017) Experimental investigation on thermal and mechanical behaviour of composite floors exposed to standard fire. Fire Safety J 89: 63-76. https://doi.org/10.1016/j.firesaf.2017.02.009 doi: 10.1016/j.firesaf.2017.02.009
[8]	Filho MMA (2020) Influence of the cooling phase in the fire resistance of composite slabs with steel deck [Master's thesis]. Instituto Politécnico de Bragança/Instituto Federal Alagoas (In Portuguese). Available from: http://hdl.handle.net/10198/23536.
[9]	Nguyen MP, Nguyen TT, Tan KH (2018) Temperature profile and resistance of flat decking composite slabs in- and post-fire. Fire Safety J 98: 109-119. https://doi.org/10.1016/j.firesaf.2018.04.001 doi: 10.1016/j.firesaf.2018.04.001
[10]	Nguyen MP, Nguyen TT, Tan KH (2017) Assessment of damage and residual load bearing capacity of a concrete slab after fire: Applied reliability-based methodology. Eng Struct 150: 969-985. https://doi.org/10.1016/j.engstruct.2017.07.078 doi: 10.1016/j.engstruct.2017.07.078
[11]	CEN-European Committee for Standardization (2020) Fire resistance tests-Part 1 : General requirements. EN 1363-1.
[12]	CEN-European Committee for Standardization (2005) Eurocode 4-Design of composite steel and concrete structures-Part 1-2: General rules-Structural fire design. EN 1994-1-2.
[13]	Jiang J, Pintar A, Weigand JM, et al. (2019) Improved calculation method for insulation-based fire resistance of composite slabs. Fire Safety J 105: 144-153. https://doi.org/10.1016/j.firesaf.2019.02.013 doi: 10.1016/j.firesaf.2019.02.013
[14]	Bolina F, Tutikian B, Rodrigues JPC (2021) Thermal analysis of steel decking concrete slabs in case of fire. Fire Safety J 121: 103295. https://doi.org/10.1016/j.firesaf.2021.103295 doi: 10.1016/j.firesaf.2021.103295
[15]	Lamont S, Usmani AS, Drysdale DD (2001) Heat transfer analysis of the composite slab in the Cardington frame fire tests. Fire Safety J 36: 815-839. https://doi.org/10.1016/S0379-7112(01)00041-8 doi: 10.1016/S0379-7112(01)00041-8
[16]	Guo S, Bailey CG (2011) Experimental behaviour of composite slabs during the heating and cooling fire stages. Eng Struct 33: 563-571. https://doi.org/10.1016/j.engstruct.2010.11.014 doi: 10.1016/j.engstruct.2010.11.014
[17]	Guo S (2012) Experimental and numerical study on restrained composite slab during heating and cooling. J Constr Steel Res 69: 95-105. https://doi.org/10.1016/j.jcsr.2011.08.009 doi: 10.1016/j.jcsr.2011.08.009
[18]	CEN-European Committee for Standardization (2009) Fire classification of construction products and building elements. EN 13501-2.
[19]	CEN-European Committee for Standardization (2014) Fire resistance tests for loadbearing elements-Part 2: Floors and roofs. EN 1365-2
[20]	Both C (1998) The fire resistance of composite steel-concrete slabs [PhD's thesis]. Delft University Press.
[21]	Piloto PAG, Prates LMS, Balsa C, et al. (2018) Numerical simulation of the fire resistance of composite slabs with steel deck. Int J Eng Technol 7: 83-86. https://doi.org/10.14419/ijet.v7i2.23.11889 doi: 10.14419/ijet.v7i2.23.11889
[22]	Piloto P, Prates L, Balsa C, et al. (2019) Fire resistance of composite slabs with steel deck: From Experiments to numerical simulation. Mecâ nica Exp 31: 85-94.
[23]	Piloto PAG, Balsa C, Ribeiro F, et al. (2021) Computational simulation of the thermal effects on composite slabs under fire conditions. Math Comput Sci 15: 155-171. https://doi.org/10.1007/s11786-020-00466-0 doi: 10.1007/s11786-020-00466-0
[24]	Piloto PAG, Balsa C, Santos LMC, et al. (2020) Effect of the load level on the resistance of composite slabs with steel decking under fire conditions. J Fire Sci 38: 212-231. https://doi.org/10.1177/0734904119892210 doi: 10.1177/0734904119892210
[25]	Jiang J, Cai W, Chen W, et al. (2021) An insight into eurocode 4 design rules for thermal behaviour of composite slabs. Fire Safety J 120: 03084. https://doi.org/10.1016/j.firesaf.2020.103084 doi: 10.1016/j.firesaf.2020.103084
[26]	CEN-European Committee for Standardization (2002) Eurocode 1: Actions on structures-Part 1-2: General actions-Actions on structures exposed to fire. EN 1991-1-2.
[27]	CEN-European Committee for Standardization (2005) Eurocode 3: Design of steel structures-Part 1-2: General rules-Structural fire design. EN 1993-1-2.
[28]	Çengel YA, Ghajar AJ (2015) Heat and Mass Transfer: Fundamentals and Applications, 5 Eds., New York: McGraw-Hill Education.
[29]	ISO (1999) Fire-resistance tests-Elements of building construction. ISO 834.
[30]	Tao Z, Wang XQ, Uy B (2013) Stress-strain curves of structural and reinforcing steels after exposure to elevated temperatures. J Mater Civ Eng 25: 1306-1316. https://doi.org/10.1061/(ASCE)MT.1943-5533.0000676 doi: 10.1061/(ASCE)MT.1943-5533.0000676
[31]	Piloto PAG, Mesquita L, Real PV, et al. (2002) Steel mechanical properties evaluated at room temperature after being submitted at fire conditions. XXX Iahs World Congress on Housing, Housing Construction: an Interdisciplinary Task, 1-3.
[32]	Hamerlinck AF (1991) The Behaviour of Fire-Exposed Composite Steel/Concrete Slabs, Eindhoven University of Technology.
[33]	Gernay T, Franssen J (2015) A performance indicator for structures under natural fire. Eng Struct 100: 94-103. https://doi.org/10.1016/j.engstruct.2015.06.005 doi: 10.1016/j.engstruct.2015.06.005

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