[en] For most fires occurring in buildings with a concrete structural frame, the structural elements do not collapse during fire exposure, and further use of the building after fire may be possible. Fire can nevertheless result in a permanent loss of strength and thus a post-fire evaluation of the residual load bearing capacity has to be made to inform decisions on continued use and the need for structural repairs. This evaluation is however particularly difficult due to the many uncertainties associated with both the fire exposure and the characteristics of the structural elements. These uncertainties cannot be neglected when determining the residual capacity since adequate safety is a major societal concern as indicated by the predominance of safety in current design standards and guidance documents. In this paper a comprehensive methodology is presented for the assessment of the residual capacity of concrete structures after exposure to fire. The methodology is introduced through application to a real-life case study of an apartment fire with a focus on the end-span of the affected continuous concrete slab. It results in a reliability-based evaluation of the maximum allowable characteristic value for the imposed load on the slab. The presented methodology is useful to make informed decision about continued use of structures after a fire event.
Disciplines :
Civil engineering
Author, co-author :
Molkens, Tom; StuBeCo bvba & Sweco Belgium nv
Van Coile, Ruben; University of Ghent
Gernay, Thomas ; Université de Liège > Département ArGEnCo > Ingénierie du feu
Language :
English
Title :
Assessment of damage and residual load bearing capacity of a concrete slab after fire: Applied reliability-based methodology
Annerel, E., Assessment of the residual strength of concrete structures after fire exposure. Doctoral dissertation, 2010, Ghent University, Belgium.
Bocchini, P., Asce, M., Frangopol, D.M., Asce, D.M., Ummenhofer, T., Zinke, T., Resilience and sustainability of civil infrastructure: toward a unified approach. J Inf Syst 20:2 (2014), 1–16, 10.1061/(ASCE)IS.1943-555X.0000177.
Burnham, K.P., Anderson, D.R., Model selection and multimodel inference: a practical information-theoretic approach. 2002, Springer, New York.
Cadorin J-F, Franssen J-M, A tool to design steel elements submitted to compartment fires OZone V2. Part 1: Pre- and post-flashover compartment fire model. Fire Saf J, Elsevier 2003;38:395–427. < http://hdl.handle.net/2268/29650>.
Chen, Y.-H., Chang, Y.-F., Yao, G.C., Sheu, M.-S., Experimental research on post-fire behavior of reinforced concrete columns. Fire Saf J 44 (2009), 741–748.
El-Hawary, M.M., Ragab, A.M., Abd El-Azim, A., Elibiari, S., Effect of fire on flexural behavior of RC beams. Constr Build Mater 10:2 (1996), 147–150.
EN 1990. Eurocode 0: basis of structural design. European Committee for Standardization CEN; 2002.
EN 1991-1-1. Eurocode 1: actions on structures – part 1–2: general actions – densities, self-weight, imposed loads for buildings. European Committee for Standardization CEN; 2002.
EN 1991-1-2. Eurocode 1: actions on structures – part 1–2: general actions – actions on structures exposed to fire. European Committee for Standardization CEN; 2002.
EN 1992-1-2. Eurocode 2: design of concrete structures – part 1–2: general rules – structural fire design. European Committee for Standardization CEN; 2005.
EN 1994-1-2. Eurocode 4: design of composite steel and concrete structures – part 1–2: general rules – structural fire design. European Committee for Standardization CEN; 2005.
EN 1996-1-2. Eurocode 6: design of masonry structures – part 1–2: general rules – structural fire design. European Committee for Standardization CEN; 2005.
EU, Regulation No 305/2011 of the European Parliament and of the Council of 9 March 2011 laying down harmonised conditions for the marketing of construction products and repealing Council Directive 89/106/EEC. Off J Eur Union 54:L88 (2011), 5–43.
Felicetti R, Gambarova PG, Silva M, Vimercati M. Thermal diffusivity and residual strength of high-performance light-weight concrete exposed to high temperature. 6th Int Symp on Utilization of HSC/HPC, Leipzig; 2002. p. 935–48.
Franssen, J.-M., Gernay, T., Modeling structures in fire with SAFIR®: theoretical background and capabilities. J Struct Fire Eng, 2017, 10.1108/JSFE-07-2016-0010.
Franssen, J.M., SAFIR. A thermal/structural program modelling structures under fire. Eng J, A.I.S.C. 42:3 (2005), 143–158.
Gernay, T., Franssen, J.-M., A formulation of the Eurocode 2 concrete model at elevated temperature that includes an explicit term for transient creep. Fire Saf J 51 (2012), 1–9.
Gernay, T., Millard, A., Franssen, J.-M., A multiaxial constitutive model for concrete in the fire situation: theoretical formulation. Int J Solids Struct 50:22–23 (2013), 3659–3673.
Gernay, T., Franssen, J.-M., A plastic-damage model for concrete in fire: applications in structural fire engineering. Fire Saf J 71 (2015), 268–278.
Gulvanessian, H., Calgaro, J.-A., Holický, M., Designer's guide to EN 1990: Eurocode 0: Basis for structural design. 2002, Thomas Telford, London.
Holický M, Sýkora M. Stochastic models in analysis of structural reliability. Proceedings of the international symposium on stochastic models in reliability engineering, life sciences and operation management. 08-11/02, Beer Sheva, Israel; 2010.
Ioannou, I., Aspinall, W., Rush, D., Bisby, L., Rossetto, T., Expert judgment-based fragility assessment of reinforced concrete buildings exposed to fire. Rel Eng Syst Saf 167 (2017), 105–127.
Jau, W.-C., Huang, K.-L., A study of reinforced concrete corner columns after fire. Cem Concr Compos 30 (2008), 622–638.
JCSS, Probabilistic model code. The joint committee on structural safety, 2007 Available online at www.jcss.byg.dtu.dk.
Kodur, V.K.R., Raut, N.K., Mao, X.Y., Khaliq, W., Simplified approach for evaluating residual strength of fire-exposed reinforced concrete columns. Mater Struct 46 (2013), 2059–2075.
Kodur, V.K.R., Agrawal, A., An approach for evaluating residual capacity of reinforced concrete beams exposed to fire. Eng Struct 110 (2016), 293–306.
Lange, D., Devaney, S., Usmani, A., An application of the PEER PBEE framework to structures in fire. Eng Struct 66 (2014), 100–115.
Mostafaei H. et al. Resilience of critical infrastructure to extreme fires – gaps and challenges. Report DRDC-RDDC-2014-C66, NRC, Canada; 2014. 73p.
NBN B15-103. Design of reinforced concrete. Belgian Institute for Standards BIN; 1977.
Rackwitz, R., Fiessler, B., Structural reliability under combined random load sequences. Comput Struct 9:5 (1978), 489–494.
Raouffard, M.M., Nishiyama, M., Residual load bearing capacity of reinforced concrete frames after fire. J Adv Concr Technol 14 (2016), 625–633.
Schneider U, editor. Properties of materials at high temperatures: concrete, RILEM. Kassel: Univ. of Kassel; 1985.
Spinardi, G., Bisby, L., Torero, J., A review of sociological issues in fire safety regulation. Fire Technol 53 (2017), 1011–1037.
Torrent, R.J., Bisby, L., Torero, J., The log-normal distribution: a better fitness for the results of mechanical testing of materials. Mater Struct 11 (1978), 235–245.
Van Coile, R., Caspeele, R., Taerwe, L., Towards a reliability-based post-fire assessment method for concrete slabs incorporating data from inspection. Struct Concr 15:3 (2014), 395–407.
Van Coile, R., Reliability-based decision making for concrete elements exposed to fire. Doctoral dissertation, 2015, Ghent University, Belgium.
Van Coile, R., Caspeele, R., Taerwe, L., Post-fire safety of concrete columns: an engineering-oriented reliability-based assessment tool. Proceedings of applications of structural fire engineering (ASFE 2015). 15-16/10, Dubrovnik, Croatia, 2015.
Van Coile R. Post-fire residual bending capacity for concrete slabs: probabilistic evaluation, limiting isotherm and stochastic correction factor; unpublished manuscript.
