Structural Engineering and Mechanics

Techno-Press (테크노프레스)
권호 표지
DOI QR코드

DOI QR Code

Reliability studies on RC beams exposed to fire based on IS456:2000 design methods

  • Balaji, Aneesha (Department of Civil Engineering, National Institute of Technology) ;
  • Aathira, M.S. (Department of Civil Engineering, National Institute of Technology) ;
  • Pillai, T.M. Madhavan (Department of Civil Engineering, National Institute of Technology) ;
  • Nagarajan, Praveen (Department of Civil Engineering, National Institute of Technology)
  • Received : 2015.11.16
  • Accepted : 2016.05.05
  • Published : 2016.09.10
⟨ Previous Next ⟩

Abstract

This paper examines a methodology for computing the probability of structural failure of reinforced concrete beams subjected to fire. The significant load variables considered are dead load, sustained live load and fire temperature. Resistance is expressed in terms of moment capacity with random variables taken as yield strength of steel, concrete class (or grade of concrete), beam width and depth. The flexural capacity is determined based on the design equations recommended in Indian standard IS456:2000. Simplified method named $500^{\circ}C$ isotherm method detailed in Eurocode 2 is incorporated for fire design. A transient thermal analysis is conducted using finite element software ANSYS$^{(R)}$ Release15. Reliability is evaluated from the initial state to 4h of fire exposure based on the first order reliability method (FORM). A procedure is coded in MATLAB for finding the reliability index. This procedure is validated with available literature. The effect of various parameters like effective cover, yield strength of steel, grade of concrete, distribution of reinforcement bars and aggregate type on reliability indices are studied. Parameters like effective cover of concrete, yield strength of steel has a significant effect on reliability of beams. Different failure modes like limit state of flexure and limit state of shear are checked.

Keywords

References

  1. ACI 216.1-07 (2007), Code requirements for determining fire resistance of concrete and masonry construction assemblies, American Concrete Institute, Farmington hills, MI.
  2. ASTM E119-01 (2001), Standard Methods of Fire Test of Building Construction and Materials, American Society for Testing and Materials, West Conshohocken, Pennsylvania.
  3. Balaji, A., Luquman M.K., Nagarajan, P. and Madhavan Pillai, T.M. (2016), "Studies on the behavior of reinforced concrete short column subjected to fire", Alex. Eng. J., 55(1), 475-486. https://doi.org/10.1016/j.aej.2015.12.022
  4. Balaji, A., Nagarajan, P. and Madhavan Pillai, T.M. (2015), "Validation of indian standard code provisions for fire resistance of flexural elements", Songlanakarin J. Sci. Tech., 37, 183-192.
  5. Eamon, C.D. and Jensen, E. (2012), "Reliability analysis of prestressed concrete beams exposed to fire", Eng. Struct., 43, 69-77. https://doi.org/10.1016/j.engstruct.2012.05.016
  6. Eamon, C.D. and Jensen, E. (2013a), "Reliability analysis of RC beams exposed to fire", J. Struct. Eng., 139, 212-220. https://doi.org/10.1061/(ASCE)ST.1943-541X.0000614
  7. Eamon, C.D. and Jensen, E. (2013b), "Reliability analysis of reinforced concrete columns exposed to fire", Fire Saf. J., 62, 221-229. https://doi.org/10.1016/j.firesaf.2013.10.002
  8. Eurocode 2 (2004), Design of concrete structures- Part 1-2: General rules- Structural Fire Design (EN 1992-1-2), Commission of European Committee for Standardization, Brussels.
  9. IS 3809 (1979), Fire resistance test of structures, Bureau of Indian Standards, New Delhi.
  10. IS 456 (2000), Plain and reinforced concrete- Code of Practice, Fourth revision, Bureau of Indian Standards, New Delhi.
  11. IS 875-part 2-1987 (2003), Plain and reinforced concrete- Code of practice for design loads (other than earth quake) for buildings and structures, Bureau of Indian Standards, New Delhi.
  12. ISO 834-1 (1999), Fire resistance tests-elements of building construction, Part1: General requirement, International Organization for Standardization, Geneva.
  13. Kodur, V.K.R. and Dwaikat, M. (2008), "Flexural response of reinforced concrete beams exposed to fire", Struct. Concrete, 9(1), 45-54. https://doi.org/10.1680/stco.2008.9.1.45
  14. Le, J. and Xue, B. (2014), "Probabilistic analysis of reinforced concrete frame structures against progressive collapse", Eng. Struct., 76, 313-323. https://doi.org/10.1016/j.engstruct.2014.07.016
  15. Lu, R., Luo, Y. and Conte, J.P. (1994), "Reliability evaluation of reinforced concrete beams", Struct. Saf., 14, 277-298. https://doi.org/10.1016/0167-4730(94)90016-7
  16. Madson, H.O., Krenk, S. and Lind, N.C. (1986), Methods of Structural Safety, Prentice Hall Inc., Englewood Cliffs, New Jersey, USA.
  17. Melchers, R.E. (2002), Structural Reliability Analysis and Prediction, John Weily & Sons Ltd, New York.
  18. Petterson, O. (1994), "Rational structural fire engineering design based on simulated real fire exposure", Fire Safety Science- Proceedings of the Fourth International Symposium, International Association for Fire Safety Science, 3-26.
  19. Ranganathan, R. (1990), Reliability Analysis and Design of Structures, Tata McGraw-Hill Publishing Company Limited, New Delhi.
  20. Shi, X. and Tan, T. (2004), "Influence of concrete cover on fire resistance of reinforced concrete flexural elements", J. Struct. Eng., 130, 1225-1232. https://doi.org/10.1061/(ASCE)0733-9445(2004)130:8(1225)
  21. Stepinac, M., Rajcic, V., Androic, B. and Cizmar, D. (2012), "Reliability of glulam beams exposed to fire", World Conference on Timber Engineering, Auckland, New Zealand, July.
  22. Torii, A.J. and Machado, R.D. (2010), "Reliability analysis of nonlinear reinforced concrete beams", Mecanica Comput., 29, 6847-6863.
  23. Wang, Z., Qiao, M., Zhu, D. and Han, Y. (2010), "The reliability analysis of reinforced concrete beams under high temperature", Proceedings of the 3rd International Joint Conference on Computational Science and Optimization, IEEE Computer Society, Washington, DC, 327-330.
  24. Wickstrom, U. (1986), "A very simple method for estimating temperature in fire exposed concrete structures", Fire Technology Technical Report, SP-RAPP, Swedish National Testing Institute, Boras, Sweden.

Cited by

  1. Behavior of prestressed concrete box bridge girders Under hydrocarbon fire condition vol.210, 2017, https://doi.org/10.1016/j.proeng.2017.11.100
  2. A numerical method for evaluating fire performance of prestressed concrete T bridge girders vol.25, pp.6, 2020, https://doi.org/10.12989/cac.2020.25.6.497
  3. Framework for fragility assessment of reinforced concrete portal frame subjected to elevated temperature vol.28, pp.None, 2016, https://doi.org/10.1016/j.istruc.2020.10.078
  4. Member and structural fragility of reinforced concrete structure under fire vol.11, pp.4, 2020, https://doi.org/10.1108/jsfe-02-2019-0015
  5. An experimental and numerical analysis of concrete walls exposed to fire vol.77, pp.6, 2021, https://doi.org/10.12989/sem.2021.77.6.819