Simple Method for Predicting Temperatures in Reinforced Concrete Beams Exposed to a Standard Fire

In performance-based fire safety design, the fire performance of a structure needs to be accurately evaluated, which requires the accurate prediction of temperatures in the structure. While a finite-element or a finite-difference analysis may be carried out for this purpose, structural engineers generally prefer a simpler method. This paper therefore presents a simple, design-oriented method for predicting temperatures in RC beams under a standard fire exposure. Results from finite element heat transfer analysis are first examined to identify the key parameters that determine temperature distributions in RC beams. On the basis of this knowledge, a simple method in the form of handy formulae and diagrams is derived from regression analysis of finite element temperature data, with due consideration of the effects of beam geometry and fire exposure duration. The accuracy of the proposed method is demonstrated by comparing its predictions with temperature data from both finite element analysis and laboratory tests. The proposed method is believed to be attractive to practicing engineers for use in the fire resistance evaluation of RC beams exposed to a standard fire because of its simplicity and accuracy.

[1]  Tz Harmathy,et al.  Comparison of severity of exposure in ASTM E 119 and ISO 834 fire resistance tests , 1987 .

[2]  Christopher D. Eamon,et al.  Reliability analysis of prestressed concrete beams exposed to fire , 2012 .

[3]  Jean-Marc Franssen,et al.  The use of numerical models for the fire analysis of reinforced concrete and composite structures , 1985 .

[4]  S. B. Desai,et al.  Design of reinforced concrete beams under fire exposure conditions , 1998 .

[5]  Asif Usmani,et al.  Bonded Fibre Reinforced Polymer Strengthening in a Real Fire , 2009 .

[6]  John Purkiss,et al.  Fire Safety Engineering Design of Structures : Design of Structures, Second Edition , 2007 .

[7]  Paul J. Hogg,et al.  A model for predicting the properties of the constituents of a glass fibre rebar reinforced concrete beam at elevated temperatures simulating a fire test , 2005 .

[8]  B Ellingwood,et al.  FLEXURAL AND SHEAR BEHAVIOR OF REINFORCED CONCRETE BEAMS DURING FIRE TESTS , 1988 .

[9]  A. W. Beeby,et al.  Designers Guide to EN 1992-1-1 and EN 1992-1-2 Eurocode 2: Design of Concrete Structures. General rules and rules for buildings and structural fire design , 2005 .

[10]  L P Mercer,et al.  General model for nutritional responses of higher organisms. , 1975, Proceedings of the National Academy of Sciences of the United States of America.

[11]  Venkatesh Kodur,et al.  A simplified approach for predicting temperature in reinforced concrete members exposed to standard fire , 2013 .

[12]  T. Z. Harmathy,et al.  Fire safety design and concrete , 1993 .

[13]  J. Clarke.  Structural design of polymer composites : EUROCOMP design code and handbook , 1996 .

[14]  Daniel Di Capua,et al.  Nonlinear analysis of reinforced concrete cross-sections exposed to fire , 2007 .

[15]  Chanakya Arya,et al.  Buckling resistance of unstiffened webs , 2009 .

[16]  G. Manfredi,et al.  Behavior of FRP Reinforced Concrete Slabs in Case of Fire: Theoretical Models and Experimental Tests , 2012 .

[17]  Ricardo Hallal Fakury,et al.  Interaction diagrams for reinforced concrete sections subjected to fire , 2010 .

[18]  Satish Balkrishna Desai,et al.  Shear resistance at normal and high temperatures of reinforced concrete members with links and central bars , 1995 .

[19]  Venkatesh Kodur,et al.  Response of Restrained Concrete Beams under Design Fire Exposure , 2009 .

[20]  Muhammad Masood Rafi,et al.  Fire Performance of Frp Reinforced Concrete Beams , 2010 .

[21]  T. Harmathy,et al.  Effect of Moisture on the Fire Endurance of Building Elements , 1965 .

[22]  Johan Rigberth.  Simplified Design of Fire Exposed Concrete Beams and Columns. , 2000 .

[23]  Fabio Biondini,et al.  Cellular Finite Beam Element for Nonlinear Analysis of Concrete Structures under Fire , 2011 .

[24]  Wan-Yang Gao,et al.  Finite element modeling of reinforced concrete beams exposed to fire , 2013 .

[25]  T. D. Lin,et al.  FIRE ENDURANCE OF CONTINUOUS REINFORCED CONCRETE BEAMS , 1981 .

[26]  John Purkiss,et al.  Fire Safety Engineering Design of Structures , 1996 .

[27]  Stephanie L. Walkup,et al.  Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures (ACI 440.2R-02) , 2005 .

[28]  Venkatesh Kodur,et al.  Design equation for predicting fire resistance of reinforced concrete beams , 2011 .

[29]  Ulf Wickström,et al.  A very simple method for estimating temperaturein fire exposed concrete structures , 1986 .