A reappraisal of the nominal curvature method in the fire design of reinforced concrete columns

A reappraisal of the method based on nominal curvature for designing reinforced concrete columns in fire is proposed, with the focus on the validation of an alternative and widely accepted way of applying the method, which differs from the current provisions of EN 1992-1-2. To this end, a systematic comparison between experimental and numerical results is carried out on a database consisting of 74 columns tested in different laboratories. The comparison shows that the method based on nominal curvature yields conservative estimates of the time to failure. Moreover, the numerical results obtained are reasonably close to those obtained by means of finite element analysis. By contrast, if the method is applied in combination with the simplified methods introduced in EN 1992-1-2, the numerical results are not conservative, with a significant overestimation of the bearing capacity of the columns, and of the time to failure, mainly because of the overestimation of the stiffness by the simplified methods.

[1]  Yao Yao,et al.  Fire resistance of reinforced concrete columns. , 2002 .

[2]  Thomas Gernay,et al.  Fire resistance and burnout resistance of reinforced concrete columns , 2019, Fire Safety Journal.

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

[4]  Patrick Bamonte,et al.  Reinforced concrete columns exposed to standard fire: Comparison among different constitutive models for concrete at high temperature , 2015 .

[5]  Z. Bažant,et al.  Stability of Structures: Elastic, Inelastic, Fracture and Damage Theories , 2010 .

[6]  Luc Taerwe,et al.  fib Bulletin 46. Fire design of concrete structures – structural behaviour and assessment , 2008 .

[7]  Bernd Weissmuller.  Stability Of Structures Elastic Inelastic Fracture And Damage Theories , 2016 .

[8]  Jean-Marc Franssen,et al.  Calculation Method for Design of Reinforced Concrete Columns under Fire Conditions , 1999 .

[9]  T. T. Lie,et al.  METHOD TO CALCULATE THE FIRE RESISTANCE OF CIRCULAR REINFORCED CONCRETE COLUMNS , 1991 .

[10]  T. T. Lie,et al.  Method to Calculate the Fire Resistance of Reinforced Concrete Columns With Rectangular Cross Section , 1993 .

[11]  Guido Morgenthal,et al.  Identification of the thermal properties of concrete for the temperature calculation of concrete slabs and columns subjected to a standard fire—Methodology and proposal for simplified formulations , 2017 .

[12]  J. Zehfuß,et al.  Neuer Ansatz der thermischen Leitfähigkeit von Beton für die Brandschutzbemessung in Eurocode 2 , 2019, Bautechnik.

[13]  Gert Heshe,et al.  DS/ENV 1992-1-1 NAD. National Application Document for Eurocode 2: Design of Concrete Structures, Part 1-1: General Rules and Rules for Buildings , 1993 .

[14]  Guido Morgenthal,et al.  Extension of the Zone Method of Eurocode 2 for reinforced concrete columns subjected to standard fire , 2016 .

[15]  Patrick Bamonte,et al.  Today's concretes exposed to fire - test results and sectional analysis , 2008 .