EXPERIMENTAL AND COMPUTATIONAL INVESTIGATION OF FIRE BEHAVIOR OF RESTRAINED REINFORCED CONCRETE COLUMNS - PART II

Yıl 2017, Cilt: 18 Sayı: 2, 121 - 136, 15.12.2017

Ataman Haksever

Öz

In
the eighties the work was particularly focused in SFB (SonderForschungsBereich: A special fire research activity for
structural elements in Braunschweig Technical University, 1971-1986) on
the development of a universal material model for normal concretes in case of
fire. Through a comprehensive mathematical description of  the rheological phenomena at elevated
temperatures, the relaxation behavior of restrained col­umns could be
successfully predicted. It aimed at clarifying the difference, which took place
between the deformation behavior as well as restraint forces of calculated and
measured reinforced concrete columns (RFC) under fire conditions. Such a
material model was developed, in fact, through close cooperation of subprojects
A and B3 of SFB.

Naturally,
the use of such material model requires an immense computational treatment.
Theoretical studies have shown, however, that this is worthwhile, because only
by this process the fire behavior of structural concrete elements can be taken
into account satisfactorily. It should be stressed here that a material model
can gain confidence only if it has been tested successfully under different
boundary conditions. In particular, the model must apply for the assessment of
the fire behavior of structural elements in large scale.

In
this regard relaxation tests on reinforced concrete columns under different
boundary conditions have been carried out in the special furnace of SFB. The
heating of the reinforced concrete columns have been made with respect to ISO830-fire
as well as to a simulated natural fire condition. The following sections
describe the tests and also their theoretical investigation.

Anahtar Kelimeler

Structural fire safety, reinforced concrete columns, fire resistance, relaxation, fire behavior

Kaynakça

• Anderberg, Y. Fire-Exposed Hyperstatic Concrete Structures- A Testal and Theoretical Study. Div. of Structural- Mechn. And Concrete Constr., Inst. of Techn., Lund, 1976.
• Anderberg, Y. Stress and Deformation charesterisctics of Concrete in high Temperatures. RILEM-Committee 44-PHT, Febr. 1983.
• António José P. Moura Correia, João Paulo C. Rodrigues. Fire resistance of steel columns with restrained thermal elongation. Fire Safety Journal, Volume 50, May 2012, Pages 1-11.
• Bazant, Z.P.; Chern, J.C. Concrete Creep at Variable Humidity: Constructive Law and Mechanism. Mat. et Con¬str., Vol.18, No.103, 1/20, 1985.
• David Lange, Johan Sjöström. Mechanical response of a partially restrained column exposed to localized fires. Fire Safety Journal, Volume 67, July 2014, Pages 82-95.
• DIN V ENV 1992-1-2 Eurocode 2 – Planung von Stahlbeton- und Spannbeton-tragwerken, Teil 1-2. Allgemeine Regeln – Tragwerksbemessung für den Brandfall, (Design of constructions for fire exposure), (1997).
• DIN 4102 – Brandverhalten von Baustoffen und Bauteilen (Fire behavior of building materials and structural elements) Teile 1-3, Teile 5-7, and Teil 4., DIN Deutsches Institut für Normung E.V., Beuth Verlag, Berlin, (1981)
• Haksever, A. Zum Relaxationsverhalten von Stahlbetonstützen im Brandfall. SFB Jahresbericht 1981-1983, Teil I (On the relaxation behavior of reinforced concrete columns in case of fire, SFB, Report) Technische Universität Braunschweig.
• Haksever, A. Relaxationsverhalten von Stahlbetontragwerke im Brandfall. SFB Jahresbericht 1978-1980, Teil I (Relaxation behaviour of reinforced concrete structures), Technische Universität Braunschweig.
• Haksever, A. Mathematische Modellierung des Verformungsverhaltens von Festbe-tone unter Brandbeanspruchung. SFB Jahresbericht 1984-1986, Teil I (Mathematical description of deformation behavior hard concrete), Technische Universität Braunsch-weig.
• Haksever, A. Gesamtverformung der Großbeton-Probekörper im Brandfall. SFB Jahresbericht 1984-1986, Teil I (Total deformation large scale specimens in case of fire., SFB, Report 1984-1986, Part I), Technische Universität Braunschweig.
• Anderberg, Y. Fire-Exposed Hyperstatic Concrete Structures- A Testal and Theoretical Study. Div. of Struct. Mechn. And Concrete Constr., Inst. of Techn., Lund, 1976.
• Anderberg, Y. Stress and Deformation charesterisctics of Concrete in high tempera¬tures. RILEM-Committee 44-PHT, Febr. 1983.
• António José P. Moura Correia, João Paulo C. Rodrigues. Fire resistance of steel columns with restrained thermal elongation
• International Organization for Standardization ISO Central Secretariat. Chemin de Blandonnet 8, CP 401. 1214 Vernier, Geneva,Switzerland
• I. Cabrita Neves, J.C. Valente, J.P. Correia Rodrigues. Thermal restraint and fire resistance of columns. Fire Safety Journal, Volume 37, Issue 8, November 2002, Pages 753-771.
• Kang-Hai Tan, Truong-Thang Nguyen. Structural responses of (RFC) subjected to uniaxial bending and restraint at elevated temperatures. Fire Safety Journal, Volume 60, August 2013, Pages 1-13.
• Klingsch, W., Ttraglastberechnung instationär thermisch belasteter Stahlbeton-Druck-glieder (Load bearing calculation of reinforced concrete compression elements under instationary thermic loading).,Diss., Technishe Universitat Braunschweig, 1975.
• P. Bamonte, F. Lo Monte. Reinforced concrete columns exposed to standard fire: Comparison among different constitutive models for concrete at high temperature. Fire Safety Journal, Volume 71, January 2015, Pages 310-323.
• Schneider, U. Behaviour of Concrete at High Temperatures. Deutscher Ausschuss für Stahlbeton, Heft 337, Verlag W. Ernst und Sohn, Berlin, 1982.
• Schneider, U. Creep and Relaxation of Concrete under High Temperatures (in German). Habilitation, Technische Universität Braunschweig, 1979.
• SFB 148. “Sonderforschungsbereich 148; Brandverhalten von Bauteilen” (A special research field Nr. 148; Fire behavior of structural elements). Subproject A: Fire behavior of structural elements Subproject B3: Material behavior of structural elements at elevated temperatures. Technisce Universität Braunschweig, Germany. (1971-1986)
• Truong-Thang Nguyen, , Kang Hai Tan. Structural responses of (RFC) subjected to uniaxial bending and restraint at elevated temperatures. Fire Safety Journal, Volume 69, October 2014, Pages 136–146.