Failure of Lightly Reinforced Concrete Members under Fire. I: Analytical Modeling

This paper is concerned with the failure of lightly reinforced concrete members under fire conditions, with particular emphasis given to the catenary action arising from axial restraint at the supports and the ensuing rupture of the reinforcement. The relevance of this work stems from the need to make a fundamental step toward understanding the conditions that influence the failure of a steel-decked composite floor slab, which is shown to become effectively lightly reinforced at elevated temperature. A new analytical model is proposed for lightly reinforced members subject to axial restraint, which accounts for the compressive arch and tensile catenary stages, bond-slip, yielding, and rupture of the steel reinforcement as well as the effect of elevated temperature. The versatility of the proposed model and the conditions which govern its validity are illustrated in this paper through comparisons with detailed computations based on nonlinear finite element analysis. The companion paper utilizes the proposed analytical model to perform a parametric investigation into the factors influencing the failure of lightly reinforced members, and to highlight key implications for structural fire resistance design.

[1]  Asif Usmani,et al.  A structural analysis of the first Cardington test , 2001 .

[2]  Amr S. Elnashai,et al.  An integrated adaptive environment for fire and explosion analysis of steel frames — Part II:: verification and application , 2000 .

[3]  Bassam A. Izzuddin,et al.  Efficient nonlinear analysis of elasto-plastic 3D R/C frames using adaptive techniques , 2000 .

[4]  A. Y. Elghazouli,et al.  Analytical assessment of the structural performance of composite floors subject to compartment fires , 2001 .

[5]  Amr S. Elnashai,et al.  ADAPTIVE SPACE FRAME ANALYSIS. PART II: A DISTRIBUTED PLASTICITY APPROACH. , 1993 .

[6]  Colin Bailey,et al.  The behaviour of full-scale steel-framed buildings subjected to compartment fires , 1999 .

[7]  Yong Wang,et al.  The behaviour of steel frames subject to fire , 1995 .

[8]  T. Paulay,et al.  Reinforced Concrete Structures , 1975 .

[9]  Alberto Carpinteri,et al.  Minimum reinforcement in high strength concrete , 1990 .

[10]  B. Izzuddin,et al.  Nonlinear dynamic analysis of framed structures , 1990 .

[11]  Amr S. Elnashai,et al.  Application of Adaptive Analysis to Reinforced Concrete Frames , 1994 .

[12]  Bassam A. Izzuddin,et al.  Lessons from a full-scale fire test , 2002 .

[13]  A. Y. Elghazouli,et al.  Response of idealised composite beam–slab systems under fire conditions , 2000 .

[14]  P. J. Dowling,et al.  An integrated adaptive environment for fire and explosion analysis of steel frames — Part I:: analytical models , 2000 .

[15]  C. G. Bailey,et al.  The structural behaviour of steel frames with composite floorslabs subject to fire: Part 1: Theory , 2000 .

[16]  M. A O'Connor,et al.  Behaviour of a Multi-storey Steel Framed Building Subjected to Fire Attack , 1998 .

[17]  A. Y. Elghazouli,et al.  Failure of lightly reinforced concrete members under fire. II: Parametric studies and design considerations , 2004 .

[18]  Amr S. Elnashai,et al.  Eulerian formulation for large-displacement analysis of space frames , 1993 .