The Collapse of Reinforced Concrete Beams


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Title: The Collapse of Reinforced Concrete Beams

Author(s): Peter R. Barnard

Publication: Special Publication

Volume: 12


Appears on pages(s): 501-520


Date: 1/1/1965

With discussion by Leonard G. Tulin and Kurt H. Gerstle, Ralph M. Richard and Stanley D. Hansen, and Peter R. Barnard. The purpose of this paper is to explain, in the light of recent research into the concrete stress-strain relationship in compression, the flexural behavior of statically indeterminate reinforced conrete beams when loaded to collapse. Based on the concept of concrete as a strain-softening material, it is shown that a length of a beam can continue to rotate when moment is falling off and that rupture will not occur unless the energy balance in the beam ceases to be satisfied. In a comparison between the inelastic behavior of structural steel and reinforced concrete beams, it is shownthat in the latter there is a distinct maximum load which such a beam can withstand; that hinging regions tend to contract rather than spread as in steel; that it is possible for some regions of a beam to be falling off in moment while the total load on the beam is increasing; and that moment redistribution occurs through falloff in moment at some sections as well as through inelastic action. Finally, the possible development of true collapse methods for the analysis or design of indeterminate reinforced concrete beams is discussed.