Design of Concrete Frames For Two Failure Stages


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Title: Design of Concrete Frames For Two Failure Stages

Author(s): Herbert A. Sawyer, Jr.

Publication: Special Publication

Volume: 12


Appears on pages(s): 405-437


Date: 1/1/1965

With discussion by M. Z. Cohn, Milik Tichy and Milos Vorlicek, and Herbert A. Sawyer, Jr. It is proposed that statically indeterminate beams and frames be designed for suitably low probabilities of failure for two failure stages. One stage would be wide cracking, using an elastic analyses for stresses at a section and for distribution of moments. The other stage would be crushing-spalling, for which the conventionalultimate strength analysis wouldbe used at sections, and an analysis based on a bilinear moment-curvature relationship and plasticity factors would be used for the distribution of moments. The required moment-curvature relationships and plasticity factors are derived and presented quantitatively. The design procedure based on these analyses is outlined, and revisions in present load factors, based on both a critical re-examination of simplebeam test results and the special characteristics of bilinear analysis, are recommended. Finally, the quantitative evidence available on the validity of the proposed method from the experimental investigations of continuous beams by Glanville and Thomas, Mattock, Ray and Nilsen, and Petcu and Cohn, is presented. Agreement is good within the limited range of these investigations.