In this paper, the ultimate strength of deep girders is investigated from the view point of a safe design against lateral instability of these members. First, theoretical analysis is made on a deep girder subjected to bending moment around strong-axis of the girder and axial thrust acting in the plane of the web. Analysis based on the flow theory of plasticity is performed by considering the elasto-plastic behavior of the flange and the web with the effect of strain reversal, and a successive step by step method is applied to find out the maximum bending moment which the girder can carry at the ultimate state. A computer program is developed for the analysis, and the numerical calculations are made to investigate the effect of the axial thrust, span of the girders, cross sectional properties, rigidity of web stiffeners and the magnitude of initial deflections on the ultimate strength of deep girders. Experimental tests are also carried out on model girders of various length of span. Extensive measurements and observations are made on the lateral deflections of flange and web, as well as their curvatures so as to determine experimentally the equivalent span of the girders. Comparisons are made between the test results and the theoretical predictions on the ultimate strength of the girders, and a fairly close agreement is found. A survey is made on the conventional scantlings of center girders, transverses, horizontal girders and longitudinals of large tankers and ore carriers built in the past years to examine the ultimate strength of these members. Finally, an approximate design formula is suggested on the minimum breadth of flange of the girders and the longitudinals, necessary for assuring the ultimate strength factor up to a certain prescribed value in terms of their fully plastic moment.

  • Corporate Authors:

    Society of Naval Architects of Japan

    23 Shiba-kotohiracho, Minato-ku
    Tokyo 135,   Japan 
  • Authors:
    • Nitta, A
  • Publication Date: 1972

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Filing Info

  • Accession Number: 00035171
  • Record Type: Publication
  • Source Agency: Society of Naval Architects of Japan
  • Files: TRIS
  • Created Date: Oct 27 1973 12:00AM