THE ULTIMATE STRENGTH OF BIAXIALLY RESTRAINED COLUMNS

A general method for the calculation of ultimate loads of biaxially restrained columns is presented. The column length is subdivided into a number of segments and conditions of equilibrium are satisfied at the nodal points. The solution is based on the well-known Netwon-Raphson iterative procedure for systems of non-linear equations. An efficient procedure for the evaluation of the jacobian matrix involved is outlined. The moment-thrust-curvature relations required are evaluated by a completely general procedure adopted by the authors in an earlier paper making possible the ultimate load analysis of columns of a wide variety of cross-sections, including bare steel, reinforced concrete and composite steel-concrete sections. It is shown that for columns loaded in symmetrical bending in both the flexural planes, accurate results can be obtained by taking as few AS Eight subdivisions along the column length. However, for columns in double curvature bending in both the flexural planes, excessively large errors on the unsafe side may occur in the estimated ultimate load if the column length is not subdivided into a sufficient number of segments. It is found that with 16-20 subdivisions the errors in estimating ultimate loads can be restricted to around 5%. The method is shown to give good correlation with experimental results for eight h shaped steel columns with biaxial end restraints. In another comparison, good agreement with test results is obtained with respect to the ultimate loads as well as deflexions of nine pin-ended composite columns with biaxial eccentricities. (A). /TRRL/

Media Info

  • Features: Figures; Tables;
  • Pagination: p. 41-58
  • Serial:
    • Volume: 61

Subject/Index Terms

Filing Info

  • Accession Number: 00137498
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: ITRD, TRIS
  • Created Date: Oct 6 1976 12:00AM