F2. Flexure (Beams: AISC 360)

Tekla Structural Designer
2021
Tekla Structural Designer

F2. Flexure (Beams: AISC 360)

The member is assessed for Flexure in accordance with Section F2 to F10 (as appropriate).

The following checks are potentially required:

About the x axis - within the LTB braced length

  • Yielding

  • Compression flange local buckling

  • Web local buckling

  • Local buckling

  • Lateral torsional buckling (only required for I and C sections)

About the y axis in the LTB braced length

  • Yielding

  • Flange local buckling

  • Web local buckling

  • Local buckling

You can switch off the lateral torsional buckling checks for any unbraced length by indicating the length is continuously braced. If you use this option you must be able to provide justification that the unbraced length is adequately braced against lateral torsional buckling.

When the checks are required Tekla Structural Designer assumes a top flange (but not bottom flange) brace is provided at the position of each incoming beam. You can add or remove these braces if they don't reflect the actual brace provided by the incoming section. Each unbraced length which is not defined as being continuously braced is then checked in accordance with Section F2.

Plated beams only

The following additional checks apply about the x axis:

  • Compression flange yielding

  • Tension flange yielding

The approach to evaluating the web plastification factors, Rpc and Rpt in Section F4.2 and F4.4 of 360-10, has been adopted for 360-05 also i.e. the ratio Iyc/Iy is considered as well as hc/tw but note the following:

  • under 360-05, Iyc is taken as the minimum inertia about the y axis of top and bottom flange (regardless which flange is in compression)

  • under 360-10, Iyc is taken as the inertia about the y axis of the compression flange being considered

For flange local buckling about the y axis Equation F6-2 is used for both double and single symmetric sections, but in the latter case the more slender of the two flanges is assessed i.e. the higher λ value will be used.

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