Beam web openings to AISC

Tekla Structural Designer
2021
Tekla Structural Designer

Beam web openings to AISC

Web Opening design limitations

  • Simple beams only (single span, pin ended). Although web openings can be defined on multi-span beams design is beyond scope.
    • Cantilevers are excluded.
    • Curved beams are excluded.
    • Haunched and tapered members are excluded.
  • Section type: rolled symmetrical compact I sections.
    • Plated sections are excluded.
  • Steel yield strength is limited to 65 ksi
  • Web opening placement and sizes: Opening depth is limited to 70 percent of beam depth. There are also two control parameters which dictate the dimensions of the opening, one being the aspect ratio, ao/ho, of the opening and the other being the opening parameter po. Both should meet the required limits.
  • Multiple openings. Checks are performed to ensure that openings are spaced far enough apart so that design expressions for individual openings may be used.
  • Openings cannot be placed closer than the section height to a support.
  • Openings can be defined as rectangular or circular; circular openings are designed as equivalent rectangular openings.
  • Openings can be reinforced on one side or both sides but always top or bottom, but no checks are performed on the reinforcement and its welds.
  • No concentrated loads should be placed above an opening. If there is a point load above the opening then that combination gets a Beyond Scope status, (but only if the concentrated load is greater than 25% of the shear strength of the two tee sections).
  • The nearest concentrated load should be placed at least d/2 from the edge of the opening.
  • A check is performed to determine whether bearing stiffeners are necessary, if so these are not designed but a warning is shown.
  • ASD design i.e. LRFD only.
Note: For details of the web opening design checks performed see Web openings (Beams: AISC 360)
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