# AISC ASD (9th,1989)

AISC ASD (9th,1989) - an American national standard "Specification for Structural Steel Buildings" Allowable Stress Design and Plastic Design, released in July 1, 1989.

This Standard implements checks for the design of members for tension, compression, bending, shear and combined.

Note: Checks are performed for I-beams, Channels, Tee, Circular and Rectangular tubes, Circular and Rectangular bars.

To add the standard execute Standards - Main - AISC - AISC ASD 89 (9th, 1989) from the ribbon:

Press to Set Standard Custom Settings

To see what elements are not verified for all checks or bending checks according to AISC ASD 1989 press Preview not supported elements.

Press to set Section Build Type (rolled or built up).

Lateral-torsional buckling modification factor (Cb) can be calculated based on moment diagram of beam member or defined manually. By default user defined option is used and Cb is set to 1 (conservative):

Where M1 is the smaller and M2 the larger bending moment at the ends of the unbraced length, taken about the strong axis of the member.

Press to set Cb manually.

By default clear distance between transverse stiffeners are set to torsional member length. (It means there are no transverse stiffeners). Stiffener distance is used to calculate allowable shear stress:

According to the calculation procedure, Beam Length for Y and Z direction is required. Data from Beam Member Finder is used automatically. If beam members are not recognized press .

Standard uses material data (Yield/Tensile) in calculations. Wizard checks if the values are defined for all materials.

Calculate asymmetric shapes as symmetric - minimum sizes of walls/flanges will be used to calculate cross-section properties (area, moments of inertia etc.). Option works within the current standard.

Note: Execute Model - Properties - Map Shapes as Symmetric from the tree to transform asymmetric I-beams, Channels or Rectangular tubes to symmetric for the full project.

It is possible to take into account second order effects (see explanation in AISC ASD 89 , Appendix 8):

AISC ASD 89 can be used in a combination with API RP 2A-WSD (21st, 2007) standard. Set the option Use API 2A WSD for tubular shapes checked to use the standard for circular tubes. Press to define settings.

Note: If the API 2A WSD is included - 3 standards will be created:

- AISC ASD 89 - all supported shapes are calculated according to AISC ASD 89;
- API RP 2A-WSD - circular tubes are calculated according to API RP 2A-WSD;
- AISC and API - combined standard where results for circular tubes are taken from API RP 2A-WSD and results for other supported shapes - according to AISC ASD 89.

To verify the model create a table for Overall check (if API WSD is included then for the check of AISC and API standard):

All Checks have Utilization Factor parameter = (Force, Moment, etc.) / Design Strength. It should be below one (<1) then the check passes.

The value 12345678 is used when the calculations cannot be performed due to geometrical limitations or calculations are out of scope.