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Special Moment Frames (SMF) per AISC 341-16 §E3

How does ideCAD control special moment frame requirements according to AISC 341-16?

  • Special Moment Frame members are automatically designed in accordance with AISC 341-16 E3.


Fy = Specified minimum yield stress
Ry = Ratio of the expected yield stress to the specified minimum yield stress, Fy
Lb = Length between points which are either braced against lateral displacement of compression flange or braced against twist of the cross-section, in. (mm)
ΣMpb = sum of the projections of the expected flexural strengths of the beams at the plastic hinge locations to the column centerline.
ΣMpc = sum of the projections of the nominal flexural strengths of the columns (including haunches where used) above and below the joint to the beam centerline with a reduction for the axial force in the column.
ry = Radius of gyration about y-axis, in. (mm)
E= Modulus of elasticity of steel = 29,000 ksi (200 000 MPa)

Basis of Design

Special Moment Frames should be designed according to AISC 341-16, in which structural elements are expected to provide significant inelastic deformation capacity through flexural yielding of SMF beams and limited yielding of column panel zones.

System Requirements

Moment Ratio

Columns must be stronger than beams to prevent brittle collapse, except for the intended mechanism.

Stability Bracing of Beams

Beams should be braced to provide the requirements for highly ductile members in Section D1.2b.

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