# Doubly Symmetric I-Shaped Members with Compact Webs and Noncompact or Slender Flanges Bent About Their Major Axis per AISC 360-16 with ideCAD

How does ideCAD calculate the flexural strength for doubly symmetric I-shaped members with compact webs and noncompact or slender flanges according to AISC 360-16?

• The flexural strength of steel elements is calculated automatically according to AISC 360-16.

• The nominal flexural strength limit states yielding, and lateral-torsional buckling are controlled automatically according to AISC 360-16.

• For design members for flexure, sections are automatically classified as compact, non-compact, or slender-element sections, according to AISC 360-16.

Symbols

bf : width of the flange, in. (mm)
E : Modulus of elasticity of steel = 29,000 ksi (200 000 MPa)
Fy : Specified minimum yield stress of the type of steel being used, ksi
h : Distance as defined in AISC 360-16 Table 4.1b
Lb : Length between points that are either braced against lateral displacement of the compression flange or braced against twist of the cross-section, in. (mm)
Lp : The limiting laterally unbraced length for the limit state of yielding, in. (mm)
Lr : The limiting unbraced length for the limit state of inelastic lateral-torsional buckling, in. (mm),
Mn : The nominal flexural strength
Mp : Plastic bending moment
tf : thickness of the flange, in. (mm)
Zx = Plastic section modulus about the x-axis, in.3 (mm3)
λp : Limiting slenderness for a compact flange, defined in Table B4.1b
λr : Limiting slenderness for a noncompact flange, defined in Table B4.1b

The nominal flexural strength, Mn, should be the lower value obtained according to the limit states of lateral-torsional buckling and compression flange local buckling.

Lateral Torsional Buckling Limit State

The nominal flexural strength, Mn, for the lateral-torsional buckling limit state, is explained in the section.

• When Lb ≤ Lp

• When Lp < Lb ≤ Lr

• When LbLr

Compression Flange Local Buckling Limit State

The nominal flexural strength, Mn, for sections with noncompact flanges;

The nominal flexural strength, Mn, for sections with slender flanges;

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