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?

Symbols

b_f : width of the flange, in. (mm)
E : Modulus of elasticity of steel = 29,000 ksi (200 000 MPa)
F_y : Specified minimum yield stress of the type of steel being used, ksi
h : Distance as defined in AISC 360-16 Table 4.1b
L_b : Length between points that are either braced against lateral displacement of the compression flange or braced against twist of the cross-section, in. (mm)
L_p : The limiting laterally unbraced length for the limit state of yielding, in. (mm)
L_r : The limiting unbraced length for the limit state of inelastic lateral-torsional buckling, in. (mm),
M_n : The nominal flexural strength
M_p : Plastic bending moment
t_f : thickness of the flange, in. (mm)
Z_x = Plastic section modulus about the x-axis, in.³ (mm³)
λ_p : Limiting slenderness for a compact flange, defined in Table B4.1b
λ_r : Limiting slenderness for a noncompact flange, defined in Table B4.1b

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

• When L_b ≤ L_p

• When L_p < L_b ≤ L_r

• When L_b > L_r

Compression Flange Local Buckling Limit State

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

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

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