W30x391 Section Properties
Complete geometric properties for the W30x391 (Wide Flange) per AISC Steel Construction Manual, 16th Edition. This section weighs 391.0 lb/ft. Wide flange shapes are the most commonly used structural steel members in building construction. They have an I-shaped cross section with parallel flanges and are designated by their nominal depth and weight per foot.
| Property | Value | Unit |
|---|---|---|
| Depth | 33.2 | in |
| Flange Width | 15.6 | in |
| Flange Thickness | 2.44 | in |
| Web Thickness | 1.36 | in |
| Cross-Sectional Area | 115 | in² |
| Moment of Inertia (x-axis) | 20700 | in⁴ |
| Moment of Inertia (y-axis) | 1550 | in⁴ |
| Elastic Section Modulus (x-axis) | 1250 | in³ |
| Elastic Section Modulus (y-axis) | 199 | in³ |
| Plastic Section Modulus (x-axis) | 1450 | in³ |
| Plastic Section Modulus (y-axis) | 308 | in³ |
| Radius of Gyration (x-axis) | 13.4 | in |
| Radius of Gyration (y-axis) | 3.67 | in |
| Torsional Constant | 121 | in⁴ |
About Wide Flange Shapes
Wide flange shapes are the most commonly used structural steel members in building construction. They have an I-shaped cross section with parallel flanges and are designated by their nominal depth and weight per foot.
How to Use This Data
The properties listed above are used in structural engineering calculations including:
- Moment of Inertia (I) — used to calculate deflection and stiffness. Higher I = less deflection under load.
- Section Modulus (S) — used to calculate bending stress. σ = M/S, where M is the bending moment.
- Plastic Section Modulus (Z) — used in LRFD design to calculate plastic moment capacity. Mp = Fy × Z.
- Radius of Gyration (r) — used in column buckling calculations. Higher r = more resistance to buckling.
- Torsional Constant (J) — used to calculate torsional resistance and lateral-torsional buckling.
- Area (A) — used to calculate axial capacity and self-weight.
Use our interactive Section Properties Calculator to compare shapes, calculate composite sections, or look up any AISC shape. For beam design, try our Beam Calculator or Wood Beam Designer.
Data source: AISC Steel Construction Manual, 16th Edition. All dimensions in inches, areas in square inches, moments of inertia in in⁴, section moduli in in³. Values are for design reference — always verify against the current edition of the AISC Manual for final design.
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