W21X57 Steel Beam — Section Properties
Dimensions
| Property | Value | Unit |
|---|---|---|
| Depth (d) | 21.10 | in (535.9 mm) |
| Flange Width (bf) | 6.56 | in (166.6 mm) |
| Flange Thickness (tf) | 0.65 | in |
| Web Thickness (tw) | 0.41 | in |
| Area (A) | 16.70 | in² (107.7 cm²) |
| Weight | 57 | lb/ft (85 kg/m) |
Elastic Section Properties
| Property | Strong Axis (X-X) | Weak Axis (Y-Y) | Unit |
|---|---|---|---|
| Moment of Inertia (I) | 1,170 | 30.60 | in⁴ |
| Elastic Section Modulus (S) | 111 | 9.35 | in³ |
| Plastic Section Modulus (Z) | 129 | 14.80 | in³ |
| Radius of Gyration (r) | 8.36 | 1.35 | in |
Torsional Properties
| Property | Value | Unit |
|---|---|---|
| Torsional Constant (J) | 1.77 | in⁴ |
| Warping Constant (Cw) | 3,190 | in⁶ |
| Distance Between Flange Centroids (ho) | 20.50 | in |
| Effective Radius (rts) | 1.68 | in |
Design Resources
- Beam Capacity Calculator — Check W21X57 for your span and loads
- Column Capacity Calculator — Check W21X57 as a column
- Section Properties Database — Compare with other sections
- Steel Beam Sizes Reference — Full W-shape dimension table
- Steel Grades Reference — A992/A572 material properties
Frequently Asked Questions
What is the weight of a W21X57 beam? 57 lb/ft (85 kg/m). A 40-ft length weighs approximately 2,280 lbs.
What is the section modulus of W21X57? Sx = 111 in³ (strong axis) and Sy = 9.3 in³ (weak axis). The plastic section modulus Zx = 129 in³ and Zy = 14.8 in³.
What steel grade is standard for W21X57? Typically ASTM A992 (Fy = 50 ksi, Fu = 65 ksi) for W-shapes. Also available in A572 Grade 50 or A36. Verify with mill certificate.
What is the moment of inertia of W21X57? Ix = 1170 in⁴ about the strong axis and Iy = 30.6 in⁴ about the weak axis. The radius of gyration is rx = 8.36 in and ry = 1.35 in.
Related Pages
- Steel Beam Sizes Reference
- Beam Capacity Calculator
- Column Capacity Calculator
- Section Properties Database
Educational reference only. Verify all section properties against the current AISC Manual and mill certificates before design. Results are PRELIMINARY — NOT FOR CONSTRUCTION.