W18×211 Steel Beam
A W18×211 is a wide flange steel beam 20.7 inches deep with 11.6-inch flanges, weighing 211 pounds per foot. In ASTM A992 steel (Fy = 50 ksi) it has a design bending strength of 1,838 kip-ft (LRFD) when its compression flange is braced, and a design shear strength of 658 kips.
Design a W18×211 beam Opens a 32 ft span in the free beam designer.
W18×211 dimensions
| Dimension | Value |
|---|---|
| Depth, d | 20.7 in |
| Flange width, bf | 11.6 in |
| Flange thickness, tf | 1.91 in |
| Web thickness, tw | 1.06 in |
| Distance to web toe of fillet, kdes | 2.31 in |
| Distance between flange centroids, ho | 18.79 in |
| Cross-sectional area, A | 62.1 in2 |
| Weight | 211 lb/ft |
Dimensions are AISC design values. Detailing dimensions are rounded to the nearest 1/16 in.
W18×211 section properties
| Property | Strong axis (x) | Weak axis (y) |
|---|---|---|
| Moment of inertia, I | 4330 in4 | 493 in4 |
| Elastic section modulus, S | 419 in3 | 85.3 in3 |
| Plastic section modulus, Z | 490 in3 | 132 in3 |
| Radius of gyration, r | 8.35 in | 2.82 in |
| Torsion and slenderness | Value |
|---|---|
| Torsional constant, J | 58.6 in4 |
| Warping constant, Cw | 43400 in6 |
| Effective radius of gyration, rts | 3.32 in |
| Flange slenderness, bf/2tf | 3.02 |
| Web slenderness, h/tw | 15.1 |
W18×211 bending and shear strength
For ASTM A992 steel (Fy = 50 ksi, E = 29,000 ksi) per AISC 360-16. Its flanges and web are compact for bending, so with its compression flange braced it reaches its full plastic moment.
| Strength | LRFD | ASD |
|---|---|---|
| Bending, compression flange braced | φMn = 1,838 kip-ft | Mn/Ω = 1,223 kip-ft |
| Shear | φVn = 658 kips | Vn/Ω = 439 kips |
If the compression flange isn't braced, the beam can buckle sideways before it yields. Up to Lp = 10.0 ft between braces it keeps its full strength; past Lr = 55.7 ft it buckles elastically. With uniform moment between braces (Cb = 1.0):
| Unbraced length, Lb | φMn (LRFD) | Mn/Ω (ASD) |
|---|---|---|
| Braced | 1,838 kip-ft | 1,223 kip-ft |
| 10.0 ft (Lp) | 1,838 kip-ft | 1,223 kip-ft |
| 10 ft (Lp) | 1,837 kip-ft | 1,222 kip-ft |
| 20 ft | 1,676 kip-ft | 1,115 kip-ft |
| 30 ft | 1,515 kip-ft | 1,008 kip-ft |
| 40 ft | 1,353 kip-ft | 900 kip-ft |
| 50 ft | 1,192 kip-ft | 793 kip-ft |
| 55.7 ft (Lr) | 1,100 kip-ft | 732 kip-ft |
| 60 ft | 1,018 kip-ft | 677 kip-ft |
| 70 ft | 869 kip-ft | 578 kip-ft |
| 80 ft | 758 kip-ft | 504 kip-ft |
| 90 ft | 672 kip-ft | 447 kip-ft |
| 100 ft | 604 kip-ft | 402 kip-ft |
| 110 ft | 548 kip-ft | 365 kip-ft |
A beam with a uniform load between braces has Cb above 1.0 (1.14 for a simple span braced only at its ends), so these values are conservative. The beam designer works out Cb for every segment between braces.
W18×211 load table by span
The largest uniform load a simply supported W18×211 can carry, in kips per foot, with its compression flange braced along its length (by a floor or roof deck, for example). The loads include the beam's own weight of 0.211 kips per foot.
| Span | Factored load (LRFD) | Allowable load (ASD) | Load at span/360 | Load at span/240 |
|---|---|---|---|---|
| 10 ft | 131.7* | 87.8* | 186.0 | 279.0 |
| 12 ft | 102.1 | 67.9 | 107.7 | 161.5 |
| 14 ft | 75.0 | 49.9 | 67.8 | 101.7 |
| 16 ft | 57.4 | 38.2 | 45.4 | 68.1 |
| 18 ft | 45.4 | 30.2 | 31.9 | 47.8 |
| 20 ft | 36.8 | 24.5 | 23.3 | 34.9 |
| 22 ft | 30.4 | 20.2 | 17.5 | 26.2 |
| 24 ft | 25.5 | 17.0 | 13.5 | 20.2 |
| 26 ft | 21.7 | 14.5 | 10.6 | 15.9 |
| 28 ft | 18.8 | 12.5 | 8.47 | 12.7 |
| 30 ft | 16.3 | 10.9 | 6.89 | 10.3 |
| 32 ft | 14.4 | 9.55 | 5.68 | 8.52 |
| 34 ft | 12.7 | 8.46 | 4.73 | 7.10 |
| 36 ft | 11.3 | 7.55 | 3.99 | 5.98 |
| 38 ft | 10.2 | 6.77 | 3.39 | 5.09 |
| 40 ft | 9.19 | 6.11 | 2.91 | 4.36 |
| 42 ft | 8.33 | 5.54 | 2.51 | 3.77 |
| 44 ft | 7.59 | 5.05 | 2.18 | 3.28 |
| 46 ft | 6.95 | 4.62 | 1.91 | 2.87 |
| 48 ft | 6.38 | 4.24 | 1.68 | 2.52 |
| 50 ft | 5.88 | 3.91 | 1.49 | 2.23 |
| 52 ft | 5.44 | 3.62 | 1.32 | 1.98 |
- Factored and allowable loads are limited by bending, or by shear where marked *.
- The deflection columns are the service loads that make the beam sag span/360 or span/240. Compare span/360 with the live load alone and span/240 with dead plus live load, the usual floor limits in IBC Table 1604.3.
Reading the table
At a 32 ft span, a W18×211 carries a factored load of 14.4 kips per foot (LRFD) or an allowable load of 9.55 kips per foot (ASD). A live load of 5.68 kips per foot would deflect it span/360, which is 1.07 in. The beam works if the factored load is under the first number and the live and total loads are under the deflection numbers. For other spans, supports or loads, open it in the beam designer, or follow the steel beam design guide to check one by hand.
W18×211 questions
What does W18×211 mean?
W means a wide flange shape. 18 is its nominal depth in inches (the actual depth is 20.7 in) and 211 is its weight in pounds per foot.
How much does a W18×211 weigh?
211 pounds per foot, so a 20 ft W18×211 weighs about 4,220 pounds.
How far can a W18×211 span?
It depends on the load. Braced along its length, it carries 131.7 kips per foot of factored load at 10 ft and 5.44 kips per foot at 52 ft; the load table has the spans in between. Floor beams are often 31 to 41 ft for this depth (span-to-depth ratios of about 18 to 24), where deflection usually governs.
Is a W18×211 a compact section?
Yes. Its flanges (bf/2tf = 3.02) and web (h/tw = 15.1) are both compact for bending in 50 ksi steel.