W14×311 Steel Beam
A W14×311 is a wide flange steel beam 17.1 inches deep with 16.2-inch flanges, weighing 311 pounds per foot. In ASTM A992 steel (Fy = 50 ksi) it has a design bending strength of 2,261 kip-ft (LRFD) when its compression flange is braced, and a design shear strength of 723 kips.
Design a W14×311 beam Opens a 27 ft span in the free beam designer.
W14×311 dimensions
| Dimension | Value |
|---|---|
| Depth, d | 17.1 in |
| Flange width, bf | 16.2 in |
| Flange thickness, tf | 2.26 in |
| Web thickness, tw | 1.41 in |
| Distance to web toe of fillet, kdes | 2.86 in |
| Distance between flange centroids, ho | 14.84 in |
| Cross-sectional area, A | 91.4 in2 |
| Weight | 311 lb/ft |
Dimensions are AISC design values. Detailing dimensions are rounded to the nearest 1/16 in.
W14×311 section properties
| Property | Strong axis (x) | Weak axis (y) |
|---|---|---|
| Moment of inertia, I | 4330 in4 | 1610 in4 |
| Elastic section modulus, S | 506 in3 | 199 in3 |
| Plastic section modulus, Z | 603 in3 | 304 in3 |
| Radius of gyration, r | 6.88 in | 4.20 in |
| Torsion and slenderness | Value |
|---|---|
| Torsional constant, J | 136 in4 |
| Warping constant, Cw | 89100 in6 |
| Effective radius of gyration, rts | 4.87 in |
| Flange slenderness, bf/2tf | 3.59 |
| Web slenderness, h/tw | 8.09 |
W14×311 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 = 2,261 kip-ft | Mn/Ω = 1,504 kip-ft |
| Shear | φVn = 723 kips | Vn/Ω = 482 kips |
If the compression flange isn't braced, the beam can buckle sideways before it yields. Up to Lp = 14.8 ft between braces it keeps its full strength; past Lr = 125.1 ft it buckles elastically. With uniform moment between braces (Cb = 1.0):
| Unbraced length, Lb | φMn (LRFD) | Mn/Ω (ASD) |
|---|---|---|
| Braced | 2,261 kip-ft | 1,504 kip-ft |
| 10 ft | 2,261 kip-ft | 1,504 kip-ft |
| 14.8 ft (Lp) | 2,261 kip-ft | 1,504 kip-ft |
| 20 ft | 2,218 kip-ft | 1,475 kip-ft |
| 30 ft | 2,133 kip-ft | 1,419 kip-ft |
| 40 ft | 2,048 kip-ft | 1,363 kip-ft |
| 50 ft | 1,964 kip-ft | 1,307 kip-ft |
| 60 ft | 1,879 kip-ft | 1,250 kip-ft |
| 70 ft | 1,795 kip-ft | 1,194 kip-ft |
| 80 ft | 1,710 kip-ft | 1,138 kip-ft |
| 90 ft | 1,625 kip-ft | 1,081 kip-ft |
| 100 ft | 1,541 kip-ft | 1,025 kip-ft |
| 110 ft | 1,456 kip-ft | 969 kip-ft |
| 125.1 ft (Lr) | 1,328 kip-ft | 883 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.
W14×311 load table by span
The largest uniform load a simply supported W14×311 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 0.311 kips per foot.
| Span | Factored load (LRFD) | Allowable load (ASD) | Load at span/360 | Load at span/240 |
|---|---|---|---|---|
| 9 ft | 160.7* | 107.2* | 255.2 | 382.8 |
| 11 ft | 131.5* | 87.7* | 139.8 | 209.7 |
| 13 ft | 107.0 | 71.2 | 84.7 | 127.0 |
| 15 ft | 80.4 | 53.5 | 55.1 | 82.7 |
| 17 ft | 62.6 | 41.6 | 37.9 | 56.8 |
| 19 ft | 50.1 | 33.3 | 27.1 | 40.7 |
| 21 ft | 41.0 | 27.3 | 20.1 | 30.1 |
| 23 ft | 34.2 | 22.8 | 15.3 | 22.9 |
| 25 ft | 28.9 | 19.3 | 11.9 | 17.9 |
| 27 ft | 24.8 | 16.5 | 9.45 | 14.2 |
| 29 ft | 21.5 | 14.3 | 7.63 | 11.4 |
| 31 ft | 18.8 | 12.5 | 6.24 | 9.37 |
| 33 ft | 16.6 | 11.1 | 5.18 | 7.76 |
| 35 ft | 14.8 | 9.83 | 4.34 | 6.51 |
| 37 ft | 13.2 | 8.79 | 3.67 | 5.51 |
| 39 ft | 11.9 | 7.91 | 3.14 | 4.70 |
| 41 ft | 10.8 | 7.16 | 2.70 | 4.05 |
| 43 ft | 9.78 | 6.51 | 2.34 | 3.51 |
- 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 27 ft span, a W14×311 carries a factored load of 24.8 kips per foot (LRFD) or an allowable load of 16.5 kips per foot (ASD). A live load of 9.45 kips per foot would deflect it span/360, which is 0.90 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.
W14×311 questions
What does W14×311 mean?
W means a wide flange shape. 14 is its nominal depth in inches (the actual depth is 17.1 in) and 311 is its weight in pounds per foot.
How much does a W14×311 weigh?
311 pounds per foot, so a 20 ft W14×311 weighs about 6,220 pounds.
How far can a W14×311 span?
It depends on the load. Braced along its length, it carries 160.7 kips per foot of factored load at 9 ft and 9.78 kips per foot at 43 ft; the load table has the spans in between. Floor beams are often 26 to 34 ft for this depth (span-to-depth ratios of about 18 to 24), where deflection usually governs.
Is a W14×311 a compact section?
Yes. Its flanges (bf/2tf = 3.59) and web (h/tw = 8.09) are both compact for bending in 50 ksi steel.