W14×550 Steel Beam
A W14×550 is a wide flange steel beam 20.2 inches deep with 17.2-inch flanges, weighing 550 pounds per foot. In ASTM A992 steel (Fy = 50 ksi) it has a design bending strength of 4,425 kip-ft (LRFD) when its compression flange is braced, and a design shear strength of 1,442 kips.
Design a W14×550 beam Opens a 30 ft span in the free beam designer.
W14×550 dimensions
| Dimension | Value |
|---|---|
| Depth, d | 20.2 in |
| Flange width, bf | 17.2 in |
| Flange thickness, tf | 3.82 in |
| Web thickness, tw | 2.38 in |
| Distance to web toe of fillet, kdes | 4.42 in |
| Distance between flange centroids, ho | 16.38 in |
| Cross-sectional area, A | 162 in2 |
| Weight | 550 lb/ft |
Dimensions are AISC design values. Detailing dimensions are rounded to the nearest 1/16 in.
W14×550 section properties
| Property | Strong axis (x) | Weak axis (y) |
|---|---|---|
| Moment of inertia, I | 9430 in4 | 3250 in4 |
| Elastic section modulus, S | 931 in3 | 378 in3 |
| Plastic section modulus, Z | 1180 in3 | 583 in3 |
| Radius of gyration, r | 7.63 in | 4.49 in |
| Torsion and slenderness | Value |
|---|---|
| Torsional constant, J | 669 in4 |
| Warping constant, Cw | 219000 in6 |
| Effective radius of gyration, rts | 5.35 in |
| Flange slenderness, bf/2tf | 2.25 |
| Web slenderness, h/tw | 4.79 |
W14×550 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 = 4,425 kip-ft | Mn/Ω = 2,944 kip-ft |
| Shear | φVn = 1,442 kips | Vn/Ω = 962 kips |
If the compression flange isn't braced, the beam can buckle sideways before it yields. Up to Lp = 15.9 ft between braces it keeps its full strength; past Lr = 213.6 ft it buckles elastically. With uniform moment between braces (Cb = 1.0):
| Unbraced length, Lb | φMn (LRFD) | Mn/Ω (ASD) |
|---|---|---|
| Braced | 4,425 kip-ft | 2,944 kip-ft |
| 10 ft | 4,425 kip-ft | 2,944 kip-ft |
| 15.9 ft (Lp) | 4,425 kip-ft | 2,944 kip-ft |
| 20 ft | 4,384 kip-ft | 2,917 kip-ft |
| 30 ft | 4,283 kip-ft | 2,850 kip-ft |
| 40 ft | 4,183 kip-ft | 2,783 kip-ft |
| 50 ft | 4,083 kip-ft | 2,717 kip-ft |
| 60 ft | 3,983 kip-ft | 2,650 kip-ft |
| 70 ft | 3,883 kip-ft | 2,583 kip-ft |
| 80 ft | 3,782 kip-ft | 2,517 kip-ft |
| 90 ft | 3,682 kip-ft | 2,450 kip-ft |
| 100 ft | 3,582 kip-ft | 2,383 kip-ft |
| 110 ft | 3,482 kip-ft | 2,317 kip-ft |
| 213.6 ft (Lr) | 2,444 kip-ft | 1,626 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.
W14×550 load table by span
The largest uniform load a simply supported W14×550 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 0.550 kips per foot.
| Span | Factored load (LRFD) | Allowable load (ASD) | Load at span/360 | Load at span/240 |
|---|---|---|---|---|
| 10 ft | 288.5* | 192.3* | 405.1 | 607.7 |
| 12 ft | 240.4* | 160.3* | 234.5 | 351.7 |
| 14 ft | 180.6 | 120.2 | 147.6 | 221.5 |
| 16 ft | 138.3 | 92.0 | 98.9 | 148.4 |
| 18 ft | 109.3 | 72.7 | 69.5 | 104.2 |
| 20 ft | 88.5 | 58.9 | 50.6 | 76.0 |
| 22 ft | 73.1 | 48.7 | 38.0 | 57.1 |
| 24 ft | 61.5 | 40.9 | 29.3 | 44.0 |
| 26 ft | 52.4 | 34.8 | 23.1 | 34.6 |
| 28 ft | 45.2 | 30.0 | 18.5 | 27.7 |
| 30 ft | 39.3 | 26.2 | 15.0 | 22.5 |
| 32 ft | 34.6 | 23.0 | 12.4 | 18.5 |
| 34 ft | 30.6 | 20.4 | 10.3 | 15.5 |
| 36 ft | 27.3 | 18.2 | 8.68 | 13.0 |
| 38 ft | 24.5 | 16.3 | 7.38 | 11.1 |
| 40 ft | 22.1 | 14.7 | 6.33 | 9.50 |
| 42 ft | 20.1 | 13.4 | 5.47 | 8.20 |
| 44 ft | 18.3 | 12.2 | 4.76 | 7.13 |
| 46 ft | 16.7 | 11.1 | 4.16 | 6.24 |
| 48 ft | 15.4 | 10.2 | 3.66 | 5.50 |
| 50 ft | 14.2 | 9.42 | 3.24 | 4.86 |
- 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 30 ft span, a W14×550 carries a factored load of 39.3 kips per foot (LRFD) or an allowable load of 26.2 kips per foot (ASD). A live load of 15.0 kips per foot would deflect it span/360, which is 1.00 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.
W14×550 questions
What does W14×550 mean?
W means a wide flange shape. 14 is its nominal depth in inches (the actual depth is 20.2 in) and 550 is its weight in pounds per foot.
How much does a W14×550 weigh?
550 pounds per foot, so a 20 ft W14×550 weighs about 11,000 pounds.
How far can a W14×550 span?
It depends on the load. Braced along its length, it carries 288.5 kips per foot of factored load at 10 ft and 14.2 kips per foot at 50 ft; the load table has the spans in between. Floor beams are often 30 to 40 ft for this depth (span-to-depth ratios of about 18 to 24), where deflection usually governs.
Is a W14×550 a compact section?
Yes. Its flanges (bf/2tf = 2.25) and web (h/tw = 4.79) are both compact for bending in 50 ksi steel.