W27×368 Steel Beam
A W27×368 is a wide flange steel beam 30.4 inches deep with 14.7-inch flanges, weighing 368 pounds per foot. In ASTM A992 steel (Fy = 50 ksi) it has a design bending strength of 4,650 kip-ft (LRFD) when its compression flange is braced, and a design shear strength of 1,259 kips.
Design a W27×368 beam Opens a 45 ft span in the free beam designer.
W27×368 dimensions
| Dimension | Value |
|---|---|
| Depth, d | 30.4 in |
| Flange width, bf | 14.7 in |
| Flange thickness, tf | 2.48 in |
| Web thickness, tw | 1.38 in |
| Distance to web toe of fillet, kdes | 3.27 in |
| Distance between flange centroids, ho | 27.92 in |
| Cross-sectional area, A | 108 in2 |
| Weight | 368 lb/ft |
Dimensions are AISC design values. Detailing dimensions are rounded to the nearest 1/16 in.
W27×368 section properties
| Property | Strong axis (x) | Weak axis (y) |
|---|---|---|
| Moment of inertia, I | 16200 in4 | 1310 in4 |
| Elastic section modulus, S | 1060 in3 | 179 in3 |
| Plastic section modulus, Z | 1240 in3 | 279 in3 |
| Radius of gyration, r | 12.2 in | 3.48 in |
| Torsion and slenderness | Value |
|---|---|
| Torsional constant, J | 170 in4 |
| Warping constant, Cw | 255000 in6 |
| Effective radius of gyration, rts | 4.15 in |
| Flange slenderness, bf/2tf | 2.96 |
| Web slenderness, h/tw | 17.3 |
W27×368 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 = 4,650 kip-ft | Mn/Ω = 3,094 kip-ft |
| Shear | φVn = 1,259 kips | Vn/Ω = 839 kips |
If the compression flange isn't braced, the beam can buckle sideways before it yields. Up to Lp = 12.3 ft between braces it keeps its full strength; past Lr = 62.0 ft it buckles elastically. With uniform moment between braces (Cb = 1.0):
| Unbraced length, Lb | φMn (LRFD) | Mn/Ω (ASD) |
|---|---|---|
| Braced | 4,650 kip-ft | 3,094 kip-ft |
| 10 ft | 4,650 kip-ft | 3,094 kip-ft |
| 12.3 ft (Lp) | 4,650 kip-ft | 3,094 kip-ft |
| 20 ft | 4,360 kip-ft | 2,901 kip-ft |
| 30 ft | 3,984 kip-ft | 2,651 kip-ft |
| 40 ft | 3,609 kip-ft | 2,401 kip-ft |
| 50 ft | 3,233 kip-ft | 2,151 kip-ft |
| 60 ft | 2,857 kip-ft | 1,901 kip-ft |
| 62.0 ft (Lr) | 2,781 kip-ft | 1,850 kip-ft |
| 70 ft | 2,445 kip-ft | 1,627 kip-ft |
| 80 ft | 2,126 kip-ft | 1,415 kip-ft |
| 90 ft | 1,882 kip-ft | 1,252 kip-ft |
| 100 ft | 1,689 kip-ft | 1,124 kip-ft |
| 110 ft | 1,532 kip-ft | 1,019 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.
W27×368 load table by span
The largest uniform load a simply supported W27×368 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 0.368 kips per foot.
| Span | Factored load (LRFD) | Allowable load (ASD) | Load at span/360 | Load at span/240 |
|---|---|---|---|---|
| 15 ft | 165.3 | 110.0 | 206.2 | 309.3 |
| 17 ft | 128.7 | 85.6 | 141.7 | 212.5 |
| 19 ft | 103.0 | 68.6 | 101.5 | 152.2 |
| 21 ft | 84.4 | 56.1 | 75.2 | 112.7 |
| 23 ft | 70.3 | 46.8 | 57.2 | 85.8 |
| 25 ft | 59.5 | 39.6 | 44.5 | 66.8 |
| 27 ft | 51.0 | 34.0 | 35.4 | 53.0 |
| 29 ft | 44.2 | 29.4 | 28.5 | 42.8 |
| 31 ft | 38.7 | 25.8 | 23.4 | 35.0 |
| 33 ft | 34.2 | 22.7 | 19.4 | 29.1 |
| 35 ft | 30.4 | 20.2 | 16.2 | 24.3 |
| 37 ft | 27.2 | 18.1 | 13.7 | 20.6 |
| 39 ft | 24.5 | 16.3 | 11.7 | 17.6 |
| 41 ft | 22.1 | 14.7 | 10.1 | 15.1 |
| 43 ft | 20.1 | 13.4 | 8.75 | 13.1 |
| 45 ft | 18.4 | 12.2 | 7.64 | 11.5 |
| 47 ft | 16.8 | 11.2 | 6.70 | 10.1 |
| 49 ft | 15.5 | 10.3 | 5.92 | 8.87 |
| 51 ft | 14.3 | 9.52 | 5.25 | 7.87 |
| 53 ft | 13.2 | 8.81 | 4.68 | 7.01 |
| 55 ft | 12.3 | 8.18 | 4.18 | 6.27 |
| 57 ft | 11.4 | 7.62 | 3.76 | 5.64 |
| 59 ft | 10.7 | 7.11 | 3.39 | 5.08 |
| 61 ft | 10.00 | 6.65 | 3.07 | 4.60 |
| 63 ft | 9.37 | 6.24 | 2.78 | 4.18 |
| 65 ft | 8.80 | 5.86 | 2.53 | 3.80 |
| 67 ft | 8.29 | 5.51 | 2.31 | 3.47 |
| 69 ft | 7.81 | 5.20 | 2.12 | 3.18 |
| 71 ft | 7.38 | 4.91 | 1.94 | 2.92 |
| 73 ft | 6.98 | 4.64 | 1.79 | 2.68 |
| 75 ft | 6.61 | 4.40 | 1.65 | 2.47 |
- 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 45 ft span, a W27×368 carries a factored load of 18.4 kips per foot (LRFD) or an allowable load of 12.2 kips per foot (ASD). A live load of 7.64 kips per foot would deflect it span/360, which is 1.50 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.
W27×368 questions
What does W27×368 mean?
W means a wide flange shape. 27 is its nominal depth in inches (the actual depth is 30.4 in) and 368 is its weight in pounds per foot.
How much does a W27×368 weigh?
368 pounds per foot, so a 20 ft W27×368 weighs about 7,360 pounds.
How far can a W27×368 span?
It depends on the load. Braced along its length, it carries 165.3 kips per foot of factored load at 15 ft and 6.61 kips per foot at 75 ft; the load table has the spans in between. Floor beams are often 46 to 61 ft for this depth (span-to-depth ratios of about 18 to 24), where deflection usually governs.
Is a W27×368 a compact section?
Yes. Its flanges (bf/2tf = 2.96) and web (h/tw = 17.3) are both compact for bending in 50 ksi steel.