W40×277 Steel Beam
A W40×277 is a wide flange steel beam 39.7 inches deep with 15.8-inch flanges, weighing 277 pounds per foot. In ASTM A992 steel (Fy = 50 ksi) it has a design bending strength of 4,688 kip-ft (LRFD) when its compression flange is braced, and a design shear strength of 989 kips.
Design a W40×277 beam Opens a 60 ft span in the free beam designer.
W40×277 dimensions
| Dimension | Value |
|---|---|
| Depth, d | 39.7 in |
| Flange width, bf | 15.8 in |
| Flange thickness, tf | 1.58 in |
| Web thickness, tw | 0.830 in |
| Distance to web toe of fillet, kdes | 2.76 in |
| Distance between flange centroids, ho | 38.12 in |
| Cross-sectional area, A | 81.4 in2 |
| Weight | 277 lb/ft |
Dimensions are AISC design values. Detailing dimensions are rounded to the nearest 1/16 in.
W40×277 section properties
| Property | Strong axis (x) | Weak axis (y) |
|---|---|---|
| Moment of inertia, I | 21900 in4 | 1040 in4 |
| Elastic section modulus, S | 1100 in3 | 132 in3 |
| Plastic section modulus, Z | 1250 in3 | 204 in3 |
| Radius of gyration, r | 16.4 in | 3.58 in |
| Torsion and slenderness | Value |
|---|---|
| Torsional constant, J | 51.5 in4 |
| Warping constant, Cw | 379000 in6 |
| Effective radius of gyration, rts | 4.25 in |
| Flange slenderness, bf/2tf | 5.03 |
| Web slenderness, h/tw | 41.2 |
W40×277 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 = 4,688 kip-ft | Mn/Ω = 3,119 kip-ft |
| Shear | φVn = 989 kips | Vn/Ω = 659 kips |
If the compression flange isn't braced, the beam can buckle sideways before it yields. Up to Lp = 12.6 ft between braces it keeps its full strength; past Lr = 38.8 ft it buckles elastically. With uniform moment between braces (Cb = 1.0):
| Unbraced length, Lb | φMn (LRFD) | Mn/Ω (ASD) |
|---|---|---|
| Braced | 4,688 kip-ft | 3,119 kip-ft |
| 10 ft | 4,688 kip-ft | 3,119 kip-ft |
| 12.7 ft (Lp) | 4,687 kip-ft | 3,119 kip-ft |
| 20 ft | 4,181 kip-ft | 2,782 kip-ft |
| 30 ft | 3,493 kip-ft | 2,324 kip-ft |
| 38.8 ft (Lr) | 2,884 kip-ft | 1,919 kip-ft |
| 40 ft | 2,758 kip-ft | 1,835 kip-ft |
| 50 ft | 2,020 kip-ft | 1,344 kip-ft |
| 60 ft | 1,592 kip-ft | 1,059 kip-ft |
| 70 ft | 1,316 kip-ft | 875 kip-ft |
| 80 ft | 1,122 kip-ft | 747 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.
W40×277 load table by span
The largest uniform load a simply supported W40×277 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 0.277 kips per foot.
| Span | Factored load (LRFD) | Allowable load (ASD) | Load at span/360 | Load at span/240 |
|---|---|---|---|---|
| 20 ft | 93.8 | 62.4 | 117.6 | 176.4 |
| 22 ft | 77.5 | 51.5 | 88.4 | 132.5 |
| 24 ft | 65.1 | 43.3 | 68.1 | 102.1 |
| 26 ft | 55.5 | 36.9 | 53.5 | 80.3 |
| 28 ft | 47.8 | 31.8 | 42.9 | 64.3 |
| 30 ft | 41.7 | 27.7 | 34.8 | 52.3 |
| 32 ft | 36.6 | 24.4 | 28.7 | 43.1 |
| 34 ft | 32.4 | 21.6 | 23.9 | 35.9 |
| 36 ft | 28.9 | 19.3 | 20.2 | 30.2 |
| 38 ft | 26.0 | 17.3 | 17.1 | 25.7 |
| 40 ft | 23.4 | 15.6 | 14.7 | 22.1 |
| 42 ft | 21.3 | 14.1 | 12.7 | 19.0 |
| 44 ft | 19.4 | 12.9 | 11.0 | 16.6 |
| 46 ft | 17.7 | 11.8 | 9.67 | 14.5 |
| 48 ft | 16.3 | 10.8 | 8.51 | 12.8 |
| 50 ft | 15.0 | 9.98 | 7.53 | 11.3 |
| 52 ft | 13.9 | 9.23 | 6.69 | 10.0 |
| 54 ft | 12.9 | 8.56 | 5.98 | 8.96 |
| 56 ft | 12.0 | 7.96 | 5.36 | 8.04 |
| 58 ft | 11.1 | 7.42 | 4.82 | 7.23 |
| 60 ft | 10.4 | 6.93 | 4.36 | 6.53 |
| 62 ft | 9.76 | 6.49 | 3.95 | 5.92 |
| 64 ft | 9.16 | 6.09 | 3.59 | 5.38 |
| 66 ft | 8.61 | 5.73 | 3.27 | 4.91 |
| 68 ft | 8.11 | 5.40 | 2.99 | 4.49 |
| 70 ft | 7.65 | 5.09 | 2.74 | 4.11 |
| 72 ft | 7.23 | 4.81 | 2.52 | 3.78 |
| 74 ft | 6.85 | 4.56 | 2.32 | 3.48 |
| 76 ft | 6.49 | 4.32 | 2.14 | 3.22 |
| 78 ft | 6.16 | 4.10 | 1.98 | 2.97 |
| 80 ft | 5.86 | 3.90 | 1.84 | 2.76 |
| 82 ft | 5.58 | 3.71 | 1.71 | 2.56 |
| 84 ft | 5.31 | 3.54 | 1.59 | 2.38 |
| 86 ft | 5.07 | 3.37 | 1.48 | 2.22 |
| 88 ft | 4.84 | 3.22 | 1.38 | 2.07 |
| 90 ft | 4.63 | 3.08 | 1.29 | 1.94 |
| 92 ft | 4.43 | 2.95 | 1.21 | 1.81 |
| 94 ft | 4.24 | 2.82 | 1.13 | 1.70 |
| 96 ft | 4.07 | 2.71 | 1.06 | 1.60 |
| 98 ft | 3.90 | 2.60 | 1.00 | 1.50 |
- 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 60 ft span, a W40×277 carries a factored load of 10.4 kips per foot (LRFD) or an allowable load of 6.93 kips per foot (ASD). A live load of 4.36 kips per foot would deflect it span/360, which is 2.00 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.
W40×277 questions
What does W40×277 mean?
W means a wide flange shape. 40 is its nominal depth in inches (the actual depth is 39.7 in) and 277 is its weight in pounds per foot.
How much does a W40×277 weigh?
277 pounds per foot, so a 20 ft W40×277 weighs about 5,540 pounds.
How far can a W40×277 span?
It depends on the load. Braced along its length, it carries 93.8 kips per foot of factored load at 20 ft and 3.90 kips per foot at 98 ft; the load table has the spans in between. Floor beams are often 60 to 79 ft for this depth (span-to-depth ratios of about 18 to 24), where deflection usually governs.
Is a W40×277 a compact section?
Yes. Its flanges (bf/2tf = 5.03) and web (h/tw = 41.2) are both compact for bending in 50 ksi steel.