W40×183 Steel Beam
A W40×183 is a wide flange steel beam 39 inches deep with 11.8-inch flanges, weighing 183 pounds per foot. In ASTM A992 steel (Fy = 50 ksi) it has a design bending strength of 2,903 kip-ft (LRFD) when its compression flange is braced, and a design shear strength of 761 kips.
Design a W40×183 beam Opens a 60 ft span in the free beam designer.
W40×183 dimensions
| Dimension | Value |
|---|---|
| Depth, d | 39.0 in |
| Flange width, bf | 11.8 in |
| Flange thickness, tf | 1.20 in |
| Web thickness, tw | 0.650 in |
| Distance to web toe of fillet, kdes | 2.38 in |
| Distance between flange centroids, ho | 37.80 in |
| Cross-sectional area, A | 53.3 in2 |
| Weight | 183 lb/ft |
Dimensions are AISC design values. Detailing dimensions are rounded to the nearest 1/16 in.
W40×183 section properties
| Property | Strong axis (x) | Weak axis (y) |
|---|---|---|
| Moment of inertia, I | 13200 in4 | 331 in4 |
| Elastic section modulus, S | 675 in3 | 56.0 in3 |
| Plastic section modulus, Z | 774 in3 | 88.3 in3 |
| Radius of gyration, r | 15.7 in | 2.49 in |
| Torsion and slenderness | Value |
|---|---|
| Torsional constant, J | 19.3 in4 |
| Warping constant, Cw | 118000 in6 |
| Effective radius of gyration, rts | 3.04 in |
| Flange slenderness, bf/2tf | 4.92 |
| Web slenderness, h/tw | 52.6 |
W40×183 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 = 2,903 kip-ft | Mn/Ω = 1,931 kip-ft |
| Shear | φVn = 761 kips | Vn/Ω = 507 kips |
If the compression flange isn't braced, the beam can buckle sideways before it yields. Up to Lp = 8.8 ft between braces it keeps its full strength; past Lr = 25.9 ft it buckles elastically. With uniform moment between braces (Cb = 1.0):
| Unbraced length, Lb | φMn (LRFD) | Mn/Ω (ASD) |
|---|---|---|
| Braced | 2,903 kip-ft | 1,931 kip-ft |
| 5 ft | 2,903 kip-ft | 1,931 kip-ft |
| 8.8 ft (Lp) | 2,902 kip-ft | 1,931 kip-ft |
| 10 ft | 2,823 kip-ft | 1,878 kip-ft |
| 15 ft | 2,491 kip-ft | 1,658 kip-ft |
| 20 ft | 2,160 kip-ft | 1,437 kip-ft |
| 25 ft | 1,829 kip-ft | 1,217 kip-ft |
| 25.9 ft (Lr) | 1,772 kip-ft | 1,179 kip-ft |
| 30 ft | 1,399 kip-ft | 931 kip-ft |
| 35 ft | 1,108 kip-ft | 737 kip-ft |
| 40 ft | 915 kip-ft | 609 kip-ft |
| 45 ft | 778 kip-ft | 518 kip-ft |
| 50 ft | 676 kip-ft | 450 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.
W40×183 load table by span
The largest uniform load a simply supported W40×183 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 0.183 kips per foot.
| Span | Factored load (LRFD) | Allowable load (ASD) | Load at span/360 | Load at span/240 |
|---|---|---|---|---|
| 20 ft | 58.1 | 38.6 | 70.9 | 106.3 |
| 22 ft | 48.0 | 31.9 | 53.3 | 79.9 |
| 24 ft | 40.3 | 26.8 | 41.0 | 61.5 |
| 26 ft | 34.3 | 22.9 | 32.3 | 48.4 |
| 28 ft | 29.6 | 19.7 | 25.8 | 38.8 |
| 30 ft | 25.8 | 17.2 | 21.0 | 31.5 |
| 32 ft | 22.7 | 15.1 | 17.3 | 26.0 |
| 34 ft | 20.1 | 13.4 | 14.4 | 21.6 |
| 36 ft | 17.9 | 11.9 | 12.2 | 18.2 |
| 38 ft | 16.1 | 10.7 | 10.3 | 15.5 |
| 40 ft | 14.5 | 9.66 | 8.86 | 13.3 |
| 42 ft | 13.2 | 8.76 | 7.65 | 11.5 |
| 44 ft | 12.0 | 7.98 | 6.66 | 9.99 |
| 46 ft | 11.0 | 7.30 | 5.83 | 8.74 |
| 48 ft | 10.1 | 6.71 | 5.13 | 7.69 |
| 50 ft | 9.29 | 6.18 | 4.54 | 6.81 |
| 52 ft | 8.59 | 5.71 | 4.03 | 6.05 |
| 54 ft | 7.96 | 5.30 | 3.60 | 5.40 |
| 56 ft | 7.40 | 4.93 | 3.23 | 4.84 |
| 58 ft | 6.90 | 4.59 | 2.91 | 4.36 |
| 60 ft | 6.45 | 4.29 | 2.63 | 3.94 |
| 62 ft | 6.04 | 4.02 | 2.38 | 3.57 |
| 64 ft | 5.67 | 3.77 | 2.16 | 3.25 |
| 66 ft | 5.33 | 3.55 | 1.97 | 2.96 |
| 68 ft | 5.02 | 3.34 | 1.80 | 2.71 |
| 70 ft | 4.74 | 3.15 | 1.65 | 2.48 |
| 72 ft | 4.48 | 2.98 | 1.52 | 2.28 |
| 74 ft | 4.24 | 2.82 | 1.40 | 2.10 |
| 76 ft | 4.02 | 2.67 | 1.29 | 1.94 |
| 78 ft | 3.82 | 2.54 | 1.20 | 1.79 |
| 80 ft | 3.63 | 2.41 | 1.11 | 1.66 |
| 82 ft | 3.45 | 2.30 | 1.03 | 1.54 |
| 84 ft | 3.29 | 2.19 | 0.96 | 1.44 |
| 86 ft | 3.14 | 2.09 | 0.89 | 1.34 |
| 88 ft | 3.00 | 1.99 | 0.83 | 1.25 |
| 90 ft | 2.87 | 1.91 | 0.78 | 1.17 |
| 92 ft | 2.74 | 1.83 | 0.73 | 1.09 |
| 94 ft | 2.63 | 1.75 | 0.68 | 1.02 |
| 96 ft | 2.52 | 1.68 | 0.64 | 0.96 |
| 98 ft | 2.42 | 1.61 | 0.60 | 0.90 |
- 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 W40×183 carries a factored load of 6.45 kips per foot (LRFD) or an allowable load of 4.29 kips per foot (ASD). A live load of 2.63 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.
W40×183 questions
What does W40×183 mean?
W means a wide flange shape. 40 is its nominal depth in inches (the actual depth is 39.0 in) and 183 is its weight in pounds per foot.
How much does a W40×183 weigh?
183 pounds per foot, so a 20 ft W40×183 weighs about 3,660 pounds.
How far can a W40×183 span?
It depends on the load. Braced along its length, it carries 58.1 kips per foot of factored load at 20 ft and 2.42 kips per foot at 98 ft; the load table has the spans in between. Floor beams are often 59 to 78 ft for this depth (span-to-depth ratios of about 18 to 24), where deflection usually governs.
Is a W40×183 a compact section?
Yes. Its flanges (bf/2tf = 4.92) and web (h/tw = 52.6) are both compact for bending in 50 ksi steel.