W24×370 Steel Beam
A W24×370 is a wide flange steel beam 28 inches deep with 13.7-inch flanges, weighing 370 pounds per foot. In ASTM A992 steel (Fy = 50 ksi) it has a design bending strength of 4,238 kip-ft (LRFD) when its compression flange is braced, and a design shear strength of 1,277 kips.
Design a W24×370 beam Opens a 42 ft span in the free beam designer.
W24×370 dimensions
| Dimension | Value |
|---|---|
| Depth, d | 28.0 in |
| Flange width, bf | 13.7 in |
| Flange thickness, tf | 2.72 in |
| Web thickness, tw | 1.52 in |
| Distance to web toe of fillet, kdes | 3.22 in |
| Distance between flange centroids, ho | 25.28 in |
| Cross-sectional area, A | 109 in2 |
| Weight | 370 lb/ft |
Dimensions are AISC design values. Detailing dimensions are rounded to the nearest 1/16 in.
W24×370 section properties
| Property | Strong axis (x) | Weak axis (y) |
|---|---|---|
| Moment of inertia, I | 13400 in4 | 1160 in4 |
| Elastic section modulus, S | 957 in3 | 170 in3 |
| Plastic section modulus, Z | 1130 in3 | 267 in3 |
| Radius of gyration, r | 11.1 in | 3.27 in |
| Torsion and slenderness | Value |
|---|---|
| Torsional constant, J | 201 in4 |
| Warping constant, Cw | 186000 in6 |
| Effective radius of gyration, rts | 3.92 in |
| Flange slenderness, bf/2tf | 2.51 |
| Web slenderness, h/tw | 14.2 |
W24×370 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 = 4,238 kip-ft | Mn/Ω = 2,819 kip-ft |
| Shear | φVn = 1,277 kips | Vn/Ω = 851 kips |
If the compression flange isn't braced, the beam can buckle sideways before it yields. Up to Lp = 11.6 ft between braces it keeps its full strength; past Lr = 69.2 ft it buckles elastically. With uniform moment between braces (Cb = 1.0):
| Unbraced length, Lb | φMn (LRFD) | Mn/Ω (ASD) |
|---|---|---|
| Braced | 4,238 kip-ft | 2,819 kip-ft |
| 10 ft | 4,238 kip-ft | 2,819 kip-ft |
| 11.6 ft (Lp) | 4,238 kip-ft | 2,819 kip-ft |
| 20 ft | 3,984 kip-ft | 2,651 kip-ft |
| 30 ft | 3,685 kip-ft | 2,452 kip-ft |
| 40 ft | 3,385 kip-ft | 2,252 kip-ft |
| 50 ft | 3,086 kip-ft | 2,053 kip-ft |
| 60 ft | 2,786 kip-ft | 1,854 kip-ft |
| 69.2 ft (Lr) | 2,511 kip-ft | 1,671 kip-ft |
| 70 ft | 2,480 kip-ft | 1,650 kip-ft |
| 80 ft | 2,161 kip-ft | 1,438 kip-ft |
| 90 ft | 1,916 kip-ft | 1,275 kip-ft |
| 100 ft | 1,721 kip-ft | 1,145 kip-ft |
| 110 ft | 1,563 kip-ft | 1,040 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.
W24×370 load table by span
The largest uniform load a simply supported W24×370 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 0.370 kips per foot.
| Span | Factored load (LRFD) | Allowable load (ASD) | Load at span/360 | Load at span/240 |
|---|---|---|---|---|
| 14 ft | 173.0 | 115.1 | 209.8 | 314.7 |
| 16 ft | 132.4 | 88.1 | 140.6 | 210.8 |
| 18 ft | 104.6 | 69.6 | 98.7 | 148.1 |
| 20 ft | 84.8 | 56.4 | 72.0 | 107.9 |
| 22 ft | 70.0 | 46.6 | 54.1 | 81.1 |
| 24 ft | 58.9 | 39.2 | 41.6 | 62.5 |
| 26 ft | 50.1 | 33.4 | 32.8 | 49.1 |
| 28 ft | 43.2 | 28.8 | 26.2 | 39.3 |
| 30 ft | 37.7 | 25.1 | 21.3 | 32.0 |
| 32 ft | 33.1 | 22.0 | 17.6 | 26.4 |
| 34 ft | 29.3 | 19.5 | 14.6 | 22.0 |
| 36 ft | 26.2 | 17.4 | 12.3 | 18.5 |
| 38 ft | 23.5 | 15.6 | 10.5 | 15.7 |
| 40 ft | 21.2 | 14.1 | 9.00 | 13.5 |
| 42 ft | 19.2 | 12.8 | 7.77 | 11.7 |
| 44 ft | 17.5 | 11.7 | 6.76 | 10.1 |
| 46 ft | 16.0 | 10.7 | 5.91 | 8.87 |
| 48 ft | 14.7 | 9.79 | 5.21 | 7.81 |
| 50 ft | 13.6 | 9.02 | 4.61 | 6.91 |
| 52 ft | 12.5 | 8.34 | 4.09 | 6.14 |
| 54 ft | 11.6 | 7.73 | 3.66 | 5.48 |
| 56 ft | 10.8 | 7.19 | 3.28 | 4.92 |
| 58 ft | 10.1 | 6.70 | 2.95 | 4.43 |
| 60 ft | 9.42 | 6.27 | 2.67 | 4.00 |
| 62 ft | 8.82 | 5.87 | 2.42 | 3.62 |
| 64 ft | 8.28 | 5.51 | 2.20 | 3.29 |
| 66 ft | 7.78 | 5.18 | 2.00 | 3.00 |
| 68 ft | 7.33 | 4.88 | 1.83 | 2.75 |
| 70 ft | 6.92 | 4.60 | 1.68 | 2.52 |
- 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 42 ft span, a W24×370 carries a factored load of 19.2 kips per foot (LRFD) or an allowable load of 12.8 kips per foot (ASD). A live load of 7.77 kips per foot would deflect it span/360, which is 1.40 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.
W24×370 questions
What does W24×370 mean?
W means a wide flange shape. 24 is its nominal depth in inches (the actual depth is 28.0 in) and 370 is its weight in pounds per foot.
How much does a W24×370 weigh?
370 pounds per foot, so a 20 ft W24×370 weighs about 7,400 pounds.
How far can a W24×370 span?
It depends on the load. Braced along its length, it carries 173.0 kips per foot of factored load at 14 ft and 6.92 kips per foot at 70 ft; the load table has the spans in between. Floor beams are often 42 to 56 ft for this depth (span-to-depth ratios of about 18 to 24), where deflection usually governs.
Is a W24×370 a compact section?
Yes. Its flanges (bf/2tf = 2.51) and web (h/tw = 14.2) are both compact for bending in 50 ksi steel.