W24×279 Steel Beam
A W24×279 is a wide flange steel beam 26.7 inches deep with 13.3-inch flanges, weighing 279 pounds per foot. In ASTM A992 steel (Fy = 50 ksi) it has a design bending strength of 3,131 kip-ft (LRFD) when its compression flange is braced, and a design shear strength of 929 kips.
Design a W24×279 beam Opens a 41 ft span in the free beam designer.
W24×279 dimensions
| Dimension | Value |
|---|---|
| Depth, d | 26.7 in |
| Flange width, bf | 13.3 in |
| Flange thickness, tf | 2.09 in |
| Web thickness, tw | 1.16 in |
| Distance to web toe of fillet, kdes | 2.59 in |
| Distance between flange centroids, ho | 24.61 in |
| Cross-sectional area, A | 82.0 in2 |
| Weight | 279 lb/ft |
Dimensions are AISC design values. Detailing dimensions are rounded to the nearest 1/16 in.
W24×279 section properties
| Property | Strong axis (x) | Weak axis (y) |
|---|---|---|
| Moment of inertia, I | 9600 in4 | 823 in4 |
| Elastic section modulus, S | 718 in3 | 124 in3 |
| Plastic section modulus, Z | 835 in3 | 193 in3 |
| Radius of gyration, r | 10.8 in | 3.17 in |
| Torsion and slenderness | Value |
|---|---|
| Torsional constant, J | 90.5 in4 |
| Warping constant, Cw | 125000 in6 |
| Effective radius of gyration, rts | 3.76 in |
| Flange slenderness, bf/2tf | 3.18 |
| Web slenderness, h/tw | 18.6 |
W24×279 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 = 3,131 kip-ft | Mn/Ω = 2,083 kip-ft |
| Shear | φVn = 929 kips | Vn/Ω = 619 kips |
If the compression flange isn't braced, the beam can buckle sideways before it yields. Up to Lp = 11.2 ft between braces it keeps its full strength; past Lr = 53.4 ft it buckles elastically. With uniform moment between braces (Cb = 1.0):
| Unbraced length, Lb | φMn (LRFD) | Mn/Ω (ASD) |
|---|---|---|
| Braced | 3,131 kip-ft | 2,083 kip-ft |
| 10 ft | 3,131 kip-ft | 2,083 kip-ft |
| 11.2 ft (Lp) | 3,131 kip-ft | 2,083 kip-ft |
| 20 ft | 2,871 kip-ft | 1,910 kip-ft |
| 30 ft | 2,576 kip-ft | 1,714 kip-ft |
| 40 ft | 2,280 kip-ft | 1,517 kip-ft |
| 50 ft | 1,985 kip-ft | 1,321 kip-ft |
| 53.4 ft (Lr) | 1,885 kip-ft | 1,254 kip-ft |
| 60 ft | 1,662 kip-ft | 1,106 kip-ft |
| 70 ft | 1,413 kip-ft | 940 kip-ft |
| 80 ft | 1,229 kip-ft | 818 kip-ft |
| 90 ft | 1,088 kip-ft | 724 kip-ft |
| 100 ft | 977 kip-ft | 650 kip-ft |
| 110 ft | 886 kip-ft | 589 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.
W24×279 load table by span
The largest uniform load a simply supported W24×279 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 0.279 kips per foot.
| Span | Factored load (LRFD) | Allowable load (ASD) | Load at span/360 | Load at span/240 |
|---|---|---|---|---|
| 13 ft | 142.9* | 95.3* | 187.7 | 281.6 |
| 15 ft | 111.3 | 74.1 | 122.2 | 183.3 |
| 17 ft | 86.7 | 57.7 | 83.9 | 125.9 |
| 19 ft | 69.4 | 46.2 | 60.1 | 90.2 |
| 21 ft | 56.8 | 37.8 | 44.5 | 66.8 |
| 23 ft | 47.4 | 31.5 | 33.9 | 50.8 |
| 25 ft | 40.1 | 26.7 | 26.4 | 39.6 |
| 27 ft | 34.4 | 22.9 | 21.0 | 31.4 |
| 29 ft | 29.8 | 19.8 | 16.9 | 25.4 |
| 31 ft | 26.1 | 17.3 | 13.8 | 20.8 |
| 33 ft | 23.0 | 15.3 | 11.5 | 17.2 |
| 35 ft | 20.4 | 13.6 | 9.62 | 14.4 |
| 37 ft | 18.3 | 12.2 | 8.14 | 12.2 |
| 39 ft | 16.5 | 11.0 | 6.95 | 10.4 |
| 41 ft | 14.9 | 9.91 | 5.98 | 8.98 |
| 43 ft | 13.5 | 9.01 | 5.19 | 7.78 |
| 45 ft | 12.4 | 8.23 | 4.53 | 6.79 |
| 47 ft | 11.3 | 7.54 | 3.97 | 5.96 |
| 49 ft | 10.4 | 6.94 | 3.51 | 5.26 |
| 51 ft | 9.63 | 6.41 | 3.11 | 4.66 |
| 53 ft | 8.92 | 5.93 | 2.77 | 4.16 |
| 55 ft | 8.28 | 5.51 | 2.48 | 3.72 |
| 57 ft | 7.71 | 5.13 | 2.23 | 3.34 |
| 59 ft | 7.20 | 4.79 | 2.01 | 3.01 |
| 61 ft | 6.73 | 4.48 | 1.82 | 2.73 |
| 63 ft | 6.31 | 4.20 | 1.65 | 2.47 |
| 65 ft | 5.93 | 3.94 | 1.50 | 2.25 |
| 67 ft | 5.58 | 3.71 | 1.37 | 2.06 |
- 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 41 ft span, a W24×279 carries a factored load of 14.9 kips per foot (LRFD) or an allowable load of 9.91 kips per foot (ASD). A live load of 5.98 kips per foot would deflect it span/360, which is 1.37 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.
W24×279 questions
What does W24×279 mean?
W means a wide flange shape. 24 is its nominal depth in inches (the actual depth is 26.7 in) and 279 is its weight in pounds per foot.
How much does a W24×279 weigh?
279 pounds per foot, so a 20 ft W24×279 weighs about 5,580 pounds.
How far can a W24×279 span?
It depends on the load. Braced along its length, it carries 142.9 kips per foot of factored load at 13 ft and 5.58 kips per foot at 67 ft; the load table has the spans in between. Floor beams are often 40 to 53 ft for this depth (span-to-depth ratios of about 18 to 24), where deflection usually governs.
Is a W24×279 a compact section?
Yes. Its flanges (bf/2tf = 3.18) and web (h/tw = 18.6) are both compact for bending in 50 ksi steel.