W30×261 Steel Beam
A W30×261 is a wide flange steel beam 31.6 inches deep with 15.2-inch flanges, weighing 261 pounds per foot. In ASTM A992 steel (Fy = 50 ksi) it has a design bending strength of 3,536 kip-ft (LRFD) when its compression flange is braced, and a design shear strength of 882 kips.
Design a W30×261 beam Opens a 48 ft span in the free beam designer.
W30×261 dimensions
| Dimension | Value |
|---|---|
| Depth, d | 31.6 in |
| Flange width, bf | 15.2 in |
| Flange thickness, tf | 1.65 in |
| Web thickness, tw | 0.930 in |
| Distance to web toe of fillet, kdes | 2.44 in |
| Distance between flange centroids, ho | 29.95 in |
| Cross-sectional area, A | 76.9 in2 |
| Weight | 261 lb/ft |
Dimensions are AISC design values. Detailing dimensions are rounded to the nearest 1/16 in.
W30×261 section properties
| Property | Strong axis (x) | Weak axis (y) |
|---|---|---|
| Moment of inertia, I | 13100 in4 | 959 in4 |
| Elastic section modulus, S | 829 in3 | 127 in3 |
| Plastic section modulus, Z | 943 in3 | 196 in3 |
| Radius of gyration, r | 13.1 in | 3.53 in |
| Torsion and slenderness | Value |
|---|---|
| Torsional constant, J | 54.1 in4 |
| Warping constant, Cw | 215000 in6 |
| Effective radius of gyration, rts | 4.16 in |
| Flange slenderness, bf/2tf | 4.59 |
| Web slenderness, h/tw | 28.7 |
W30×261 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 = 3,536 kip-ft | Mn/Ω = 2,353 kip-ft |
| Shear | φVn = 882 kips | Vn/Ω = 588 kips |
If the compression flange isn't braced, the beam can buckle sideways before it yields. Up to Lp = 12.5 ft between braces it keeps its full strength; past Lr = 43.4 ft it buckles elastically. With uniform moment between braces (Cb = 1.0):
| Unbraced length, Lb | φMn (LRFD) | Mn/Ω (ASD) |
|---|---|---|
| Braced | 3,536 kip-ft | 2,353 kip-ft |
| 10 ft | 3,536 kip-ft | 2,353 kip-ft |
| 12.5 ft (Lp) | 3,536 kip-ft | 2,353 kip-ft |
| 20 ft | 3,205 kip-ft | 2,132 kip-ft |
| 30 ft | 2,765 kip-ft | 1,840 kip-ft |
| 40 ft | 2,326 kip-ft | 1,547 kip-ft |
| 43.4 ft (Lr) | 2,176 kip-ft | 1,448 kip-ft |
| 50 ft | 1,823 kip-ft | 1,213 kip-ft |
| 60 ft | 1,467 kip-ft | 976 kip-ft |
| 70 ft | 1,230 kip-ft | 818 kip-ft |
| 80 ft | 1,060 kip-ft | 705 kip-ft |
| 90 ft | 932 kip-ft | 620 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.
W30×261 load table by span
The largest uniform load a simply supported W30×261 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 0.261 kips per foot.
| Span | Factored load (LRFD) | Allowable load (ASD) | Load at span/360 | Load at span/240 |
|---|---|---|---|---|
| 16 ft | 110.2* | 73.5* | 137.4 | 206.1 |
| 18 ft | 87.3 | 58.1 | 96.5 | 144.8 |
| 20 ft | 70.7 | 47.1 | 70.4 | 105.5 |
| 22 ft | 58.5 | 38.9 | 52.9 | 79.3 |
| 24 ft | 49.1 | 32.7 | 40.7 | 61.1 |
| 26 ft | 41.8 | 27.8 | 32.0 | 48.0 |
| 28 ft | 36.1 | 24.0 | 25.6 | 38.5 |
| 30 ft | 31.4 | 20.9 | 20.8 | 31.3 |
| 32 ft | 27.6 | 18.4 | 17.2 | 25.8 |
| 34 ft | 24.5 | 16.3 | 14.3 | 21.5 |
| 36 ft | 21.8 | 14.5 | 12.1 | 18.1 |
| 38 ft | 19.6 | 13.0 | 10.3 | 15.4 |
| 40 ft | 17.7 | 11.8 | 8.79 | 13.2 |
| 42 ft | 16.0 | 10.7 | 7.60 | 11.4 |
| 44 ft | 14.6 | 9.72 | 6.61 | 9.91 |
| 46 ft | 13.4 | 8.90 | 5.78 | 8.67 |
| 48 ft | 12.3 | 8.17 | 5.09 | 7.63 |
| 50 ft | 11.3 | 7.53 | 4.50 | 6.75 |
| 52 ft | 10.5 | 6.96 | 4.00 | 6.00 |
| 54 ft | 9.70 | 6.45 | 3.57 | 5.36 |
| 56 ft | 9.02 | 6.00 | 3.20 | 4.81 |
| 58 ft | 8.41 | 5.60 | 2.88 | 4.33 |
| 60 ft | 7.86 | 5.23 | 2.61 | 3.91 |
| 62 ft | 7.36 | 4.90 | 2.36 | 3.54 |
| 64 ft | 6.91 | 4.60 | 2.15 | 3.22 |
| 66 ft | 6.49 | 4.32 | 1.96 | 2.94 |
| 68 ft | 6.12 | 4.07 | 1.79 | 2.68 |
| 70 ft | 5.77 | 3.84 | 1.64 | 2.46 |
| 72 ft | 5.46 | 3.63 | 1.51 | 2.26 |
| 74 ft | 5.17 | 3.44 | 1.39 | 2.08 |
| 76 ft | 4.90 | 3.26 | 1.28 | 1.92 |
| 78 ft | 4.65 | 3.09 | 1.19 | 1.78 |
- 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 48 ft span, a W30×261 carries a factored load of 12.3 kips per foot (LRFD) or an allowable load of 8.17 kips per foot (ASD). A live load of 5.09 kips per foot would deflect it span/360, which is 1.60 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.
W30×261 questions
What does W30×261 mean?
W means a wide flange shape. 30 is its nominal depth in inches (the actual depth is 31.6 in) and 261 is its weight in pounds per foot.
How much does a W30×261 weigh?
261 pounds per foot, so a 20 ft W30×261 weighs about 5,220 pounds.
How far can a W30×261 span?
It depends on the load. Braced along its length, it carries 110.2 kips per foot of factored load at 16 ft and 4.65 kips per foot at 78 ft; the load table has the spans in between. Floor beams are often 47 to 63 ft for this depth (span-to-depth ratios of about 18 to 24), where deflection usually governs.
Is a W30×261 a compact section?
Yes. Its flanges (bf/2tf = 4.59) and web (h/tw = 28.7) are both compact for bending in 50 ksi steel.