W30×148 Steel Beam
A W30×148 is a wide flange steel beam 30.7 inches deep with 10.5-inch flanges, weighing 148 pounds per foot. In ASTM A992 steel (Fy = 50 ksi) it has a design bending strength of 1,875 kip-ft (LRFD) when its compression flange is braced, and a design shear strength of 599 kips.
Design a W30×148 beam Opens a 47 ft span in the free beam designer.
W30×148 dimensions
| Dimension | Value |
|---|---|
| Depth, d | 30.7 in |
| Flange width, bf | 10.5 in |
| Flange thickness, tf | 1.18 in |
| Web thickness, tw | 0.650 in |
| Distance to web toe of fillet, kdes | 1.83 in |
| Distance between flange centroids, ho | 29.52 in |
| Cross-sectional area, A | 43.5 in2 |
| Weight | 148 lb/ft |
Dimensions are AISC design values. Detailing dimensions are rounded to the nearest 1/16 in.
W30×148 section properties
| Property | Strong axis (x) | Weak axis (y) |
|---|---|---|
| Moment of inertia, I | 6680 in4 | 227 in4 |
| Elastic section modulus, S | 436 in3 | 43.3 in3 |
| Plastic section modulus, Z | 500 in3 | 68.0 in3 |
| Radius of gyration, r | 12.4 in | 2.28 in |
| Torsion and slenderness | Value |
|---|---|
| Torsional constant, J | 14.5 in4 |
| Warping constant, Cw | 49400 in6 |
| Effective radius of gyration, rts | 2.77 in |
| Flange slenderness, bf/2tf | 4.44 |
| Web slenderness, h/tw | 41.6 |
W30×148 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 = 1,875 kip-ft | Mn/Ω = 1,248 kip-ft |
| Shear | φVn = 599 kips | Vn/Ω = 399 kips |
If the compression flange isn't braced, the beam can buckle sideways before it yields. Up to Lp = 8.1 ft between braces it keeps its full strength; past Lr = 24.9 ft it buckles elastically. With uniform moment between braces (Cb = 1.0):
| Unbraced length, Lb | φMn (LRFD) | Mn/Ω (ASD) |
|---|---|---|
| Braced | 1,875 kip-ft | 1,248 kip-ft |
| 5 ft | 1,875 kip-ft | 1,248 kip-ft |
| 8.1 ft (Lp) | 1,875 kip-ft | 1,248 kip-ft |
| 10 ft | 1,791 kip-ft | 1,191 kip-ft |
| 15 ft | 1,574 kip-ft | 1,047 kip-ft |
| 20 ft | 1,358 kip-ft | 903 kip-ft |
| 24.9 ft (Lr) | 1,145 kip-ft | 762 kip-ft |
| 25 ft (Lr) | 1,138 kip-ft | 757 kip-ft |
| 30 ft | 874 kip-ft | 581 kip-ft |
| 35 ft | 708 kip-ft | 471 kip-ft |
| 40 ft | 595 kip-ft | 396 kip-ft |
| 45 ft | 513 kip-ft | 342 kip-ft |
| 50 ft | 452 kip-ft | 301 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.
W30×148 load table by span
The largest uniform load a simply supported W30×148 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 0.148 kips per foot.
| Span | Factored load (LRFD) | Allowable load (ASD) | Load at span/360 | Load at span/240 |
|---|---|---|---|---|
| 15 ft | 66.7 | 44.4 | 85.0 | 127.6 |
| 17 ft | 51.9 | 34.5 | 58.4 | 87.6 |
| 19 ft | 41.6 | 27.6 | 41.8 | 62.8 |
| 21 ft | 34.0 | 22.6 | 31.0 | 46.5 |
| 23 ft | 28.4 | 18.9 | 23.6 | 35.4 |
| 25 ft | 24.0 | 16.0 | 18.4 | 27.6 |
| 27 ft | 20.6 | 13.7 | 14.6 | 21.9 |
| 29 ft | 17.8 | 11.9 | 11.8 | 17.7 |
| 31 ft | 15.6 | 10.4 | 9.63 | 14.5 |
| 33 ft | 13.8 | 9.16 | 7.99 | 12.0 |
| 35 ft | 12.2 | 8.15 | 6.69 | 10.0 |
| 37 ft | 11.0 | 7.29 | 5.67 | 8.50 |
| 39 ft | 9.86 | 6.56 | 4.84 | 7.26 |
| 41 ft | 8.92 | 5.94 | 4.16 | 6.25 |
| 43 ft | 8.11 | 5.40 | 3.61 | 5.41 |
| 45 ft | 7.41 | 4.93 | 3.15 | 4.72 |
| 47 ft | 6.79 | 4.52 | 2.76 | 4.15 |
| 49 ft | 6.25 | 4.16 | 2.44 | 3.66 |
| 51 ft | 5.77 | 3.84 | 2.16 | 3.25 |
| 53 ft | 5.34 | 3.55 | 1.93 | 2.89 |
| 55 ft | 4.96 | 3.30 | 1.72 | 2.59 |
| 57 ft | 4.62 | 3.07 | 1.55 | 2.32 |
| 59 ft | 4.31 | 2.87 | 1.40 | 2.10 |
| 61 ft | 4.03 | 2.68 | 1.26 | 1.90 |
| 63 ft | 3.78 | 2.51 | 1.15 | 1.72 |
| 65 ft | 3.55 | 2.36 | 1.05 | 1.57 |
| 67 ft | 3.34 | 2.22 | 0.95 | 1.43 |
| 69 ft | 3.15 | 2.10 | 0.87 | 1.31 |
| 71 ft | 2.98 | 1.98 | 0.80 | 1.20 |
| 73 ft | 2.81 | 1.87 | 0.74 | 1.11 |
| 75 ft | 2.67 | 1.77 | 0.68 | 1.02 |
| 77 ft | 2.53 | 1.68 | 0.63 | 0.94 |
- 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 47 ft span, a W30×148 carries a factored load of 6.79 kips per foot (LRFD) or an allowable load of 4.52 kips per foot (ASD). A live load of 2.76 kips per foot would deflect it span/360, which is 1.57 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.
W30×148 questions
What does W30×148 mean?
W means a wide flange shape. 30 is its nominal depth in inches (the actual depth is 30.7 in) and 148 is its weight in pounds per foot.
How much does a W30×148 weigh?
148 pounds per foot, so a 20 ft W30×148 weighs about 2,960 pounds.
How far can a W30×148 span?
It depends on the load. Braced along its length, it carries 66.7 kips per foot of factored load at 15 ft and 2.53 kips per foot at 77 ft; the load table has the spans in between. Floor beams are often 46 to 61 ft for this depth (span-to-depth ratios of about 18 to 24), where deflection usually governs.
Is a W30×148 a compact section?
Yes. Its flanges (bf/2tf = 4.44) and web (h/tw = 41.6) are both compact for bending in 50 ksi steel.