W33×130 Steel Beam
A W33×130 is a wide flange steel beam 33.1 inches deep with 11.5-inch flanges, weighing 130 pounds per foot. In ASTM A992 steel (Fy = 50 ksi) it has a design bending strength of 1,751 kip-ft (LRFD) when its compression flange is braced, and a design shear strength of 576 kips.
Design a W33×130 beam Opens a 51 ft span in the free beam designer.
W33×130 dimensions
| Dimension | Value |
|---|---|
| Depth, d | 33.1 in |
| Flange width, bf | 11.5 in |
| Flange thickness, tf | 0.855 in |
| Web thickness, tw | 0.580 in |
| Distance to web toe of fillet, kdes | 1.56 in |
| Distance between flange centroids, ho | 32.25 in |
| Cross-sectional area, A | 38.3 in2 |
| Weight | 130 lb/ft |
Dimensions are AISC design values. Detailing dimensions are rounded to the nearest 1/16 in.
W33×130 section properties
| Property | Strong axis (x) | Weak axis (y) |
|---|---|---|
| Moment of inertia, I | 6710 in4 | 218 in4 |
| Elastic section modulus, S | 406 in3 | 37.9 in3 |
| Plastic section modulus, Z | 467 in3 | 59.5 in3 |
| Radius of gyration, r | 13.2 in | 2.39 in |
| Torsion and slenderness | Value |
|---|---|
| Torsional constant, J | 7.37 in4 |
| Warping constant, Cw | 56600 in6 |
| Effective radius of gyration, rts | 2.94 in |
| Flange slenderness, bf/2tf | 6.73 |
| Web slenderness, h/tw | 51.7 |
W33×130 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 = 1,751 kip-ft | Mn/Ω = 1,165 kip-ft |
| Shear | φVn = 576 kips | Vn/Ω = 384 kips |
If the compression flange isn't braced, the beam can buckle sideways before it yields. Up to Lp = 8.4 ft between braces it keeps its full strength; past Lr = 24.3 ft it buckles elastically. With uniform moment between braces (Cb = 1.0):
| Unbraced length, Lb | φMn (LRFD) | Mn/Ω (ASD) |
|---|---|---|
| Braced | 1,751 kip-ft | 1,165 kip-ft |
| 5 ft | 1,751 kip-ft | 1,165 kip-ft |
| 8.4 ft (Lp) | 1,751 kip-ft | 1,165 kip-ft |
| 10 ft | 1,684 kip-ft | 1,120 kip-ft |
| 15 ft | 1,467 kip-ft | 976 kip-ft |
| 20 ft | 1,250 kip-ft | 832 kip-ft |
| 24.3 ft (Lr) | 1,064 kip-ft | 708 kip-ft |
| 25 ft | 1,011 kip-ft | 673 kip-ft |
| 30 ft | 749 kip-ft | 498 kip-ft |
| 35 ft | 588 kip-ft | 392 kip-ft |
| 40 ft | 482 kip-ft | 321 kip-ft |
| 45 ft | 407 kip-ft | 271 kip-ft |
| 50 ft | 352 kip-ft | 234 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.
W33×130 load table by span
The largest uniform load a simply supported W33×130 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 0.130 kips per foot.
| Span | Factored load (LRFD) | Allowable load (ASD) | Load at span/360 | Load at span/240 |
|---|---|---|---|---|
| 17 ft | 48.5 | 32.3 | 58.7 | 88.0 |
| 19 ft | 38.8 | 25.8 | 42.0 | 63.0 |
| 21 ft | 31.8 | 21.1 | 31.1 | 46.7 |
| 23 ft | 26.5 | 17.6 | 23.7 | 35.5 |
| 25 ft | 22.4 | 14.9 | 18.5 | 27.7 |
| 27 ft | 19.2 | 12.8 | 14.6 | 22.0 |
| 29 ft | 16.7 | 11.1 | 11.8 | 17.7 |
| 31 ft | 14.6 | 9.70 | 9.68 | 14.5 |
| 33 ft | 12.9 | 8.56 | 8.02 | 12.0 |
| 35 ft | 11.4 | 7.61 | 6.72 | 10.1 |
| 37 ft | 10.2 | 6.81 | 5.69 | 8.54 |
| 39 ft | 9.21 | 6.13 | 4.86 | 7.29 |
| 41 ft | 8.33 | 5.55 | 4.18 | 6.27 |
| 43 ft | 7.58 | 5.04 | 3.63 | 5.44 |
| 45 ft | 6.92 | 4.60 | 3.16 | 4.75 |
| 47 ft | 6.34 | 4.22 | 2.78 | 4.16 |
| 49 ft | 5.84 | 3.88 | 2.45 | 3.68 |
| 51 ft | 5.39 | 3.58 | 2.17 | 3.26 |
| 53 ft | 4.99 | 3.32 | 1.94 | 2.90 |
| 55 ft | 4.63 | 3.08 | 1.73 | 2.60 |
| 57 ft | 4.31 | 2.87 | 1.56 | 2.33 |
| 59 ft | 4.02 | 2.68 | 1.40 | 2.11 |
| 61 ft | 3.77 | 2.51 | 1.27 | 1.91 |
| 63 ft | 3.53 | 2.35 | 1.15 | 1.73 |
| 65 ft | 3.32 | 2.21 | 1.05 | 1.57 |
| 67 ft | 3.12 | 2.08 | 0.96 | 1.44 |
| 69 ft | 2.94 | 1.96 | 0.88 | 1.32 |
| 71 ft | 2.78 | 1.85 | 0.81 | 1.21 |
| 73 ft | 2.63 | 1.75 | 0.74 | 1.11 |
| 75 ft | 2.49 | 1.66 | 0.68 | 1.03 |
| 77 ft | 2.36 | 1.57 | 0.63 | 0.95 |
| 79 ft | 2.24 | 1.49 | 0.58 | 0.88 |
| 81 ft | 2.14 | 1.42 | 0.54 | 0.81 |
| 83 ft | 2.03 | 1.35 | 0.50 | 0.76 |
- 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 51 ft span, a W33×130 carries a factored load of 5.39 kips per foot (LRFD) or an allowable load of 3.58 kips per foot (ASD). A live load of 2.17 kips per foot would deflect it span/360, which is 1.70 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.
W33×130 questions
What does W33×130 mean?
W means a wide flange shape. 33 is its nominal depth in inches (the actual depth is 33.1 in) and 130 is its weight in pounds per foot.
How much does a W33×130 weigh?
130 pounds per foot, so a 20 ft W33×130 weighs about 2,600 pounds.
How far can a W33×130 span?
It depends on the load. Braced along its length, it carries 48.5 kips per foot of factored load at 17 ft and 2.03 kips per foot at 83 ft; the load table has the spans in between. Floor beams are often 50 to 66 ft for this depth (span-to-depth ratios of about 18 to 24), where deflection usually governs.
Is a W33×130 a compact section?
Yes. Its flanges (bf/2tf = 6.73) and web (h/tw = 51.7) are both compact for bending in 50 ksi steel.