W33×169 Steel Beam
A W33×169 is a wide flange steel beam 33.8 inches deep with 11.5-inch flanges, weighing 169 pounds per foot. In ASTM A992 steel (Fy = 50 ksi) it has a design bending strength of 2,359 kip-ft (LRFD) when its compression flange is braced, and a design shear strength of 679 kips.
Design a W33×169 beam Opens a 51 ft span in the free beam designer.
W33×169 dimensions
| Dimension | Value |
|---|---|
| Depth, d | 33.8 in |
| Flange width, bf | 11.5 in |
| Flange thickness, tf | 1.22 in |
| Web thickness, tw | 0.670 in |
| Distance to web toe of fillet, kdes | 1.92 in |
| Distance between flange centroids, ho | 32.58 in |
| Cross-sectional area, A | 49.5 in2 |
| Weight | 169 lb/ft |
Dimensions are AISC design values. Detailing dimensions are rounded to the nearest 1/16 in.
W33×169 section properties
| Property | Strong axis (x) | Weak axis (y) |
|---|---|---|
| Moment of inertia, I | 9290 in4 | 310 in4 |
| Elastic section modulus, S | 549 in3 | 53.9 in3 |
| Plastic section modulus, Z | 629 in3 | 84.4 in3 |
| Radius of gyration, r | 13.7 in | 2.50 in |
| Torsion and slenderness | Value |
|---|---|
| Torsional constant, J | 17.7 in4 |
| Warping constant, Cw | 82400 in6 |
| Effective radius of gyration, rts | 3.03 in |
| Flange slenderness, bf/2tf | 4.71 |
| Web slenderness, h/tw | 44.7 |
W33×169 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 = 2,359 kip-ft | Mn/Ω = 1,569 kip-ft |
| Shear | φVn = 679 kips | Vn/Ω = 453 kips |
If the compression flange isn't braced, the beam can buckle sideways before it yields. Up to Lp = 8.8 ft between braces it keeps its full strength; past Lr = 26.7 ft it buckles elastically. With uniform moment between braces (Cb = 1.0):
| Unbraced length, Lb | φMn (LRFD) | Mn/Ω (ASD) |
|---|---|---|
| Braced | 2,359 kip-ft | 1,569 kip-ft |
| 5 ft | 2,359 kip-ft | 1,569 kip-ft |
| 8.8 ft (Lp) | 2,359 kip-ft | 1,569 kip-ft |
| 10 ft | 2,299 kip-ft | 1,529 kip-ft |
| 15 ft | 2,042 kip-ft | 1,359 kip-ft |
| 20 ft | 1,786 kip-ft | 1,188 kip-ft |
| 25 ft | 1,530 kip-ft | 1,018 kip-ft |
| 26.7 ft (Lr) | 1,439 kip-ft | 958 kip-ft |
| 30 ft | 1,209 kip-ft | 805 kip-ft |
| 35 ft | 968 kip-ft | 644 kip-ft |
| 40 ft | 806 kip-ft | 536 kip-ft |
| 45 ft | 691 kip-ft | 459 kip-ft |
| 50 ft | 604 kip-ft | 402 kip-ft |
| 55 ft | 537 kip-ft | 357 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.
W33×169 load table by span
The largest uniform load a simply supported W33×169 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 0.169 kips per foot.
| Span | Factored load (LRFD) | Allowable load (ASD) | Load at span/360 | Load at span/240 |
|---|---|---|---|---|
| 17 ft | 65.3 | 43.4 | 81.2 | 121.9 |
| 19 ft | 52.3 | 34.8 | 58.2 | 87.3 |
| 21 ft | 42.8 | 28.5 | 43.1 | 64.6 |
| 23 ft | 35.7 | 23.7 | 32.8 | 49.2 |
| 25 ft | 30.2 | 20.1 | 25.5 | 38.3 |
| 27 ft | 25.9 | 17.2 | 20.3 | 30.4 |
| 29 ft | 22.4 | 14.9 | 16.4 | 24.5 |
| 31 ft | 19.6 | 13.1 | 13.4 | 20.1 |
| 33 ft | 17.3 | 11.5 | 11.1 | 16.7 |
| 35 ft | 15.4 | 10.2 | 9.31 | 14.0 |
| 37 ft | 13.8 | 9.17 | 7.88 | 11.8 |
| 39 ft | 12.4 | 8.25 | 6.73 | 10.1 |
| 41 ft | 11.2 | 7.47 | 5.79 | 8.69 |
| 43 ft | 10.2 | 6.79 | 5.02 | 7.53 |
| 45 ft | 9.32 | 6.20 | 4.38 | 6.57 |
| 47 ft | 8.54 | 5.68 | 3.84 | 5.77 |
| 49 ft | 7.86 | 5.23 | 3.39 | 5.09 |
| 51 ft | 7.25 | 4.83 | 3.01 | 4.51 |
| 53 ft | 6.72 | 4.47 | 2.68 | 4.02 |
| 55 ft | 6.24 | 4.15 | 2.40 | 3.60 |
| 57 ft | 5.81 | 3.86 | 2.16 | 3.23 |
| 59 ft | 5.42 | 3.61 | 1.94 | 2.92 |
| 61 ft | 5.07 | 3.37 | 1.76 | 2.64 |
| 63 ft | 4.75 | 3.16 | 1.60 | 2.39 |
| 65 ft | 4.47 | 2.97 | 1.45 | 2.18 |
| 67 ft | 4.20 | 2.80 | 1.33 | 1.99 |
| 69 ft | 3.96 | 2.64 | 1.21 | 1.82 |
| 71 ft | 3.74 | 2.49 | 1.12 | 1.67 |
| 73 ft | 3.54 | 2.36 | 1.03 | 1.54 |
| 75 ft | 3.35 | 2.23 | 0.95 | 1.42 |
| 77 ft | 3.18 | 2.12 | 0.87 | 1.31 |
| 79 ft | 3.02 | 2.01 | 0.81 | 1.21 |
| 81 ft | 2.88 | 1.91 | 0.75 | 1.13 |
| 83 ft | 2.74 | 1.82 | 0.70 | 1.05 |
- 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 W33×169 carries a factored load of 7.25 kips per foot (LRFD) or an allowable load of 4.83 kips per foot (ASD). A live load of 3.01 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.
W33×169 questions
What does W33×169 mean?
W means a wide flange shape. 33 is its nominal depth in inches (the actual depth is 33.8 in) and 169 is its weight in pounds per foot.
How much does a W33×169 weigh?
169 pounds per foot, so a 20 ft W33×169 weighs about 3,380 pounds.
How far can a W33×169 span?
It depends on the load. Braced along its length, it carries 65.3 kips per foot of factored load at 17 ft and 2.74 kips per foot at 83 ft; the load table has the spans in between. Floor beams are often 51 to 68 ft for this depth (span-to-depth ratios of about 18 to 24), where deflection usually governs.
Is a W33×169 a compact section?
Yes. Its flanges (bf/2tf = 4.71) and web (h/tw = 44.7) are both compact for bending in 50 ksi steel.