W27×161 Steel Beam
A W27×161 is a wide flange steel beam 27.6 inches deep with 14-inch flanges, weighing 161 pounds per foot. In ASTM A992 steel (Fy = 50 ksi) it has a design bending strength of 1,931 kip-ft (LRFD) when its compression flange is braced, and a design shear strength of 546 kips.
Design a W27×161 beam Opens a 42 ft span in the free beam designer.
W27×161 dimensions
| Dimension | Value |
|---|---|
| Depth, d | 27.6 in |
| Flange width, bf | 14.0 in |
| Flange thickness, tf | 1.08 in |
| Web thickness, tw | 0.660 in |
| Distance to web toe of fillet, kdes | 1.87 in |
| Distance between flange centroids, ho | 26.52 in |
| Cross-sectional area, A | 47.6 in2 |
| Weight | 161 lb/ft |
Dimensions are AISC design values. Detailing dimensions are rounded to the nearest 1/16 in.
W27×161 section properties
| Property | Strong axis (x) | Weak axis (y) |
|---|---|---|
| Moment of inertia, I | 6310 in4 | 497 in4 |
| Elastic section modulus, S | 458 in3 | 70.9 in3 |
| Plastic section modulus, Z | 515 in3 | 109 in3 |
| Radius of gyration, r | 11.5 in | 3.23 in |
| Torsion and slenderness | Value |
|---|---|
| Torsional constant, J | 15.1 in4 |
| Warping constant, Cw | 87300 in6 |
| Effective radius of gyration, rts | 3.79 in |
| Flange slenderness, bf/2tf | 6.49 |
| Web slenderness, h/tw | 36.1 |
W27×161 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 = 1,931 kip-ft | Mn/Ω = 1,285 kip-ft |
| Shear | φVn = 546 kips | Vn/Ω = 364 kips |
If the compression flange isn't braced, the beam can buckle sideways before it yields. Up to Lp = 11.4 ft between braces it keeps its full strength; past Lr = 34.7 ft it buckles elastically. With uniform moment between braces (Cb = 1.0):
| Unbraced length, Lb | φMn (LRFD) | Mn/Ω (ASD) |
|---|---|---|
| Braced | 1,931 kip-ft | 1,285 kip-ft |
| 10 ft | 1,931 kip-ft | 1,285 kip-ft |
| 11.4 ft (Lp) | 1,931 kip-ft | 1,285 kip-ft |
| 20 ft | 1,662 kip-ft | 1,106 kip-ft |
| 30 ft | 1,349 kip-ft | 898 kip-ft |
| 34.7 ft (Lr) | 1,202 kip-ft | 800 kip-ft |
| 40 ft | 981 kip-ft | 652 kip-ft |
| 50 ft | 727 kip-ft | 484 kip-ft |
| 60 ft | 578 kip-ft | 385 kip-ft |
| 70 ft | 481 kip-ft | 320 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.
W27×161 load table by span
The largest uniform load a simply supported W27×161 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 0.161 kips per foot.
| Span | Factored load (LRFD) | Allowable load (ASD) | Load at span/360 | Load at span/240 |
|---|---|---|---|---|
| 14 ft | 78.1* | 52.0* | 98.8 | 148.2 |
| 16 ft | 60.4 | 40.2 | 66.2 | 99.3 |
| 18 ft | 47.7 | 31.7 | 46.5 | 69.7 |
| 20 ft | 38.6 | 25.7 | 33.9 | 50.8 |
| 22 ft | 31.9 | 21.2 | 25.5 | 38.2 |
| 24 ft | 26.8 | 17.8 | 19.6 | 29.4 |
| 26 ft | 22.9 | 15.2 | 15.4 | 23.1 |
| 28 ft | 19.7 | 13.1 | 12.3 | 18.5 |
| 30 ft | 17.2 | 11.4 | 10.0 | 15.1 |
| 32 ft | 15.1 | 10.0 | 8.27 | 12.4 |
| 34 ft | 13.4 | 8.89 | 6.90 | 10.3 |
| 36 ft | 11.9 | 7.93 | 5.81 | 8.72 |
| 38 ft | 10.7 | 7.12 | 4.94 | 7.41 |
| 40 ft | 9.66 | 6.42 | 4.24 | 6.35 |
| 42 ft | 8.76 | 5.83 | 3.66 | 5.49 |
| 44 ft | 7.98 | 5.31 | 3.18 | 4.77 |
| 46 ft | 7.30 | 4.86 | 2.79 | 4.18 |
| 48 ft | 6.71 | 4.46 | 2.45 | 3.68 |
| 50 ft | 6.18 | 4.11 | 2.17 | 3.25 |
| 52 ft | 5.71 | 3.80 | 1.93 | 2.89 |
| 54 ft | 5.30 | 3.53 | 1.72 | 2.58 |
| 56 ft | 4.93 | 3.28 | 1.54 | 2.32 |
| 58 ft | 4.59 | 3.06 | 1.39 | 2.08 |
| 60 ft | 4.29 | 2.86 | 1.26 | 1.88 |
| 62 ft | 4.02 | 2.67 | 1.14 | 1.71 |
| 64 ft | 3.77 | 2.51 | 1.03 | 1.55 |
| 66 ft | 3.55 | 2.36 | 0.94 | 1.41 |
| 68 ft | 3.34 | 2.22 | 0.86 | 1.29 |
- 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 42 ft span, a W27×161 carries a factored load of 8.76 kips per foot (LRFD) or an allowable load of 5.83 kips per foot (ASD). A live load of 3.66 kips per foot would deflect it span/360, which is 1.40 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.
W27×161 questions
What does W27×161 mean?
W means a wide flange shape. 27 is its nominal depth in inches (the actual depth is 27.6 in) and 161 is its weight in pounds per foot.
How much does a W27×161 weigh?
161 pounds per foot, so a 20 ft W27×161 weighs about 3,220 pounds.
How far can a W27×161 span?
It depends on the load. Braced along its length, it carries 78.1 kips per foot of factored load at 14 ft and 3.34 kips per foot at 68 ft; the load table has the spans in between. Floor beams are often 41 to 55 ft for this depth (span-to-depth ratios of about 18 to 24), where deflection usually governs.
Is a W27×161 a compact section?
Yes. Its flanges (bf/2tf = 6.49) and web (h/tw = 36.1) are both compact for bending in 50 ksi steel.