W12×106 Steel Beam
A W12×106 is a wide flange steel beam 12.9 inches deep with 12.2-inch flanges, weighing 106 pounds per foot. In ASTM A992 steel (Fy = 50 ksi) it has a design bending strength of 615 kip-ft (LRFD) when its compression flange is braced, and a design shear strength of 236 kips.
Design a W12×106 beam Opens a 20 ft span in the free beam designer.
W12×106 dimensions
| Dimension | Value |
|---|---|
| Depth, d | 12.9 in |
| Flange width, bf | 12.2 in |
| Flange thickness, tf | 0.990 in |
| Web thickness, tw | 0.610 in |
| Distance to web toe of fillet, kdes | 1.59 in |
| Distance between flange centroids, ho | 11.91 in |
| Cross-sectional area, A | 31.2 in2 |
| Weight | 106 lb/ft |
Dimensions are AISC design values. Detailing dimensions are rounded to the nearest 1/16 in.
W12×106 section properties
| Property | Strong axis (x) | Weak axis (y) |
|---|---|---|
| Moment of inertia, I | 933 in4 | 301 in4 |
| Elastic section modulus, S | 145 in3 | 49.3 in3 |
| Plastic section modulus, Z | 164 in3 | 75.1 in3 |
| Radius of gyration, r | 5.47 in | 3.11 in |
| Torsion and slenderness | Value |
|---|---|
| Torsional constant, J | 9.13 in4 |
| Warping constant, Cw | 10700 in6 |
| Effective radius of gyration, rts | 3.52 in |
| Flange slenderness, bf/2tf | 6.17 |
| Web slenderness, h/tw | 15.9 |
W12×106 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 = 615 kip-ft | Mn/Ω = 409 kip-ft |
| Shear | φVn = 236 kips | Vn/Ω = 157 kips |
If the compression flange isn't braced, the beam can buckle sideways before it yields. Up to Lp = 11.0 ft between braces it keeps its full strength; past Lr = 50.7 ft it buckles elastically. With uniform moment between braces (Cb = 1.0):
| Unbraced length, Lb | φMn (LRFD) | Mn/Ω (ASD) |
|---|---|---|
| Braced | 615 kip-ft | 409 kip-ft |
| 10 ft | 615 kip-ft | 409 kip-ft |
| 11.0 ft (Lp) | 615 kip-ft | 409 kip-ft |
| 20 ft | 562 kip-ft | 374 kip-ft |
| 30 ft | 503 kip-ft | 334 kip-ft |
| 40 ft | 444 kip-ft | 295 kip-ft |
| 50 ft | 384 kip-ft | 256 kip-ft |
| 50.7 ft (Lr) | 381 kip-ft | 253 kip-ft |
| 60 ft | 318 kip-ft | 211 kip-ft |
| 70 ft | 270 kip-ft | 180 kip-ft |
| 80 ft | 235 kip-ft | 157 kip-ft |
| 90 ft | 209 kip-ft | 139 kip-ft |
| 100 ft | 187 kip-ft | 125 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.
W12×106 load table by span
The largest uniform load a simply supported W12×106 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 0.106 kips per foot.
| Span | Factored load (LRFD) | Allowable load (ASD) | Load at span/360 | Load at span/240 |
|---|---|---|---|---|
| 6 ft | 78.7* | 52.5* | 185.6 | 278.4 |
| 8 ft | 59.0* | 39.3* | 78.3 | 117.4 |
| 10 ft | 47.2* | 31.5* | 40.1 | 60.1 |
| 12 ft | 34.2 | 22.7 | 23.2 | 34.8 |
| 14 ft | 25.1 | 16.7 | 14.6 | 21.9 |
| 16 ft | 19.2 | 12.8 | 9.79 | 14.7 |
| 18 ft | 15.2 | 10.1 | 6.87 | 10.3 |
| 20 ft | 12.3 | 8.18 | 5.01 | 7.52 |
| 22 ft | 10.2 | 6.76 | 3.76 | 5.65 |
| 24 ft | 8.54 | 5.68 | 2.90 | 4.35 |
| 26 ft | 7.28 | 4.84 | 2.28 | 3.42 |
| 28 ft | 6.28 | 4.18 | 1.83 | 2.74 |
| 30 ft | 5.47 | 3.64 | 1.48 | 2.23 |
| 32 ft | 4.80 | 3.20 | 1.22 | 1.83 |
- 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 20 ft span, a W12×106 carries a factored load of 12.3 kips per foot (LRFD) or an allowable load of 8.18 kips per foot (ASD). A live load of 5.01 kips per foot would deflect it span/360, which is 0.67 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.
W12×106 questions
What does W12×106 mean?
W means a wide flange shape. 12 is its nominal depth in inches (the actual depth is 12.9 in) and 106 is its weight in pounds per foot.
How much does a W12×106 weigh?
106 pounds per foot, so a 20 ft W12×106 weighs about 2,120 pounds.
How far can a W12×106 span?
It depends on the load. Braced along its length, it carries 78.7 kips per foot of factored load at 6 ft and 4.80 kips per foot at 32 ft; the load table has the spans in between. Floor beams are often 19 to 26 ft for this depth (span-to-depth ratios of about 18 to 24), where deflection usually governs.
Is a W12×106 a compact section?
Yes. Its flanges (bf/2tf = 6.17) and web (h/tw = 15.9) are both compact for bending in 50 ksi steel.