W12×136 Steel Beam
A W12×136 is a wide flange steel beam 13.4 inches deep with 12.4-inch flanges, weighing 136 pounds per foot. In ASTM A992 steel (Fy = 50 ksi) it has a design bending strength of 803 kip-ft (LRFD) when its compression flange is braced, and a design shear strength of 318 kips.
Design a W12×136 beam Opens a 21 ft span in the free beam designer.
W12×136 dimensions
| Dimension | Value |
|---|---|
| Depth, d | 13.4 in |
| Flange width, bf | 12.4 in |
| Flange thickness, tf | 1.25 in |
| Web thickness, tw | 0.790 in |
| Distance to web toe of fillet, kdes | 1.85 in |
| Distance between flange centroids, ho | 12.15 in |
| Cross-sectional area, A | 39.9 in2 |
| Weight | 136 lb/ft |
Dimensions are AISC design values. Detailing dimensions are rounded to the nearest 1/16 in.
W12×136 section properties
| Property | Strong axis (x) | Weak axis (y) |
|---|---|---|
| Moment of inertia, I | 1240 in4 | 398 in4 |
| Elastic section modulus, S | 186 in3 | 64.2 in3 |
| Plastic section modulus, Z | 214 in3 | 98.0 in3 |
| Radius of gyration, r | 5.58 in | 3.16 in |
| Torsion and slenderness | Value |
|---|---|
| Torsional constant, J | 18.5 in4 |
| Warping constant, Cw | 14700 in6 |
| Effective radius of gyration, rts | 3.61 in |
| Flange slenderness, bf/2tf | 4.96 |
| Web slenderness, h/tw | 12.3 |
W12×136 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 = 803 kip-ft | Mn/Ω = 534 kip-ft |
| Shear | φVn = 318 kips | Vn/Ω = 212 kips |
If the compression flange isn't braced, the beam can buckle sideways before it yields. Up to Lp = 11.2 ft between braces it keeps its full strength; past Lr = 63.2 ft it buckles elastically. With uniform moment between braces (Cb = 1.0):
| Unbraced length, Lb | φMn (LRFD) | Mn/Ω (ASD) |
|---|---|---|
| Braced | 803 kip-ft | 534 kip-ft |
| 10 ft | 803 kip-ft | 534 kip-ft |
| 11.2 ft (Lp) | 803 kip-ft | 534 kip-ft |
| 20 ft | 749 kip-ft | 498 kip-ft |
| 30 ft | 689 kip-ft | 458 kip-ft |
| 40 ft | 628 kip-ft | 418 kip-ft |
| 50 ft | 568 kip-ft | 378 kip-ft |
| 60 ft | 508 kip-ft | 338 kip-ft |
| 63.2 ft (Lr) | 488 kip-ft | 325 kip-ft |
| 70 ft | 439 kip-ft | 292 kip-ft |
| 80 ft | 383 kip-ft | 255 kip-ft |
| 90 ft | 340 kip-ft | 226 kip-ft |
| 100 ft | 305 kip-ft | 203 kip-ft |
| 110 ft | 277 kip-ft | 184 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.
W12×136 load table by span
The largest uniform load a simply supported W12×136 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 0.136 kips per foot.
| Span | Factored load (LRFD) | Allowable load (ASD) | Load at span/360 | Load at span/240 |
|---|---|---|---|---|
| 7 ft | 90.7* | 60.5* | 155.3 | 233.0 |
| 9 ft | 70.6* | 47.0* | 73.1 | 109.6 |
| 11 ft | 53.1 | 35.3 | 40.0 | 60.0 |
| 13 ft | 38.0 | 25.3 | 24.2 | 36.4 |
| 15 ft | 28.5 | 19.0 | 15.8 | 23.7 |
| 17 ft | 22.2 | 14.8 | 10.8 | 16.3 |
| 19 ft | 17.8 | 11.8 | 7.77 | 11.7 |
| 21 ft | 14.6 | 9.69 | 5.75 | 8.63 |
| 23 ft | 12.1 | 8.07 | 4.38 | 6.57 |
| 25 ft | 10.3 | 6.83 | 3.41 | 5.11 |
| 27 ft | 8.81 | 5.86 | 2.71 | 4.06 |
| 29 ft | 7.63 | 5.08 | 2.18 | 3.28 |
| 31 ft | 6.68 | 4.44 | 1.79 | 2.68 |
| 33 ft | 5.90 | 3.92 | 1.48 | 2.22 |
- 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 21 ft span, a W12×136 carries a factored load of 14.6 kips per foot (LRFD) or an allowable load of 9.69 kips per foot (ASD). A live load of 5.75 kips per foot would deflect it span/360, which is 0.70 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.
W12×136 questions
What does W12×136 mean?
W means a wide flange shape. 12 is its nominal depth in inches (the actual depth is 13.4 in) and 136 is its weight in pounds per foot.
How much does a W12×136 weigh?
136 pounds per foot, so a 20 ft W12×136 weighs about 2,720 pounds.
How far can a W12×136 span?
It depends on the load. Braced along its length, it carries 90.7 kips per foot of factored load at 7 ft and 5.90 kips per foot at 33 ft; the load table has the spans in between. Floor beams are often 20 to 27 ft for this depth (span-to-depth ratios of about 18 to 24), where deflection usually governs.
Is a W12×136 a compact section?
Yes. Its flanges (bf/2tf = 4.96) and web (h/tw = 12.3) are both compact for bending in 50 ksi steel.