W12×305 Steel Beam
A W12×305 is a wide flange steel beam 16.3 inches deep with 13.2-inch flanges, weighing 305 pounds per foot. In ASTM A992 steel (Fy = 50 ksi) it has a design bending strength of 2,014 kip-ft (LRFD) when its compression flange is braced, and a design shear strength of 797 kips.
Design a W12×305 beam Opens a 24 ft span in the free beam designer.
W12×305 dimensions
| Dimension | Value |
|---|---|
| Depth, d | 16.3 in |
| Flange width, bf | 13.2 in |
| Flange thickness, tf | 2.71 in |
| Web thickness, tw | 1.63 in |
| Distance to web toe of fillet, kdes | 3.30 in |
| Distance between flange centroids, ho | 13.59 in |
| Cross-sectional area, A | 89.6 in2 |
| Weight | 305 lb/ft |
Dimensions are AISC design values. Detailing dimensions are rounded to the nearest 1/16 in.
W12×305 section properties
| Property | Strong axis (x) | Weak axis (y) |
|---|---|---|
| Moment of inertia, I | 3550 in4 | 1050 in4 |
| Elastic section modulus, S | 435 in3 | 159 in3 |
| Plastic section modulus, Z | 537 in3 | 244 in3 |
| Radius of gyration, r | 6.29 in | 3.42 in |
| Torsion and slenderness | Value |
|---|---|
| Torsional constant, J | 185 in4 |
| Warping constant, Cw | 48600 in6 |
| Effective radius of gyration, rts | 4.05 in |
| Flange slenderness, bf/2tf | 2.45 |
| Web slenderness, h/tw | 5.98 |
W12×305 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 = 2,014 kip-ft | Mn/Ω = 1,340 kip-ft |
| Shear | φVn = 797 kips | Vn/Ω = 531 kips |
If the compression flange isn't braced, the beam can buckle sideways before it yields. Up to Lp = 12.1 ft between braces it keeps its full strength; past Lr = 136.7 ft it buckles elastically. With uniform moment between braces (Cb = 1.0):
| Unbraced length, Lb | φMn (LRFD) | Mn/Ω (ASD) |
|---|---|---|
| Braced | 2,014 kip-ft | 1,340 kip-ft |
| 10 ft | 2,014 kip-ft | 1,340 kip-ft |
| 12.1 ft (Lp) | 2,014 kip-ft | 1,340 kip-ft |
| 20 ft | 1,958 kip-ft | 1,303 kip-ft |
| 30 ft | 1,888 kip-ft | 1,256 kip-ft |
| 40 ft | 1,818 kip-ft | 1,210 kip-ft |
| 50 ft | 1,748 kip-ft | 1,163 kip-ft |
| 60 ft | 1,678 kip-ft | 1,117 kip-ft |
| 70 ft | 1,608 kip-ft | 1,070 kip-ft |
| 80 ft | 1,538 kip-ft | 1,024 kip-ft |
| 90 ft | 1,468 kip-ft | 977 kip-ft |
| 100 ft | 1,399 kip-ft | 930 kip-ft |
| 110 ft | 1,329 kip-ft | 884 kip-ft |
| 136.7 ft (Lr) | 1,142 kip-ft | 760 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.
W12×305 load table by span
The largest uniform load a simply supported W12×305 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 0.305 kips per foot.
| Span | Factored load (LRFD) | Allowable load (ASD) | Load at span/360 | Load at span/240 |
|---|---|---|---|---|
| 8 ft | 199.3* | 132.8* | 297.9 | 446.8 |
| 10 ft | 159.4* | 106.3* | 152.5 | 228.8 |
| 12 ft | 111.9 | 74.4 | 88.3 | 132.4 |
| 14 ft | 82.2 | 54.7 | 55.6 | 83.4 |
| 16 ft | 62.9 | 41.9 | 37.2 | 55.9 |
| 18 ft | 49.7 | 33.1 | 26.2 | 39.2 |
| 20 ft | 40.3 | 26.8 | 19.1 | 28.6 |
| 22 ft | 33.3 | 22.1 | 14.3 | 21.5 |
| 24 ft | 28.0 | 18.6 | 11.0 | 16.5 |
| 26 ft | 23.8 | 15.9 | 8.68 | 13.0 |
| 28 ft | 20.5 | 13.7 | 6.95 | 10.4 |
| 30 ft | 17.9 | 11.9 | 5.65 | 8.47 |
| 32 ft | 15.7 | 10.5 | 4.65 | 6.98 |
| 34 ft | 13.9 | 9.27 | 3.88 | 5.82 |
| 36 ft | 12.4 | 8.27 | 3.27 | 4.90 |
| 38 ft | 11.2 | 7.42 | 2.78 | 4.17 |
| 40 ft | 10.1 | 6.70 | 2.38 | 3.57 |
- 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 24 ft span, a W12×305 carries a factored load of 28.0 kips per foot (LRFD) or an allowable load of 18.6 kips per foot (ASD). A live load of 11.0 kips per foot would deflect it span/360, which is 0.80 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.
W12×305 questions
What does W12×305 mean?
W means a wide flange shape. 12 is its nominal depth in inches (the actual depth is 16.3 in) and 305 is its weight in pounds per foot.
How much does a W12×305 weigh?
305 pounds per foot, so a 20 ft W12×305 weighs about 6,100 pounds.
How far can a W12×305 span?
It depends on the load. Braced along its length, it carries 199.3 kips per foot of factored load at 8 ft and 10.1 kips per foot at 40 ft; the load table has the spans in between. Floor beams are often 24 to 33 ft for this depth (span-to-depth ratios of about 18 to 24), where deflection usually governs.
Is a W12×305 a compact section?
Yes. Its flanges (bf/2tf = 2.45) and web (h/tw = 5.98) are both compact for bending in 50 ksi steel.