W16×100 Steel Beam
A W16×100 is a wide flange steel beam 17 inches deep with 10.4-inch flanges, weighing 100 pounds per foot. In ASTM A992 steel (Fy = 50 ksi) it has a design bending strength of 743 kip-ft (LRFD) when its compression flange is braced, and a design shear strength of 298 kips.
Design a W16×100 beam Opens a 27 ft span in the free beam designer.
W16×100 dimensions
| Dimension | Value |
|---|---|
| Depth, d | 17.0 in |
| Flange width, bf | 10.4 in |
| Flange thickness, tf | 0.985 in |
| Web thickness, tw | 0.585 in |
| Distance to web toe of fillet, kdes | 1.39 in |
| Distance between flange centroids, ho | 16.02 in |
| Cross-sectional area, A | 29.5 in2 |
| Weight | 100 lb/ft |
Dimensions are AISC design values. Detailing dimensions are rounded to the nearest 1/16 in.
W16×100 section properties
| Property | Strong axis (x) | Weak axis (y) |
|---|---|---|
| Moment of inertia, I | 1490 in4 | 186 in4 |
| Elastic section modulus, S | 175 in3 | 35.7 in3 |
| Plastic section modulus, Z | 198 in3 | 54.9 in3 |
| Radius of gyration, r | 7.10 in | 2.51 in |
| Torsion and slenderness | Value |
|---|---|
| Torsional constant, J | 7.73 in4 |
| Warping constant, Cw | 11900 in6 |
| Effective radius of gyration, rts | 2.92 in |
| Flange slenderness, bf/2tf | 5.29 |
| Web slenderness, h/tw | 24.3 |
W16×100 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 = 743 kip-ft | Mn/Ω = 494 kip-ft |
| Shear | φVn = 298 kips | Vn/Ω = 199 kips |
If the compression flange isn't braced, the beam can buckle sideways before it yields. Up to Lp = 8.9 ft between braces it keeps its full strength; past Lr = 32.7 ft it buckles elastically. With uniform moment between braces (Cb = 1.0):
| Unbraced length, Lb | φMn (LRFD) | Mn/Ω (ASD) |
|---|---|---|
| Braced | 743 kip-ft | 494 kip-ft |
| 8.9 ft (Lp) | 742 kip-ft | 494 kip-ft |
| 10 ft | 729 kip-ft | 485 kip-ft |
| 20 ft | 610 kip-ft | 406 kip-ft |
| 30 ft | 491 kip-ft | 327 kip-ft |
| 32.7 ft (Lr) | 459 kip-ft | 306 kip-ft |
| 40 ft | 362 kip-ft | 241 kip-ft |
| 50 ft | 282 kip-ft | 188 kip-ft |
| 60 ft | 231 kip-ft | 154 kip-ft |
| 70 ft | 197 kip-ft | 131 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.
W16×100 load table by span
The largest uniform load a simply supported W16×100 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 0.100 kips per foot.
| Span | Factored load (LRFD) | Allowable load (ASD) | Load at span/360 | Load at span/240 |
|---|---|---|---|---|
| 9 ft | 66.3* | 44.2* | 87.8 | 131.7 |
| 11 ft | 49.1 | 32.7 | 48.1 | 72.1 |
| 13 ft | 35.1 | 23.4 | 29.1 | 43.7 |
| 15 ft | 26.4 | 17.6 | 19.0 | 28.5 |
| 17 ft | 20.6 | 13.7 | 13.0 | 19.5 |
| 19 ft | 16.5 | 10.9 | 9.33 | 14.0 |
| 21 ft | 13.5 | 8.96 | 6.91 | 10.4 |
| 23 ft | 11.2 | 7.47 | 5.26 | 7.89 |
| 25 ft | 9.50 | 6.32 | 4.10 | 6.15 |
| 27 ft | 8.15 | 5.42 | 3.25 | 4.88 |
| 29 ft | 7.06 | 4.70 | 2.62 | 3.94 |
| 31 ft | 6.18 | 4.11 | 2.15 | 3.22 |
| 33 ft | 5.45 | 3.63 | 1.78 | 2.67 |
| 35 ft | 4.85 | 3.23 | 1.49 | 2.24 |
| 37 ft | 4.34 | 2.89 | 1.26 | 1.90 |
| 39 ft | 3.91 | 2.60 | 1.08 | 1.62 |
| 41 ft | 3.53 | 2.35 | 0.93 | 1.39 |
| 43 ft | 3.21 | 2.14 | 0.81 | 1.21 |
- 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 27 ft span, a W16×100 carries a factored load of 8.15 kips per foot (LRFD) or an allowable load of 5.42 kips per foot (ASD). A live load of 3.25 kips per foot would deflect it span/360, which is 0.90 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.
W16×100 questions
What does W16×100 mean?
W means a wide flange shape. 16 is its nominal depth in inches (the actual depth is 17.0 in) and 100 is its weight in pounds per foot.
How much does a W16×100 weigh?
100 pounds per foot, so a 20 ft W16×100 weighs about 2,000 pounds.
How far can a W16×100 span?
It depends on the load. Braced along its length, it carries 66.3 kips per foot of factored load at 9 ft and 3.21 kips per foot at 43 ft; the load table has the spans in between. Floor beams are often 26 to 34 ft for this depth (span-to-depth ratios of about 18 to 24), where deflection usually governs.
Is a W16×100 a compact section?
Yes. Its flanges (bf/2tf = 5.29) and web (h/tw = 24.3) are both compact for bending in 50 ksi steel.