S18×70 standard beam

Detailing dimensions and section properties from the AISC Shapes Database, 16th Edition. Values are shown to the nearest 1/16 in. as they appear on a shop drawing.

S18×70 measures 18 in. deep with a 6 1/4 in. flange, on a 11/16 in. web and 11/16 in. flanges.

At 70 lb per foot it is the heaviest of the 2 S18 sizes, which run from 54.7 to 70 lb/ft.

For strong-axis bending its section modulus is Sx = 103 in³ and its moment of inertia Ix = 923 in⁴, with a plastic modulus Zx = 124 in³.

Detailing dimensions

Depth (d)18"
Flange width (bf)6 1/4"
Web thickness (tw)11/16"
Flange thickness (tf)11/16"
k (detailing)1 1/2"
Workable gage (g)3 1/2"

Section properties

Weight70 lb/ft
Area (A)20.5 in²
Ix923 in⁴
Sx103 in³
Zx124 in³
rx6.7 in
Iy24 in⁴
Sy7.69 in³
Zy14.3 in³
ry1.08 in
J4.1 in⁴

Other S18 sizes

Same nominal size, different weight — useful when you are checking a substitution or a lighter section.

S18×54.7

Similar weight standard beams

Comparable 70 lb/ft sections in other standard beam sizes.

S20×6666 lb/ft · Sx 119 in³S20×7575 lb/ft · Sx 128 in³S24×8080 lb/ft · Sx 175 in³S20×8686 lb/ft · Sx 155 in³S15×5050 lb/ft · Sx 64.7 in³S12×5050 lb/ft · Sx 50.6 in³S24×9090 lb/ft · Sx 187 in³S20×9696 lb/ft · Sx 165 in³

Detailing values are rounded to the nearest 1/16 in. per the AISC Steel Construction Manual. Verify critical dimensions against the current Manual before fabrication. Need S18×70 cut, formed, or fabricated? Huntington Steel & Supply Co.

Browse more: Standard beams · Steel Beam Size Chart

Interactive drawing