Common context
Common project roles include truss components, lintels, specialty framing, reinforcement, and connections where the ST proportions are specifically useful.
AISC v16.0 · ST shape
ST12X40
ST12X40 weighs 40 lb/ft, has a depth of 12 in, a cross-sectional area of 11.7 in², and an x-axis elastic section modulus Sx of 18.6 in³. Open the full US customary property record or generate 2D, data, report, and 3D reference files locally in your browser.
Nominal profile
Units · inches
Building nominal profile…
- Weight
- 40 lb/ft
- Area
- 11.7 in²
- Depth
- 12 in
- Elastic Sx
- 18.6 in³
From designation to geometry
Reading the ST12X40 record
The ST designation identifies a tee depth series and nominal weight per foot. Use its own tabulated depth d = 12 in and flange width bf = 7 in rather than halving every dimension of another member.
This tee has web or stem thickness tw = 0.5 in, flange thickness tf = 0.87 in and centroid distance y = 3.3 in. Stem and flange orientation matter when matching the table's axes to a model.
Ix = 162 in⁴ and Iy = 21 in⁴ refer to the database x- and y-axes. Here Ix is numerically larger. Axis letters are labels, not a guarantee that x is always the larger axis. These are geometric properties, not allowable loads or complete member capacities.
Match the axis and dimension conventions to the figures in the AISC v16.0 workbook Readme. The profile above simplifies manufacturing geometry; its outline is not used to recalculate the published properties.
Worked quantity example
Nominal weight for ST12X40
Assume 3 pieces, each 20 ft (6.096 m) long. This is a hypothetical quantity example, not a stock-length or lifting recommendation.
| Quantity | Calculation | Nominal pounds | Kilogram equivalent |
|---|---|---|---|
| One 20 ft piece | 20 ft × 40 lb/ft | 800 lb | 362.874 kg |
| 3 pieces | 3 × 800 lb | 2,400 lb | 1,088.622 kg |
Conversion: 1 lb = 0.45359237 kg; displayed results are rounded. This multiplication excludes connection plates, bolts, weld metal, coatings, cutting allowances and actual material variation. Use the material takeoff for your own lengths and quantities.
Shape family context
What is a structural tee cut from an S-shape?
An ST is a structural tee produced from an American Standard S-shape. Its flange geometry and proportions differ from WT and MT series tees.
Learn how shape properties workDetailing watch
Check tapered flange effects, stem orientation, connection surface, availability, and exact section properties before replacing or pairing it with another tee series.
Portable reference files
Download ST12X40 your way.
Every file is generated locally in your browser from the same nominal profile and AISC v16.0 reference record.
CAD, vector, and image
Use the profile in CAD, illustration, plotting, reports, or presentations.
Tables and portable data
Take a printable datasheet, spreadsheet, structured record, or plain-text table.
Extrude a nominal member
Enter a member length in inches. Mesh files are generated from the nominal reference profile.
One-click package
Complete 2D + data bundle
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Dimensions & properties
ST12X40 reference data.
Values below are derived from the AISC Shapes Database v16.0 in US customary units. A dash indicates that a property is not applicable or not included for this family.
Nominal dimensions
- W Nominal weight
- 40 lb/ft
- A Area
- 11.7 in²
- d Depth / angle leg dimension d
- 12 in
- ddet Detailing depth
- 12 in
- bf Flange width
- 7 in
- bfdet Detailing flange width
- 7 in
- tw Web thickness
- 0.5 in
- twdet Detailing web thickness
- 0.5 in
- tf Flange thickness
- 0.87 in
- tfdet Detailing flange thickness
- 0.875 in
- kdes Design k distance
- 1.75 in
- kdet Detailing k distance
- 1.75 in
Centroid & detailing
- y Centroid y
- 3.3 in
- yp Plastic neutral axis y
- 0.909 in
- WGi Workable gage, inner
- 4 in
X-axis properties
- Ix X-axis moment of inertia
- 162 in⁴
- Zx X-axis plastic section modulus
- 33.6 in³
- Sx X-axis elastic section modulus
- 18.6 in³
- rx X-axis radius of gyration
- 3.72 in
Y- and z-axis properties
- Iy Y-axis moment of inertia
- 21 in⁴
- Zy Y-axis plastic section modulus
- 10.4 in³
- Sy Y-axis elastic section modulus
- 6 in³
- ry Y-axis radius of gyration
- 1.34 in
Torsion, warping & perimeters
- J Torsional constant
- 2.44 in⁴
- Cw Warping constant
- 6.94 in⁶
Compare published reference values
ST12X40 alongside nearby ST records
These records share the same nominal series, outside envelope or leg arrangement, depending on the family. Peers are ordered by absolute weight difference, then listed depth and designation. The table does not rank structural performance or approve a substitution.
| Record | Weight (lb/ft) | Depth (in) | Area (in²) | Ix (in⁴) | Iy (in⁴) |
|---|---|---|---|---|---|
| ST12X40 (this record) | 40 | 12 | 11.7 | 162 | 21 |
| ST12X45 | 45 | 12 | 13.2 | 190 | 22.3 |
| ST12X50 | 50 | 12 | 14.7 | 215 | 23.7 |
Relative to ST12X40, ST12X45 changes nominal weight by +5 lb/ft, listed depth by 0 in, and area by +1.5 in². At the same hypothetical 20 ft length, the nominal weight difference is +100 lb.
Open these records in the full comparison tool
Compare the remaining dimensions, axis conventions, grade, availability and project requirements separately. Weight or section-property similarity does not establish matching connection geometry or member capacity.
Data is derived from the AISC Shapes Database v16.0, consistent with the AISC Steel Construction Manual, 16th Edition, 1st Printing. AISC advises professional verification before use in a specific application. The downloadable DXF is a nominal reference profile and may simplify rolled fillets, flange tapers, angle radii, HSS corner radii, and other manufacturing geometry. Verify all dimensions and suitability before design, detailing, ordering, or fabrication.
From reference to deliverable