Sheathing-braced cold-formed steel stud
A wall stud braced by its sheathing, on both faces or on one face with discrete bracing of the other flange, under axial load and wind. The sheathing braced strength of AISI S240-20 B1.2.2 and B3.2, the stud without the sheathing (Eq. B1.2.2-1), the sheathing connections checked as braces (AISI S100-16 C2.3), and the all-steel alternative with bridging shown beside it.
The cold-formed steel stud type offers sheathing braced design with identical sheathing on both faces. This type adds one face with discrete braces, the brace demand on the sheathing connections, and the side-by-side comparison with all steel design.
Inputs of the sheathing-braced stud #
- Stud and loads: an SSMA designation or custom dimensions, Fy, the height, the spacing (at most 24 in., S240 B1.2.2.1(b)), the axial load per stud by load type, and the wind pressure (both directions).
- Sheathing: both faces or one face; gypsum with its screws (the four rows of S240 Table B3.2-1) or other structural sheathing with your nominal stud load limit; the connector spacing (gypsum screws at most 12 in.); the sheathing's rotational restraint kφ (S240 Appendix 1, your entry, 0 if unknown).
- One face sheathed: the brace spacing of the unsheathed flange (S240 B1.2.2.3: at most 8 ft for curtain wall studs) and Ly = Lt for compression. S240 B3.2.1(b) gives twice the connector spacing for two faces; with one face the braces set it, your value.
- Connections as braces: the connector's lateral strength (available, for the method) and stiffness, from tests or a report. Left at 0, the demand is reported, not checked.
- All-steel alternative: the bridging spacing, also used for the stud without the sheathing.
Auto-design varies the SSMA stud (lightest first) and the sheathing connector spacing (widest first). Height, spacing, loads, sheathing and braces are kept.
Checks performed #
| Check | Basis |
|---|---|
| Studs at most 24 in. on center; gypsum screws at most 12 in. | S240 B1.2.2.1(b), B3.2.1(b) |
| Compression: Lx the height, Ly = Lt twice the connector spacing (two faces), K = 1; distortional with kφ | S240 B3.2.1(b); S100 E2, E3, E4 |
| Flexure: F3 with Fn = Fy and F4 with kφ; with one face, F2 over the brace spacing for the other direction | S240 B3.2.2(b); S100 F2, F3, F4 |
| Axial load and bending with B1 | S100 H1.2, C1.2.1.1 |
| Nominal stud load against the gypsum connection limit | S240 Table B3.2-1 (or your limit) |
| The stud without the sheathing, 1.2D + (0.5L or 0.2S) + 0.2W | S240 B1.2.2.4, Eq. B1.2.2-1 (LRFD factors) |
| Sheathing connections as braces: strength 0.01 Pra and stiffness | S100 C2.3, Eqs. C2.3-1, C2.3-2 (a rational check) |
| All-steel alternative with bridging | S240 B1.2.2.1(a) (advisory, not counted) |
Limitations #
- The C2.3 brace check is a rational check (S240 does not require it for sheathing braced design); the connector values are yours. It takes the axial load only.
- With one face sheathed, Ly = Lt is your entry: S240 states the two-face rule only (to confirm against the code text).
- Distortional buckling is taken without discrete restraint (Lm = Lcrd) unless kφ is entered.
- Tracks, bridging connections and the sheathing's own span and shear are not designed here.
Verification examples #
Verification status: 8 values compared in 2 examples (2 published, 0 hand calculations from the cited equations): 8 within tolerance, 0 recorded deviations. Thin: only 2 published examples. Code basis: not yet recorded for this module.
The Table B3.2-1 limits are the values printed in AISI S240-20. No published worked example of a sheathing-braced stud is in the free library; the brace demand and statics are hand calculations of S100 Eqs. C2.3-1 and C2.3-2.