Cold-formed steel parapet
A C-stud that rises from its base at the roof past a kicker brace to a free top: the parapet wind on it, the stud, the kicker down to the roof framing and the screws at the kicker's ends. To AISI S100-16 (with S2-20), with the parapet wind of ASCE 7-22 30.6.
Inputs of the parapet stud #
- Stud: an SSMA designation or custom dimensions, Fy and Fu, the spacing and the height above its base support.
- Flange bracing: sheathing on both flanges (bending at Fn = Fy) or discrete braces at a spacing (lateral-torsional buckling with Cb = 1.0). Which applies is your call.
- Weak-axis and torsional length for compression: the bridging or sheathing fastener spacing you rely on (S240 B1.2.2).
- Kicker: its height on the stud, its run to the roof framing (the angle follows), an SSMA designation, Fy and the effective length factor K (1.0 for pinned ends, prefilled), the screws and their count at each end, and the roof framing's thickness and Fu.
- Wind from ASCE 7-22 30.6: V, exposure, Kzt, Kd (0.85 prefilled), the ground elevation for Ke (0 takes Ke = 1.0), the height of the parapet's top, and the location: interior (wall zone 4 with roof edge zone 2) or corner (wall zone 5 with roof corner zone 3). The roof must slope 7° or less (Fig. 30.3-2A). The Fig. 30.3-2A note 5 option applies the parapet note to the roof face; it is off by default, which takes the roof value as printed.
- Or the net pressures entered: toward the roof and away from it, at the strength level.
- Deflection: the wind factor (0.42, S240 B1.1.2 and the IBC Table 1604.3 footnote) and the limits: the tip on twice the cantilever, the back span on its span.
Auto-design varies the stud and the kicker (SSMA designations, lightest first) and the screws at each end of the kicker. Heights, the kicker's position, the wind and the limits are kept; Fy when unlocked.
Checks performed #
| Check | Basis |
|---|---|
| Parapet wind, load cases A and B | ASCE 7-22 30.6, Eq. 30.6-1, Figs. 30.3-1, 30.3-2A, 26.10 |
| Stud flexure | S100 F2, F3 |
| Stud shear | S100 G2 |
| Stud bending and shear | S100 H2 |
| Stud compression below the kicker (case B) and compression with bending | S100 E2, E3, H1.2 with B1 (C1.2.1.1) |
| Stud tension with bending (case A) | S100 D2, H1.1 |
| Kicker compression and tension | S100 E2, E3, D2 |
| Kicker screws at each end: sheet shear, screw shear | S100 J4.3.1, J4.3.2 |
| Tip and back span deflection | IBC Table 1604.3 (limits entered), S100 L1 |
The stud carries both faces of the parapet, so the internal pressure acts on both and cancels: the stud's net pressure is qp Kd times the difference of the two faces' (GCp). Wind is analysed alone (1.0W for LRFD, 0.6W for ASD); the stud's weight is vertical and not counted in bending.
Limitations #
- Buildings with h up to 60 ft and roofs up to 7°, for the computed pressures. Otherwise enter the net pressures.
- One kicker per stud, pinned at both ends, landing at the level of the stud's base.
- The base track and its anchorage (the base reaction is reported), the roof framing at the kicker's lower end, bridging, the cap and the finish are not designed.
- Web crippling of the stud at the kicker and at the base is not checked: the kicker is screwed to the web, and the base detail is yours.
Verification examples #
Verification status: 6 values compared in 2 examples (0 published, 2 hand calculations from the cited equations): 6 within tolerance, 0 recorded deviations. No published example: every value is a hand calculation. That checks the program against this reading of the code, not the reading itself. Code basis: not yet recorded for this module.
No published worked example of a parapet stud with a kicker is in the free library. The values are hand calculations: one ASCE 7-22 30.6 pressure case worked from the equations and figures, and the statics of the stud and kicker under entered pressures. A CFSEI Technical Note or AISI D110 example would replace them.