Cold-formed steel bypass and infill framing
Exterior wind studs that pass the slab edges on slide clips (bypass), or studs set between the slabs with a deflection track or slide clips at the head (infill). The stud over its spans, the clips' loads, screws and travel, and the infill head. To AISI S100-16 and AISI S240-20 B3.2.5, with the loads combined by ASCE 7-22 2.3.1 or 2.4.1.
The curtain wall type covers single and double span wind studs with a deflection track; this type adds multi-span bypass studs on slide clips, the clip reactions and screws, the clip's travel against the slab movement, and the infill head on slide clips.
Inputs of the bypass framing #
- Studs: bypass or infill; an SSMA designation or custom dimensions, Fy, Fu, the spacing, the floor-to-floor height (bypass, 2 to 4 equal spans between clips, a cantilever above the top clip) or the clear height (infill), and the bridging spacing.
- Loads: the wind pressure, both directions (your ASCE 7-22 Chapter 30 value), and the cladding's dead load carried down the stud to its base (0 when the slabs carry it).
- Limits: the wind factor for deflection (0.42, IBC Table 1604.3 footnote), the span limit (L/600 behind brick veneer, L/360 plaster, L/240 other brittle finishes: your choice) and the cantilever limit.
- Slide clips: the clip's available strength from its manufacturer (for the stud and the anchorage to the slab), its thickness and Fu, the screws stud to clip, the clip's travel each way, and the slab edge's movement and your tolerance.
- Infill head: a deflection track (thickness, Fy, flange, slip gap) or slide clips.
Auto-design varies the SSMA stud (lightest first) and the screws per clip. Heights, spacing, wind, clips, head detail and limits are kept.
Checks performed #
| Check | Basis |
|---|---|
| Flexure, bridging spacing for F2 and F4 | S100 F2, F3, F4 |
| Shear | S100 G2 |
| Bending and shear at a clip | S100 H2, Eq. H2-1 |
| Compression from the cladding weight, with bending and B1 | S100 E2, E3, H1.2, C1.2.1.1 |
| Deflection in a span and at the top of a cantilever | IBC Table 1604.3 (your limits) |
| Slide clip reaction | Manufacturer's report (entered) |
| Screws stud to clip | S100 J4.3.1, J4.3.2 |
| Clip travel at least the movement plus the tolerance | Manufacturer's travel, your movement |
| Infill deflection track: stud web crippling, track flange, range, gap | S240 B3.2.5.2, Eqs. B3.2.5.2-1, -2, Table B3.2.5.2-1; S100 G5 |
Limitations #
- Equal spans between clips; the base is a pinned support (a track), designed in the track and anchorage types.
- The clip's anchorage to the slab edge is inside the clip strength you enter. The slab edge movement is your value.
- The compression from the cladding is taken at the base with the largest wind moment anywhere on the stud (conservative).
- Deflection uses the gross moment of inertia.
Verification examples #
Verification status: 11 values compared in 2 examples (0 published, 2 hand calculations from the cited equations): 11 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 bypass or infill framing is in the free library. The values are hand calculations of two-span continuous beam formulas, S100 J4.3.1, S240 Eqs. B3.2.5.2-1, -2 and S100 G5.