Cold-formed steel fastener connection

A group of screws, bolts or welds joining two cold-formed sheets under shear and tension, to Chapter J of the AISI S100-16 North American Specification with Supplement S2-20, with ASCE 7-22 load combinations. You enter the forces on the group; they are shared equally among the fasteners.

Inputs of the cold-formed steel connection #

• Fastener: screws (No. 6 to 1/4 in.), bolts (1/4 to 3/4 in., ASTM A307, F3125 A325 and A490, A354 BD, A449), a fillet weld or a flare groove weld.
• Screw strengths Pss and Pts: the manufacturer's or tested values. At 0 the module uses the CFSEI F701-12 values printed in the SSMA Guide (2022). The specification asks you for these, so please use your product's.
• Penetration tc: the lesser of the depth of penetration and t2 (J4). 0 uses t2.
• Washer and nonuniform pull-over: a washer sets the pull-over diameter (J4.4.2). Tick nonuniform for an eccentric load that takes 50 % of the pull-over strength (J4.5.1).
• Bolts: threads in or out of the shear plane, single or double shear, hole type and washers set the factor mf (Table J3.3.1-2). Tick hole deformation when it is a design consideration (J3.3.2).
• Welds: total length, the load along or across the weld. The weld leg, the electrode and the flare throat matter above 0.10 in. Enter the throat your procedure qualifies.
• Pattern: the number of fasteners, how many lie across the load, the spacings, and the end and edge distances.
• Sheets: thickness by mils (SSMA design thickness) or custom, Fy and Fu of each. The sheet at the head is t1, the sheet at the tip is t2.
• Rupture: on by default (J6). A sheet width turns on tension rupture of a flat sheet or strap. Other shapes need their own net section.
• Forces: nominal shear and tension on the whole group by load type. Eccentricity is yours to add.

Auto-design varies the number of fasteners in whole rows and their size, or the weld length. Sheets, forces and the fastener kind are kept.

Checks performed #

Limitations #

• Forces are shared equally. Eccentric groups and prying are not analysed.
• Screws, bolts and anchors into wood, concrete or masonry are not covered: S100 J7 sends them to product data, and S240 B1.5.6 to the other material's code.
• Power-actuated fasteners, arc spot, arc seam and top arc seam welds are not built.
• Tension rupture covers a flat sheet only. Shear lag in an angle or channel is not computed.
• The two combined equations for pull-over and pull-out have narrow limits. Outside them the module says so and does not apply them.
• A thinnest part over 3/16 in. is not feasible here: Chapter J sends it to AISC 360.
• Pull-over at a bolt head has no equation in the specification. It is a note.

Verification examples #

Verification status: 68 values compared in 30 examples (28 published, 2 hand calculations from the cited equations): 68 within tolerance, 0 recorded deviations. Code basis: the provisions it uses were read in the target edition.

No free source on disk prints a worked connection example. The AISI Cold-Formed Steel Design Manual would have them; it is on the list of documents to buy.

• Published table values: SSMA Product Technical Guide (2022) p. 70, 18 screw rows of shear, pull-out and pull-over and 10 weld rows, are read back through the module. All are within 2 % or 5 lb, the rounding of a table. The table prints the 2016 equations under their older section numbers (E4 for J4), and uses the longer-weld equations J2.5-3 and -4 for its longitudinal fillet column.
• Hand calculations, from the cited equations: bolt bearing, bolt shear, shear rupture, the screw case with t2 well over t1, the interpolation, the bearing factor table, F'nt and the fillet ranges. No published value checks these.