CFS Screw Connection Calculator, AISI S100-16 w/S3-22

What it checks

The module designs cold-formed steel screw connections, evaluating the fastener's capacity against applied shear and tension demands. It operates under the Load and Resistance Factor Design (LRFD) method with a resistance factor of 0.50, or the Allowable Strength Design (ASD) method with a safety factor of 3.00. The sequence of checks begins with shear capacity, which is determined by the combined effects of tilting and bearing. The module then assesses tension capacity, considering both pullout and pullover failure modes. Finally, it verifies that the connection geometry satisfies the required end and edge distance limits to ensure the calculated capacities are valid.

Inputs

Design Method - Selection of LRFD or ASD, which determines the applicable capacity factor (φ = 0.50 or Ω = 3.00).
Shear Demand - The factored or service shear force applied to the screw connection (kips).
Tension Demand - The factored or service tension force applied to the screw connection (kips).
Geometry - End and edge distances of the screw relative to the member boundaries (in).
Material Properties - Screw grade and member thickness, used to derive nominal stresses and bearing factors (ksi, in).

What it reports

Shear Capacity - The nominal shear strength derived from tilting and bearing, compared against the applied shear demand.
Tension Capacity - The nominal tension strength derived from pullout and pullover, compared against the applied tension demand.
Interaction Result - A verdict on the combined shear and tension state; if no tension demand exists, this field is omitted rather than reported as zero.
End Distance Check - A verification that the distance from the screw center to the member end meets the code minimums.
Edge Distance Check - A verification that the distance from the screw center to the member edge meets the code minimums.
Design Factor - The specific φ or Ω value applied to the nominal strengths, labeled according to the selected design method.

Code references

The engine cites AISI S100-16 w/S3-22 §J4.3 for screw shear, specifically addressing tilting and bearing. It cites AISI S100-16 w/S3-22 §J4.4 for screw tension, covering pullout and pullover. The module applies the LRFD resistance factor φ = 0.50 as a conservative reference value for screw connections, and the ASD safety factor Ω = 3.00 as printed in §J4.4.3.

Limits

This module is specific to screw connections and does not evaluate bolted or welded connections, which are handled by separate modules. It assumes US Customary units (kips, in, ksi) and does not support metric inputs. The module does not account for complex multi-screw interaction effects beyond the basic interaction check. Results are engineering aids; the engineer of record is responsible for the design.

This module ships in the desktop app

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