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Welded Connections

Various types of welds may be used to joint cold-formed steel members such as groove welds in butt joints, fillet welds, flare groove welds, arc spot welds, arc seam welds, and  resistance welds. The nominal strength, Pn, for several of these weld types is given in this article. More complete information may be found in the AISI Specification. The provisions given are applicable where the thickness of the thinnest part connected is 0.18 in (4.57 mm) or less. For thicker parts, refer to the AISC Specification. Welders and welding procedures should be qualified in accordance with specifications of the American Welding Society (AWS)

Groove Welds in Butt Joints

For tension or compression, the nominal strength is

Fillet Welds

Fillet welds are considered to transmit longitudinal and transverse loads with shear stresses.
For these welds, the nominal strength is the smaller of the limit based on weld strength and that based on the strength of the connected part.

Arc Spot Welds

Arc spot welds, also know as puddle welds, are made in the flat welding position to join sheets to thicker members. They are made by using the arc to burn a hole in the top sheet (or sheets), then depositing weld metal to fill the hole and fuse it to the underlying member.
Thus, no hole need be punched in the sheet. Such welds should not be made where the top sheet (or sheets) is over 0.15 in (3.81 mm) thick. Where the thickness of the sheet is less than 0.028 in (0.711 mm), a washer should be used on top of the sheet and the weld made inside this washer. The washer should have a thickness of 0.05 to 0.08 in (1.27 to 2.03 mm), with a prepunched hole of 0.375 in (9.53 mm) diameter. Arc spot welds are specified by minimum effective diameter of fused area, de , and the minimum is 0.375 in (9.53 mm). The AISI Specification gives provisions for both shear and tension (uplift) loadings.
For shear, the nominal strength is the smaller of the limit based on the strength of the  weld and that based on the strength of the connected part.

Also for arc spot welds in shear, the edge distance must be sufficient. AISI requires that the clear distance from the edge of a weld to the end of a member be not less than 1.0d.
Furthermore, the distance measured in the line of force from the centerline of a weld to the nearest edge of an adjacent weld, or to the end of the connected part toward which the force is directed, be not less than 1.5d and also not less than the following:
For ASD


force), Pu  required strength per weld (factored force), t  thickness of thinnest connected sheet, and Fsy  specified yield stress.
For tension, such as caused by uplift, the nominal strength is the smaller of the limit based on the strength of the weld and that based on the strength of the connected part.
For weld strength,

Resistance Welds

Resistance welds, often referred to as spot welds, are made by placing two lapped sheets between opposing electrodes that press the sheets together. The weld is created by the heat generated by resistance to current flow. The nominal shear strength is determined as follows, based on the thickness of the thinnest sheet joined, t.
In traditional units: