Which describes the effective area of a plug or slot weld?

• A. The cross-sectional area of the weld material
• B. The area of the hole in the plane of the faying surface
• C. The surface area of the weld face
• D. The depth of the weld cavity

Answer: (C)

The key idea is identifying what portion of the weld actually carries the load in the joint. For plug or slot welds, the load is transferred across the weld face that sits in the plane of the faying surfaces. That exposed weld-face area is the surface that resists shear between the joined members, so it defines the effective area.

The other descriptions don’t represent the load-carrying surface: the cross-sectional area of the weld is not the surface through which shear acts, the hole area is just the opening and not the actual resisting surface, and the depth is a dimension, not an area.