Designing weld groups subjected to eccentric loads is a common challenge in steel construction, especially in connections like brackets, base plates, and lifting lugs. Unlike concentric loading, eccentric forces introduce additional torsion and bending moments that must be properly accounted for. This Eccentrically Loaded Weld Group Analysis Excel Sheet makes that process faster, safer, and more accurate.
The Challenge of Eccentric Weld Loading
When a load is applied at a distance from the centroid of a weld group, it creates a moment arm that induces a torsional component on the weld pattern. Every element of the weld group then carries a combination of direct shear (from the applied force) and torsional shear (from the eccentric moment). The most highly stressed weld element — the critical location — determines the required weld size.
This situation arises constantly in practice: bracket connections to columns, shelf plate supports, corbels with welded connections, and any attachment where load is applied off-centre from the weld centroid.
Analysis Methods Implemented
This sheet implements the Elastic (Vector) Method per AISC-ASD 9th Edition:
- The weld group is treated as a line with unit throat
- The centroid of the weld group is located geometrically
- The polar moment of inertia (Ip) of the weld pattern is calculated
- Direct shear stress and torsional shear stress are computed at each weld segment
- Resultant stress is found by vector addition and compared to the allowable shear stress
Weld Group Patterns Supported
- Vertical weld (single line)
- Horizontal weld (single line)
- L-shaped weld (two lines)
- C-shaped weld (three sides)
- Rectangular closed weld group (four sides)
Sheet Outputs
- Weld group centroid coordinates
- Polar moment of inertia Ip
- Direct and torsional shear components
- Resultant stress at critical point
- Required weld size (fillet weld leg) for the applied loading
- Pass/fail check against AISC-ASD allowable weld stress
