FILLET WELDS (AWS)

Fillet welds are sized by their throat dimension t = 0.707·w where w is the leg length. AWS D1.1 limits allowable shear stress on the throat to 0.30·Fexx for the electrode tensile strength. For eccentric loads (load applied off the weld-group centroid), the elastic vector method computes weld stress as the combination of direct shear plus a polar-moment shear that varies around the group. Treat each weld segment as a line and compute J_w accordingly.

• t = 0.707 · w
• τ_allow = 0.30 · Fexx
• τ_direct = P / A_w
• τ_torsion = T·r / J_w
• τ_resultant = sqrt(τ_direct² + τ_torsion² + 2τ_d·τ_t·cosθ)

References & StandardsAWS D1.1, AISC 360 Ch. J

Use for any structural weld: brackets, lifting lugs, weldments, pressure-vessel attachments. For pure axial or shear load, throat sizing is direct. For eccentric loads, build the weld group and compute the resultant on the highest-stressed point. Specify electrode (E70xx, E80xx) consistent with base metal. Avoid intermittent welds in fatigue applications.