How to use the weld group stress calculator
An eccentrically loaded fillet weld group carries direct shear and torsion at the same time. This tool treats each weld as a line of unit throat, builds the total length, centroid, and polar moment of inertia J for the selected layout, and applies the elastic vector method to find the peak resultant stress. The centroid shifts toward whichever side has more weld, so the real lever arm is measured from the load point to the centroid rather than to the support face.
The peak stress is the vector sum of two parts. Direct shear is P divided by total weld length and is the same everywhere, while the torsional component M·c/J grows with distance from the centroid. The tool tests every weld end point and reports the largest resultant. Required leg size is that value divided by the design strength per inch of leg, 0.75 × 0.6·FEXX × 0.707, which for E70XX electrodes gives the familiar 1.392 kip per inch per sixteenth of leg from AISC 360 Section J2.
The result is a weld metal check only. Base metal strength at the joint, the minimum fillet sizes of Table J2.4, effective throat adjustments, and whether end returns are used all still have to be confirmed. A load applied perpendicular to the weld plane or a three-dimensional eccentricity falls outside this two-dimensional model. Have a licensed structural engineer review bracket and connection details that carry primary load.
Frequently Asked Questions
Treating each fillet weld as a line with a 1 in throat makes the resulting stress come out as force per inch of weld, which converts directly into a required leg size. This is the standard elastic vector method used for eccentrically loaded weld groups.
No. AISC Table J2.4 sets minimum fillet sizes based on the thickness of the thicker part joined, and the base metal strength at the weld also has to be checked. A calculated 0.13 in leg still has to be increased to the code minimum for thick plate.