Intermittent Fillet Weld Schedule (AISC J2 / AWS)
When a required continuous fillet is smaller than the practical minimum weld.
Example
You enter
- Required continuous fillet size (in) 0.1875
- Intermittent (stitch) fillet size (in) 0.3125
- Weld increment length (in) 3
You get
- Fraction of length to weld 0.6
- Pitch (in) 5
- Minimum increment check min 1.50 in -- increment OK
No published worked example is on file for this calculation. It is checked against a hand-worked derivation of its method and an independent reference test.
Details, formula, and sources
ScopeSizes the intermittent (stitch) schedule that matches it: weld a fraction w_req/w of the length at the larger stitch size, pitch = increment / fraction, each increment at least the greater of 4 x the weld size or 1.5 in (AISC 360 J2.2b). A 3/16 in required weld done as 5/16 in stitches means welding 60% of the length; a 3 in increment gives a 5 in pitch (weld 3, skip 2) and clears the 1.5 in minimum. Maximum spacing and end returns are separate checks. A design aid, not a substitute for the engineer of record.
Formula or tablefraction = w_req / w_intermit; pitch = increment / fraction; min_increment = max(4 x w_intermit, 1.5 in); ok = increment >= min_increment.
Source and editionAISC 360 §J2.2b (intermittent fillet welds, minimum length) and AWS D1.1 Structural Welding Code - Steel, by name.
Free accessFirst-principles strength-match geometry; the AISC 360 minimum-length rule (4 x weld size, not less than 1-1/2 in) is public.
What governsEstimate. AHJ and licensed professional govern.
API field namesw_req_in, w_intermit_in, increment_in, fraction, pitch_in, min_incr_in
- Strength match weld a fraction w_req/w of the length; pitch = increment / fractionweld strength-match geometry
- Minimum increment each segment at least the greater of 4 x weld size or 1-1/2 inAISC 360 §J2.2b
- Spacing separate maximum longitudinal spacing and end returns are separate code checksAISC 360 §D4 / §E6 / AWS D1.1