Fillet Weld Size Limits and Effective Throat (AISC 360 J2.2b)

What size the code allows before the strength calc even applies.

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Checked against published worked examples from: AISC.

Details, formula, and sources

ScopeThe Table J2.4 minimum leg from the THINNER part joined (so the weld cools slowly enough not to crack), the J2.2b maximum along an edge (full thickness under 1/4 in, thickness minus 1/16 at or over - so the edge is not melted away), the equal-leg throat 0.707 w, and the 4w minimum length. A 1/2 to 3/8 in joint takes a 3/16-to-5/16 window, and a chosen 1/4 in weld carries a 0.177 in throat. The numbers a WPS is written to; a fillet-weld strength check assumes you already picked them. A fabrication aid; AWS D1.1 and the engineer govern.

Formula or tablemin_leg from Table J2.4 by the thinner part (1/8 to 5/16 in brackets); max_leg = t (t < 1/4 in) or t - 1/16 (t >= 1/4 in) along an edge; te = 0.707 w; min length = 4 w.

Source and editionThe AISC 360-22 Table J2.4 minimum fillet-weld size, the J2.2b maximum size along an edge, the equal-leg effective throat, and the four-times-leg minimum length, by name.

Free accessAISC 360 is free to read at aisc.org (Specification for Structural Steel Buildings); Table J2.4 and the J2.2b limits are in the published specification.

What governsEstimate. AHJ and licensed professional govern.

API field namest1_in, t2_in, w_in, min_leg_in, max_leg_in, te_in, min_len_in

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