Question 1

How is fillet weld strength calculated per AISC 360-22?

Accepted Answer

φRn = φ × 0.6 FEXX × Aw per unit length, where φ = 0.75, FEXX is electrode strength (typically 70 ksi = 485 MPa for E70XX), and Aw = 0.707 × weld size × length (throat × length).

Question 2

What is the directional strength increase for fillet welds in AISC 360-22?

Accepted Answer

Per AISC 360-22 Section J2.4, weld loaded at angle θ to the weld axis: Rn = 0.6 FEXX (1.0 + 0.5 sin^1.5 θ) × Aw. Welds loaded transversely (θ=90°) are 50% stronger than longitudinally loaded welds (θ=0°).

Question 3

What is the minimum fillet weld size per AISC 360-22?

Accepted Answer

Per AISC 360-22 Table J2.4, minimum weld size depends on the thickest part joined: 3 mm for t ≤ 6 mm; 5 mm for 6 < t ≤ 13 mm; 6 mm for 13 < t ≤ 19 mm; 8 mm for t > 19 mm.

Question 4

What is the maximum fillet weld size per AISC 360-22?

Accepted Answer

Per AISC 360-22 Section J2.2b, maximum weld size = plate thickness – 2 mm for plates 6 mm or thicker (to ensure fusion without burning through the edge). For plates thinner than 6 mm, max = plate thickness.

Question 5

What is a groove weld and when is it used instead of a fillet weld?

Accepted Answer

A groove weld fills a prepared joint between butting members (CJP: complete joint penetration, or PJP: partial joint penetration). CJP groove welds develop the full base metal strength and are used in moment-resisting connections where fillet welds would be insufficient.

Step	Formula	Substitution	Result
te	0.707·w	0.707×6	4.2 mm
Fnw	0.6·FEXX(1+0.5sin^{1.5}θ)	0.6×482×(1+0)	433.8 MPa
φRn	φ·Fnw·Aw	0.75×433.8×849	276.1 kN

Step	Formula	Substitution	Result
te	0.707·w	0.707×6	4.2 mm
Fnw	0.6·FEXX(1+0.5sin^{1.5}θ)	0.6×482×(1+0)	433.8 MPa
φRn	φ·Fnw·Aw	0.75×433.8×849	276.1 kN

Weld Connection

Fillet Weld Design

Load

Weld

Fillet Weld Connection

Given: