Use of lug angles in steel connections: which statements are correct regarding where lug angles are typically used or avoided?

Introduction / Context:
Lug angles are short auxiliary angles used to attach the outstanding leg of an angle (or outstanding flange/leg of other sections) directly to a gusset, improving load transfer and reducing eccentricity.

Given Data / Assumptions:

• Single-angle members often have one leg outstanding from the gusset plate.
• Double-angle members back-to-back have more balanced connection lines and generally do not need lug angles.
• Channel members with an outstanding flange may use lug angles in some layouts.

Concept / Approach:
For single-angle members, lug angles help bring the line of action closer to the centroid and increase the effective connected area. When two angles are back-to-back (double angles), connections are typically symmetrical, so lug angles are unnecessary. Channels can use lug angles to connect the outstanding elements effectively.

Step-by-Step Solution:

Verification / Alternative check:
Design handbooks show detailing examples where lug angles are recommended for single angles and some channels but omitted for double angles.

Why Other Options Are Wrong:
Individually selecting only one statement ignores the broader practice; hence “All the above” is correct.

Common Pitfalls:
Failing to check lug angle capacity and bolt group design; ignoring the additional fabrication and inspection complexity.

Final Answer:
All the above