Tacking rivets – purpose and detailing rules in built-up members Which statements about tacking rivets are correct for compression members composed of components placed back-to-back?

Introduction / Context:
Tacking rivets (or bolts) are secondary fasteners used in built-up members to prevent local buckling and maintain component alignment. They are not intended to carry primary design load.

Given Data / Assumptions:

• Compression member composed of two elements placed back-to-back (e.g., double angles).
• Standard detailing limits expressed using t = thickness (mm).
• Working-stress method context.

Concept / Approach:
Tacking rivets are placed to stitch components so that they act as a unit. Codes set maximum spacing limits (e.g., not exceeding 12 t or 200 mm, whichever is less). Because they are for stitching, their contribution is ignored in capacity calculations.

Step-by-Step Solution:
Check spacing rule → use when separation exceeds 12 t or 200 mm.Function → prevent separation, ensure built-up action; not counted in strength.Applicability → provided along the full length of built-up compression members.

Verification / Alternative check:
These provisions appear consistently across classic handbooks and specifications for riveted/bolted built-up members.

Why Other Options Are Wrong:

• “None of the above” is incorrect because all listed statements reflect standard practice.

Common Pitfalls:
Counting tacking rivets toward load capacity or exceeding maximum permitted spacing can compromise member stability.

Final Answer:
All the above