Riveted joints: For a diamond riveting pattern in a plate, the weakest net section typically passes through which row of rivet holes?

Introduction / Context:
Determining the weakest section in riveted joints is essential for safe design. In diamond riveting, the rivet count reduces stepwise toward the ends, and the net section (gross minus holes) governs tensile failure.

Given Data / Assumptions:

• Diamond pattern (progressive reduction of rivets).
• Plates in tension; failure by net-section tearing is possible.
• Uniform plate material and hole sizes.

Concept / Approach:
The weakest section is the one with the least net area. In diamond riveting, near the ends there are fewer parallel rows, creating narrower net paths through the first row. Thus, the critical section commonly passes through the first row of holes where the minimum net cross-section often occurs.

Step-by-Step Solution:
1) Identify gross section and subtract hole areas along possible failure lines.2) Compare net sections across rows; the end zones (first row) provide the least metal remaining.3) Conclude that the first-row section is typically the weakest in diamond riveting.

Verification / Alternative check:
Textbook examples of diamond riveting show net-section computations with the smallest net area through the first row, confirming design practice to reinforce ends or adjust pitch/hole layout.

Why Other Options Are Wrong:
Second/central rows generally retain more parallel load paths and hence larger net area.“One hole of end row only” does not fully represent the governing section in standard layouts.

Common Pitfalls:
Ignoring stagger efficiency and assuming the central row is always critical; in diamond patterns, end rows are often weaker.

Final Answer:
First row