Riveted Joint – Net section in a zig-zag pattern Two 150 mm × 10 mm plates joined by three 20 mm rivets in zig-zag; pitch = 75 mm, gauge = 60 mm, allowable tensile stress = 150 MPa. Maximum allowable tensile force?

Introduction / Context:
In tension, a riveted (or bolted) plate connection fails on the weakest net section. For zig-zag riveting, the net width is increased by a stagger correction. This problem checks the correct evaluation of net section and allowable tensile capacity using working stress design.

Given Data / Assumptions:

• Plate width b = 150 mm, thickness t = 10 mm.
• Three rivets of nominal diameter 20 mm arranged in zig-zag.
• Pitch p = 75 mm, gauge g = 60 mm.
• Allowable tensile stress σ_allow = 150 MPa (N/mm2).
• Hole diameter d0 ≈ d + 1.5 mm → 21.5 mm (typical practice).

Concept / Approach:

For a zig-zag path cutting two holes on alternate rows, net width = b − n * d0 + Σ(p^2 / (4 * g)) for each staggered pair crossed. Here, n = 2 holes and there is one stagger term because the critical section passes diagonally through adjacent rows.

Step-by-Step Solution:

Verification / Alternative check:

Any section cutting three holes (without adequate stagger terms) gives a lower net width due to excessive deductions and is typically not the governing path here with the given layout.

Why Other Options Are Wrong:

195.00 and 192.75 kN round off or under-estimate due to ignoring the stagger correction or rounding area too early; 225.00 kN exceeds the allowable capacity for the given dimensions and stress.

Common Pitfalls:

Using nominal rivet diameter instead of hole diameter for deductions, or forgetting the stagger addition p^2/(4g).

Final Answer:

195.66 kN