Net section allowance: for a tension member made of four angles with a plate acting as a web (built-up section), how many holes should be deducted in computing the net area across the critical section?

Introduction / Context:
When calculating the net area of a built-up tension member, deductions are made for fastener holes crossing the critical section. The number of holes to deduct depends on how many component parts and fastener lines pass through that section, ensuring a conservative estimate of the remaining metal resisting tension.

Given Data / Assumptions:

• Member consists of four angles and one web plate, fastened to a gusset.
• Critical section intersects one line of holes in each connected component.

Concept / Approach:
For a typical connection where each of the four angles contributes via one line of fasteners and the web plate also has one line, the net section deduction takes one hole per line intersected. Thus, deduct one hole for each angle and one hole for the web plate across the critical plane. (If multiple lines per component are crossed, deductions increase accordingly.)

Step-by-Step Solution:
Identify components crossing the section: 4 angles + 1 web plate. Assume one line of fasteners per component at the critical section. Deduct holes accordingly: one per angle (4 holes) and one for the web (1 hole). Select the option that reflects one hole per angle and one hole for the web.

Verification / Alternative check:
Connection detailing conventions and exam problems typically assume one rivet/bolt line per component unless otherwise stated; net area examples mirror this deduction rule.

Why Other Options Are Wrong:

• Two-hole deductions per component presume two lines or stagger across the section, which is not given.
• None: deductions are required whenever the critical section crosses fastener holes.

Common Pitfalls:

• Forgetting to add zig-zag correction when the failure path is staggered.
• Mixing gross and net areas in tension capacity checks.

Final Answer:
One hole for each angle and one hole for the web.