Compression member – effective sectional area for design For a riveted or bolted compression member, the effective sectional area used in design is taken as:

Introduction / Context:
Compression members (columns, struts, lacing members) often have holes for rivets or bolts at their connections. These holes reduce the net cross-sectional area resisting compression. For working stress design and many practical checks, an effective (net) area is used to compute compressive stress and slenderness-based capacities.

Given Data / Assumptions:

• Member is built-up or connected using rivets/bolts.
• Holes pass through the section in the connection zone considered critical.
• We wish to determine the area adopted in stress computations.

Concept / Approach:
The effective compressive area is conservatively taken as the gross area minus the deduction for fastener holes. This aligns with the concept of net area used in tension members and avoids overestimating capacity in zones weakened by holes. Some codes allow limited exceptions if holes are filled tightly and are away from buckling-critical zones, but the standard safe approach is to deduct.

Step-by-Step Solution:

Verification / Alternative check:
Design examples in steel handbooks commonly subtract hole area for compression members at connections, matching the conservative practice embedded in older codes and many specifications.

Why Other Options Are Wrong:
Adding hole area is physically meaningless; multiplying areas has no dimensional coherence; ignoring holes can overrate capacity.

Common Pitfalls:
Using bolt nominal diameter instead of hole diameter; neglecting stagger correction where relevant; applying deductions over lengths where holes are absent.

Final Answer:
Gross sectional area minus the area of rivet (bolt) holes