Reinforcement area required for an opening must be at least twice the removed area. If removed area is 18 in^2, minimum reinforcement area is?

• A. 18 in^2
• B. 54 in^2
• C. 72 in^2
• D. 36 in^2

Answer: (D)

Openings in a shell weaken the local area and create stress concentrations around the edge. To restore strength and maintain similar load-carrying behavior, the reinforcement surrounding the opening must be at least twice the area that was removed. This rule helps ensure the plate around the hole has enough material to carry the stresses and distribute them properly, preserving structural integrity.

If the removed area is 18 square inches, doubling it gives a minimum reinforcement area of 36 square inches. So the smallest reinforcement to meet this requirement is 36 square inches. The other options would provide more material than the minimum but aren’t necessary under this rule.