For the same cross-sectional area, which column shape typically carries more load?

• A. Square
• B. Rectangular
• C. Circular
• D. Triangular

Answer: (C)

When a column carries load in compression, buckling resistance often limits how much load it can take. The key factor here is the moment of inertia of the cross-section: the larger the moment of inertia about the axis of buckling, the more resistant the member is to lateral deflection. For a given cross-sectional area, the circular shape has the largest moment of inertia about any centroidal axis, which means it stays straighter longer under load. Therefore, a circular cross-section can carry a higher axial load before buckling than square, rectangular, or triangular shapes with the same area. If buckling isn’t the controlling factor, material strength and area govern the load, but in typical slender-column scenarios, the circular shape is most efficient for carrying load.