Compression Members MCQ with answer and solution

Concept

Most efficient section for compression members

Formula

NONE

Step-by-step solution

1. The efficiency of a compression member depends on its radius of gyration and torsional resistance. 2. Tubular sections have uniform mass distribution about both axes, providing an equal maximum radius of gyration in all directions and high torsional rigidity. 3. Therefore, tubular sections are considered the best compression member section. Answer: D

Explanation

An ideal compression member section has equal strength and rigidity about all centroidal axes to resist buckling in any direction. Tubular sections feature circular symmetry, giving them an identical moment of inertia and maximum radius of gyration around every axis. Consequently, option D is the best compression member section due to its uniform stability and high buckling resistance.

Why the other options are wrong

A) Single angle sections have a low radius of gyration and high eccentricity, making them weak in axial compression. B) Double angle sections are asymmetrical about one principal axis, reducing their compressive efficiency relative to hollow shapes. C) I-sections have unequal radii of gyration about their principal axes, making them susceptible to buckling along the weak axis.

Shortcut

Tubular sections have equal radius of gyration in all directions, making them ideal compression members.

Common mistake

Choosing I-sections or angle sections instead of tubular sections, which offer a uniform radius of gyration in all directions.