Built-up Columns MCQ with answer and solution

Concept

Advantages of using built-up steel sections

Formula

NONE

Step-by-step solution

1. Built-up sections are fabricated by combining standard rolled sections when single sections are inadequate. 2. They allow for achieving a large cross-sectional area and tailored depth or shape to resist heavy loads. 3. Spacing the components increases the moment of inertia and radius of gyration, enhancing buckling resistance. 4. Therefore, built-up sections provide all of the above benefits. Answer: D

Explanation

Built-up sections are fabricated by combining standard structural shapes and plates when individual rolled sections cannot support heavy loads. They allow engineers to achieve larger cross-sectional areas, custom section depths, and substantially increased radii of gyration to resist buckling. Because built-up members satisfy all these design needs simultaneously, option D is the correct answer.

Why the other options are wrong

A) Large cross-sectional area is only one of multiple structural advantages provided by built-up sections. B) Custom shapes and depths represent just one beneficial feature of fabricated built-up members. C) High radius of gyration aids in resisting buckling, but it is not the sole reason for using built-up sections.

Shortcut

Built-up sections are custom-made to increase area, depth, and radius of gyration.

Common mistake

Selecting only one specific advantage instead of recognizing that built-up sections provide area, shape, and gyration benefits.