The equivalent length of a column of length l fixed at both ends is:
Try it first: pick an option, then read the explanation.
Correct answer: A. 0.5l
Asked in SSC JE 2012
Detailed Explanation
With rotation prevented at both ends, the buckled shape has inflection points at l/4 from each end.
Why “0.5l” Is Correct
The equivalent length is 0.5l (theoretical; IS 800 recommends 0.65l for design).
Why the Other Options Are Wrong
- B. 0.7l: 0.7l is fixed–hinged (l/√2).
- C. l: l is hinged–hinged.
- D. 2l: 2l is fixed–free.
Key Point
Fixed–fixed: le = 0.5l (theory), 0.65l (code).
Key Concepts for Students
- Decimal forms: 0.5, 0.707, 1, 2.
- Code values account for imperfect fixity.
- Shortest le gives the highest load.
Practice more: this is question 25 in Columns and Struts MCQs – Part 2. Try the whole set and check every answer instantly.