The effective length of a column effectively held in position and restrained in direction at one end, but neither held in position nor restrained in direction at the other end, is:
Try it first: pick an option, then read the explanation.
Correct answer: D. 2L
Asked in SSC JE 22/01/2018 (Evening)
Detailed Explanation
Code language: "held in position" = no sideways movement; "restrained in direction" = no rotation. An end with both is fixed; an end with neither is free.
Why “2L” Is Correct
So this is a fixed–free column, and its effective length is 2L (theory and IS 800 alike).
| Restraint at the two ends (IS 800 Table 11 / IS 456 Table 28) | Theoretical le | Recommended le |
|---|---|---|
| Held in position and restrained in direction at both ends (fixed–fixed) | 0.5L | 0.65L |
| Fixed at one end, held in position but free to rotate at the other (fixed–hinged) | 0.7L | 0.80L |
| Held in position at both ends, free to rotate (hinged–hinged) | 1.0L | 1.0L |
| Fixed at one end; other end restrained in rotation but free to translate (sway) | 1.0L | 1.2L |
| Fixed at one end; other end free (not held in position nor restrained in direction) | 2.0L | 2.0L |
| Hinged at one end; other end restrained in rotation but free to translate | 2.0L | 2.0L |
Code values are larger than the theoretical ones for restrained ends because perfect fixity is never achieved in practice.
Why the Other Options Are Wrong
- A. L: L corresponds to both ends held in position but free to rotate (hinged–hinged).
- B. 0.67L: 0.67L is close to the fixed–fixed code value (0.65L).
- C. 0.85L: 0.85L is not a standard value for these conditions; the free end makes le larger than L.
Key Point
Fixed at one end, free at the other: le = 2L.
Key Concepts for Students
- Translate code phrases into fixed / hinged / free first.
- "Held in position" = translation prevented.
- "Restrained in direction" = rotation prevented.
Practice more: this is question 17 in Columns and Struts MCQs – Part 2. Try the whole set and check every answer instantly.