As per IS 800 : 2007, the recommended value of an effective length for compression members of constant dimensions effectively held in position at both ends, but not restrained against rotation, is
- A1·00LCorrect
- B1·20L
- C1·50L
- D2·00L
Solution
Concept
Effective length factors (IS 800 Table 11)
Step-by-step solution
1. Held in position at both ends but free to rotate = pinned–pinned. 2. Effective length = 1.0 L.
Explanation
A column hinged at both ends buckles in a single half sine wave of length L, so the effective length equals the actual length.
Why the other options are wrong
1.2 L, 1.5 L and 2.0 L apply to conditions with sway or end translation.
Shortcut
Pinned–pinned = 1.0 L.
Common mistake
Choosing 0.65 L.
Correct answer: A) 1·00L