As per IS 800: 2007, which of the following statements is correct regarding the maximum slenderness ratio?
- AThe maximum slenderness ratio of a member carrying compressive loads resulting from dead load and imposed loads should not exceed 180.Correct
- BThe maximum slenderness ratio of a member carrying compressive loads resulting from dead load and imposed loads should not exceed 200.
- CThe maximum slenderness ratio of a member carrying compressive loads resulting from dead load and imposed loads should not exceed 250.
- DThe maximum slenderness ratio of a member carrying compressive loads resulting from dead load and imposed loads should not exceed 350.
Solution
Concept
IS 800:2007 limits KL/r for a member carrying compression from dead load and imposed load to 180.
Formula
λ = KL/r ≤ 180
Step-by-step solution
1. Find the type of member: it carries compression from dead load (DL) and imposed load (LL). 2. Recall the IS 800:2007 limits on maximum effective slenderness ratio (KL/r). 3. For compression from DL and LL, the limit is 180. 4. So the answer is (A).
Explanation
A long, thin compression member can buckle easily. To prevent this, IS 800:2007 limits its slenderness. For a member carrying compression from dead load and imposed load, KL/r must not be more than 180.
Why the other options are wrong
B: 200 is not the limit for this member. C: 250 is for compression from wind or earthquake forces only. D: 350 is for a tension member that may get reversal of stress due to wind or earthquake.
Shortcut
Remember 180 (DL + LL compression), 250 (wind/EQ compression), 300 (ordinary tension), 350 (tension with reversal), 400 (tension member pre-tensioned).
Common mistake
Students mix up 180 with 250. The 250 limit is only when compression comes from wind or earthquake.
Correct answer: A) The maximum slenderness ratio of a member carrying compressive loads resulting from dead load and imposed loads should not exceed 180.