Correct Answer - Option 4 : Less than 8
Explanation:
Short Column - Short columns are those whose slenderness ratio is less than 32 or length to diameter ratio is less than 8. Such columns are always subjected to direct compressive stress only.
Long Column - Long columns have a slenderness ratio more than 120 or length to diameter ratio more than 30.
Modes of failure of column
- In the case of short column, the failure occurs by crushing of the material under the compression yield stress.
- In the case of a long column, the failure occurs by buckling. i.e By lateral deflection of the bar
- Intermediate column fails in combined Buckling and Crushing.
Note:
Euler theory is only applicable for long column
Rankine theory considers combine crushing and buckling mode of failure.