The correct answer is A. 10.
A long column is a column whose effective length is greater than 10 times its lateral dimension. This means that the column is slender and is more likely to buckle under load.
A short column is a column whose
effective length is less than 10 times its lateral dimension. This means that the column is stocky and is less likely to buckle under load.The effective length of a column is the length of the column that is actually resisting bending. It is calculated by taking into account the end conditions of the column.
The lateral dimension of a column is the dimension of the column that is perpendicular to the direction of the load.
The ratio of the effective length to the lateral dimension is a measure of the slenderness of the column. A slender column is more likely to buckle under load than a stocky column.
The following are the options of the question:
A. 10
B. 15
C. 20
D. 25
Option A is the correct answer. A column is regarded as long column if the ratio of its effective length and lateral dimension, exceeds 10.
Option B is incorrect. A column is not regarded as long column if the ratio of its effective length and lateral dimension, is less than or equal to 10.
Option C is incorrect. A column is not regarded as long column if the ratio of its effective length and lateral dimension, is less than or equal to 15.
Option D is incorrect. A column is not regarded as long column if the ratio of its effective length and lateral dimension, is less than or equal to 20.