The correct answer is $\boxed{\text{B}}$.
A column is a structural element that is designed to support loads primarily by compression. The crippling load of a column is the maximum load that the column can support before it buckles.
The crippling load of a column depends on the following factors:
- The material of the column
- The cross-sectional shape of the column
- The length of the column
- The end conditions of the column
The end conditions of a column refer to how the column is supported at its ends. A column with both ends fixed is more rigid than a column with both ends hinged. This is because a column with both ends fixed cannot rotate at its ends, while a column with both ends hinged can rotate at its ends.
The ratio of crippling loads of a column having both the ends fixed to the column having both the ends hinged is 2. This means that a column with both ends fixed can support twice the load of a column with both ends hinged.
Here is a diagram that shows the different end conditions of a column:
[Diagram of a column with different end conditions]
The following is a brief explanation of each option:
- Option A: 1. This is incorrect because the crippling load of a column with both ends fixed is greater than the crippling load of a column with both ends hinged.
- Option B: 2. This is the correct answer because the crippling load of a column with both ends fixed is twice the crippling load of a column with both ends hinged.
- Option C: 3. This is incorrect because the crippling load of a column with both ends fixed is not three times the crippling load of a column with both ends hinged.
- Option D: 4. This is incorrect because the crippling load of a column with both ends fixed is not four times the crippling load of a column with both ends hinged.