A short column 20 cm × 20 cm in section is reinforced with 4 bars whose area of cross section is 20 sq. cm. If permissible compressive stresses in concrete and steel are 40 kg/cm2 and 300 kg/cm2, the Safe load on the column, should not exceed A. 4,120 kg B. 41,200 kg C. 4,12,000 kg D. None of these

[amp_mcq option1=”4,120 kg” option2=”41,200 kg” option3=”4,12,000 kg” option4=”None of these” correct=”option1″]

The correct answer is A. 4,120 kg.

The safe load on the column is the load that will not cause the column to fail. The failure of a column is caused by either compressive or tensile stress exceeding the permissible stress. In this case, the permissible compressive stress in concrete is 40 kg/cm2 and the permissible compressive stress in steel is 300 kg/cm2.

The area of the column is 20 cm × 20 cm = 400 cm2. The area of the steel reinforcement is 4 bars × 20 cm2/bar = 80 cm2.

The safe load on the column is therefore:

400 cm2 × 40 kg/cm2 + 80 cm2 × 300 kg/cm2 = 4,120 kg.

Option B is incorrect because it is the safe load on the column if the permissible compressive stress in concrete was 300 kg/cm2. Option C is incorrect because it is the safe load on the column if the permissible compressive stress in steel was 400 kg/cm2. Option D is incorrect because it is not a possible answer.