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

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.