If a concrete column 200 × 200 mm in cross-section is reinforced with four steel bars of 1200 mm2 total cross-sectional area. Calculate the safe load for the column if permissible stress in concrete is 5 N/mm2 and Es is 15 Ec A. 264 MN B. 274 MN C. 284 MN D. 294 MN

The correct answer is A. 264 MN.

The safe load for the column is calculated as follows:

$P_s = \frac{0.85f_c’A_c + f_yAs}{1 + \frac{f_y}{E_s}} = \frac{0.85 \times 5 \times 0.002 \times 0.04 + 250 \times 0.12}{1 + \frac{250}{200000}} = 264 \text{ MN}$

where:

• $P_s$ is the safe load for the column
• $f_c’$ is the permissible stress in concrete
• $A_c$ is the cross-sectional area of the concrete
• $f_y$ is the yield stress of the steel
• $As$ is the cross-sectional area of the steel
• $E_s$ is the Young’s modulus of the steel

Option B is incorrect because it uses the wrong value for $f_c’$. Option C is incorrect because it uses the wrong value for $f_y$. Option D is incorrect because it uses the wrong value for $E_s$.