In a plain concrete pedestal of M35 grade, the maximum bearing pressure at the base is found to be 40N/mm². Find the depth of footing, if the projection beyond the column is 300 mm.

Correct option is A

​$$\tan \alpha \le 0.9 \sqrt{\frac{100 q_0}{f_{ck}} + 1}$$​​
​$$\text{Given: } q_0 = 40 \text{ MPa}, \quad f_{ck} = 35 \text{ MPa}$$
$$\tan \alpha \le 0.9 \sqrt{\frac{100 \times 40}{35} + 1}$$
$$\tan \alpha \le 0.9 \sqrt{114.29 + 1}$$
$$\tan \alpha \le 9.66$$
$$\frac{d}{300} \ge 9.66$$
$$d \ge 300 \times 9.66$$
$$d \ge 2898 \text{ mm} \approx 3.1 \text{ m}$$​​​​​​​​