Correct Answer - Option 2 : γHD/2
Concepts
For a circular water tank resting on the ground and has a flexible joint at base, the formula for hoop tension calculation is given as:
\(\sigma_h = \frac{pd}{2} \)
Where,
p is the water pressure inside tank
d is the diameter of tank
Further, the water pressure is given as:
P = γ × H
Where, γ is the unit weight of water
H is the height up to which water is filled in tank.
Substituting equation 2 in equation 1, we get hoop tension is:
\( \sigma_h = \frac{\gamma Hd}{2} \)
Additional Information
For the design of a circular water tank following points should be remembered:
1. Water tank is designed as a crack-free structure to eliminate any leakage.
2. Permeability of concrete is directly proportional to the water-cement ratio. Therefore, we need to keep increasing the cement content to a very high value in order to reduce the water-cement ratio.
3. Cement content ranging from 330 Kg/m3 to 530 Kg/m3 is recommended in order to keep shrinkage low.