## Numerical on Rectangular water tank

**Ex.** Design a rectangular tank for a capacity of 80,000 liters.

**Sol.
**

Provide height of 3.5 m for tank with free board of 15 cm.

Effective height = **335 cm.**

Volume of tank to be required = 80,000 liters = **80,000,000 c.c**

Area of tank to be provided

Provide length of 600 cm. and breadth of 400 cm.

The wall of tanks are to be designed as continuous slab.

Bottom 1 m. of tank will be designed as cantilever.

Pressure at depth of 2.5 m.

**= 2,500 kg/m ^{2}**

Moments in the walls are found by moment distribution. As the frame is symmetrical about both axes moment distribution is done for one quarter of tank only.

B.M. at center of long span

**= 5417 kg. m.**

B.M. at center of shorter span

= 5000 – 5833 = **- 833 kg. m.**

Maximum B.M. = **5833 kg. m**

Effective depth required

Provide overall depth of 25 cm. with effective depth of 21.5 cm.