# Detail specifications of RCC rectangular water tank

If the storage strength is minor, the rectangular tanks are most suitable.

To make it cost-effective, the rectangular tanks should be square in shape.

It should be kept in mind that the longer side should not be larger than twice the smaller side.

Moments should occur in two directions of the wall i.e. both in horizontal and in vertical direction.

Perfect analysis is not possible and design is created with approximate methods.

If the length of the wall is higher with regard to its height, the moments mainly remain in vertical direction i.e. the panel bends as vertical cantilever.

To design a tank with size (12 m x 5 m x 4 m), the bottom of tank should be 12 m over the ground level. The tank should be covered at top. SBC of soil = 150 kn/M2. The grade of concrete should be M20.

A) Design of roof slab

Reinforcement of slab Specification Size Reinforcement details Top slab 12 m x 5 m Long span 8mm Ø @300mm c/c Short span 12mm Ø @1500mm c/c

B) Design of longer and shorter side walls

Specification Size Reinforcement details Longer side wall 12m x 4m Long span 8mm Ø @300mm c/c Short span 1. +ve bending moment 12mm Ø @90mm c/c 2. –ve bending moment 20mm Ø @110mm c/c Shorter side wall 5m x 4m Long span 1. At top 12mm Ø @170mm c/c 2. At bottom 12mm Ø @80mm c/c Short span 1. At supports 12mm Ø @70mm c/c 2. At middle 10mm Ø @80mm c/c

C) Design of beams

Beam I 480mm x 300mm Main reinforcement 3 bars of 20mm Ø & 3 bars of 32 mm Ø Stirrups 12mm Ø @50mm c/c (near support) 12mm Ø @80mm c/c (near middle) Beam II 480mm x 300mm Main reinforcement 3 bars of 20mm Ø Stirrups 8mm Ø @300mm c/c Beam III 480mm x 300mm

Main reinforcement

1. Span AB - 3 bars of 12mm Ø

2. Span BC - 2 bars of 12mm Ø

Stirrups - 8mm Ø @300mm c/c

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