CEW Solution .com
DESIGN OF RCC UG WATER TANK
 Purposes of UG Structures
 Types of UG Tank Structure
 Forces acting on UG RCC Tank
Video - 01
 UG Tank Behavior & Bending Moment Diagram
 Design Consideration (IS Provisions)
Video - 02
 Problem Specification
 Design Parameters & Inputs
Video - 03
 Load Calculation
 Staad Modelling & Analysis
Video - 04
 Design & Detailing of UG RCC Tank
Video - 05
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CONTENT
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PROBLEM
PROBLEM
Design of Under-ground Water Tank having capacity of 25000 gallon at Vadodara, Gujarat.
UG Tank
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
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SOIL REPORT
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
Min Grade of Concrete: M30

Level of Ground Water: NA

Type & Grade of Steel: CRS & 500D

Safe Bearing Capacity: 190 KN/m2

Cover for Wall: 50mm

Angle of Friction: 30°

Cover for Base Slab: 50mm (Top & Sides), 75mm
(Bottom)

Cover for Top Slab: 30 (Top & Sides), 50mm
(Bottom)

Density of Soil: 19KN/m3

Density of Water: 10KN/m3

Density of Concrete: 25KN/m3
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DESIGN INPUTS
SIZE FIXING
Capacity of Tank: 25000 Gallon

Thickness of Wall

Similar, 112,500 Liter, 113 m3 (Volume)

Consider D top to D bottom > 0.4

Consider 3.3m depth of tank

Span/thickness = 8.75

Required Area for tank = 34.25 m2

Thickness of wall at bottom = 412mm ≈ 450mm

Considering Square Tank

Assume Thickness of Wall at top = 300mm

Therefore, Length of Tank = 5.85m ≈ 6.0m

Considering 300mm free board, Height of wall = 3.6m

Length x Width x Height = 6.0m x 6.0m x 3.6m

Provided Capacity of Tank = 129.6 m3 > 113 m3

Thickness of Base Slab


Assume 450mm base slab thickness.
Thickness of Top Slab

Span of slab = 6m, difficult to pass Span/depth ration

Divide slab in 4 par ts by secondar y beam

Assume depth of top slab = 200mm
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
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LOAD CALCULATION

Dead Load: Self weight of Member (Calculated by Staad Pro)

Live Load: 1.5KN/m2 on Top Slab (Due to Pumping equipment

Water Pressure


Pressure on wall = 3.3 (h) x 10 ( γ) = 33 KN/m2 (Var ying Distributed Load)

Pressure on Base Slab = 3.3 (h) x 10 ( γ) = 33 KN/m2 (Uniformly Distributed Load)
Soil Pressure
Live Load
Surcharge
Pressure

Ka = 0.333 < 0.5, hence consider 0.5

Pressure on wall = 0.5 (Ka) x 3.6 (h) x 19 ( γ) = 34.2 KN/m2 (Var ying
Distributed Load)

Pressure on Base Slab = 3.6 (h) x 19 ( γ) = 68.4 KN/m2 (Uniformly
Distributed Load)
Soil
Pressu
re
Water
Pressure
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LOAD CALCULATION
Surcharge
Pressure
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THANK YOU