Planning analysis design the overhead circular water tank in seerapalayam panchayat

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PLANNING ANALYSIS AND DESIGN OF
OVERHEAD CIRCULAR WATER TANK
A PROJECT REPORT
Submitted by
MUTHUKRISHNAN S (720314103025)
RAMAIAH R M (720314103037)
RAMCHAND M T (720314103038)
SUBASH T (720314103051)
in partial fulfillment for the award of the degree
Of
BACHELOR OF ENGINEERING
IN
CIVIL ENGINEERING
AKSHAYA COLLEGE OF ENGINEERING AND TECHNOLOGY
ANNA UNIVERSITY :: CHENNAI 600 025
OCTOBER-2017

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PLANNING ANALYSIS AND DESIGN OF
OVERHEAD CIRCULAR WATER TANK
A PROJECT REPORT
Submitted by
RAMAIAH R M (720314103037)
RAMCHAND M T (720314103038)
SUBASH T (720314103051)
in partial fulfillment for the award of the degree
Of
BACHELOR OF ENGINEERING
IN
CIVIL ENGINEERING
AKSHAYA COLLEGE OF ENGINEERING AND TECHNOLOGY
ANNA UNIVERSITY :: CHENNAI 600 025
OCTOBER-2017

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BONAFIDE
ANNA UNIVERSITY: CHENNAI 600 025
BONAFIDE CERTIFICATE
Certified that this project report “PLANNING ANALYSIS AND DESIGN OF
OVERHEAD CIRCULAR WATER TANK” is the bonafide work done by
……………………………………………………………………………………
Reg No…………………………………………… of final year Civil Engineering
(2017-2018) who carried out the project work under my supervision.
SIGNATURE SIGNATURE
Mr.K.THIRUNAVUKKARASU, M.E.,
HEAD OF THE DEPARTMENT
ASSISTANT PROFESSOR
Mr.RATHNAVEL.PON, M.E.,
SUPERVISOR
ASSISTANT PROFESSOR
Department of Civil Engineering,
Akshaya College of Engineering
and Technology,
and Technology,
Kinathukadavu. Kinathukadavu.
Submitted for the project viva-voice examination held on …………………….
Internal Examiner External Examiner

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CERTIFICATE
ANNA UNIVERSITY: CHENNAI 600 025
BONAFIDE CERTIFICATE
Certified that this project report “PLANNING ANALYSIS AND DESIGN OF
OVERHEAD CIRCULAR WATER TANK” is the bonafide work of following
students
RAMAIAH R M (720314103037)
RAMCHAND M T (720314103038)
SUBASH T (720314103051)
Who carried out the project work under my supervision.
SIGNATURE SIGNATURE
Mr.K.THIRUNAVUKKARASU, M.E.,
HEAD OF THE DEPARTMENT
ASSISTANT PROFESSOR
Mr.RATHNAVEL.PON,M.E.,
SUPERVISOR
ASSISTANT PROFESSOR
and Technology,
and Technology,
Kinathukadavu. Kinathukadavu.
Submitted for the project viva-voice examination held on ……………….
Internal Examiner External Examiner

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TABLE OF CONTENTS
CHAPTER NO TITLE PAGE
NO.
ACKNOWLEDGEMENT iv
ABSTRACT vi
LIST OF TABLES viii
LIST OF FIGURES x
LIST OF SYMBOLS AND ABBREVATION xii
1 INTRODUCTION
1.1 WATER TANK 2
1.2 PROPOSED SITE 5
1.3 SOURCES OS WATER SUPPLY 6
1.4 POPULATION FORECASTING 8
1.5 GENERAL DESIGN REQUIREMENTS 9
1.6 PROJET SCOPE 10
1.7 PROJECT OBJECTIVE 11
1.8 PROJECT COMPONENTS 11
1.9 PROJECT METHODOLOGY 12
2 PLANNING 13
2.1 PLAN
2.2 ELEVATION
3 ANANLYSIS 14
3.1 OUTLINE OF ANALYSIS 15
3.2 ANALYSIS SUMMARY 17
3.3 SELF WEIGHT 18

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3.4 LOADS ACTING REGION 19
3.5 COLUMN,BRACE,PLATE PROPERTIES 20
3.6 ANALYSIS RESULTS 21
4 DESIGN
4.1 DESIGN COMPONENTS 23
4.2 POPULATION FORECASTING 24
4.3 CIRCULAR TANK
4.3.1 DESIGN 25
4.3.2 DESIGN OF ROOF SLAB 26
4.3.3 DESIGN OF TANK WALL 29
4.3.4STRUCTURAL DRAWING 35
4.3 BEAM
4.3.1 DESIGN 36
4.3.2 STRUCTURAL DRAWING 42
4 .4 COLUMN
4.4.1 DESIGN 43
4.5 FOOTING
4.5.1 DESIGN 45
5 5.1 CONCLUSION 52
REFERENCE 53

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ACKNOWLEDGEMENT
The success of a work depends on the team and its cooperation. We take this
opportunity to express our gratitude and sincere thanks to everyone who helped us
in our project. First and foremost, we would like to thank the Management for the
Excellent Infrastructure, facilities and the constant support provided for the
successful completion of the project work.
We are indebted to the Director,
Dr.K.THANUSHKODI,M.Sc.,(Engg),Ph.D., for his continuous motivation,
inspiring words and guidance throughout this project.
We express our sincere thanks to the Joint Director Dr.N.SUGUNA,
M.E.,Ph.D., for her valuable guidance and support.
We wish to express my heartfelt thanks and deep sense of gratitude to the
Principal,Dr.J.JAYA, M.Tech.,Ph.D., for the continuous encouragement, guidance
and support.
Our special thanks to Mr.S.KAPILAN, M.E.,(Ph.D)., PRO, Civil
Engineering, for his valuable guidance, continuous support and suggestions to
improve the quality of the project work.
We thank our Assistant Professor Mr.K.THIRUNAVUKKARASU, M.E.,
Head of the Department, Department of Civil Engineering, for his valuable
guidance, continuous support and suggestions to improve the quality of the project
work.
We express our special thanks to our guide, Professor,
Mr.RATHNAVEL.PON,M.E for his valuable guidance, insightful comments and
continuous support to carry out the project work.
We express our deep sense of gratitude to all the Faculty members and
supporting staff for their continuous support in completing this project work
successfully.Our sincere thanks to our family members and friends for their support
and motivation to carry out this project successfully.

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ABSTRACT
In this project, we have planned, analyzed and designed an overhead circular
reinforced cement concrete tank, to cater to requirements of Seerapalayam village
panchayat. The population of the village panchayat is estimated as 1350 using
conventional population forecasting methods. For this requirement, a circular
overhead water tank is planned using the popular drafting software AutoCAD 2D. It
is further analyzed using the premiere analysis software STAADPRO. Based on the
analysis using STAAD PRO, the salient features of the overhead circular water tank
is manually designed. The design and detailed drawings are presented in this project
work.

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LIST OF TABLES
TABLE TITLE PAGE NO.
1 Water Demand 7
2 Population Forecasting 26

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LIST OF FIGURES
FIGURE TITLE PAGE NO.
1 Project Methodology 12
2 Cirucular Mesh Analysis 19
3 Self Weight 20
4 Load Acting Region 21
5 Column, Brace, Plate properties 22
6 Staad Pro Output Verification 23

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LIST OF SYMBOLS AND
ABBREVIATIONS

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LIST OF SYMBOLS
A - Area
Ast - Area of tensile steel reinforcement
Asc - Area of Compression steel
BM - Bending Moment
b - Breadth of the section
D - Overall Depth of beam (or) slab
𝐹𝑦 - Characteristic strength of steel
L - Effective length of slab along shorter span
𝑙 𝑥 - Effective length of slab along longer span
MR - Moment of resistance
M - Modular ratio
P - Axial load on a compression member
Sv - Spacing of stirrups
UDL - Uniformly distributed load
V - Shear force
Vs - Design Shear Force
W - Total load
Z - Lever arm

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αx - Bending moment co-efficient along shorter span
αy - Bending moment co-efficient along longer span
σ cbc - Permissible stress in concrete in bending compression
σst - Permissible stress in steel in tension
τv - Nominal shear stress
τc - Shear stress in concrete (permissible)
τcmax - Shear stress in concrete with shear reinforcement
ǿ - Diameter of bar
Ld - Development length
mm - Millimeter
N - Newton
C/C - Centre to centre distance
F e415 - High Yielding strength deformed bars
M 15, M20 - Grade of concrete
B.V - Basic Value
M.F - Modification Factor

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1.1 WATER TANK
A water tank is an elevated structure supporting a water reservoir
constructed at a height sufficient to pressurize a water supply system for the
distribution of potable water, and to provide emergency storage for fire
protection.Water tanks often operate in conjunction with underground or surface
service reservoirs, which store treated water close to where it will be used. Other
types of water towers may only store raw (non-potable) water for fire protection or
industrial purposes, and may not necessarily be connected to a public water supply.
Water tank are able to supply water even during power outages, because they
rely on hydrostatic pressure produced by elevation of water (due to gravity) to push
the water into domestic and industrial water distribution systems; however, they
cannot supply the water for a long time without power, because a pump is typically
required to refill the tower. A water tower also serves as a reservoir to help with
water needs during peak usage times. The water level in the tower typically falls
during the peak usage hours of the day, and then a pump fills it back up during the
night. This process also keeps the water from freezing in cold weather, since the
tower is constantly being drained and refilled.[citation needed]
Although the use of elevated water storage tanks has existed since ancient
times in various forms, the modern use of water towers for pressurized public water
systems developed during the mid-19th century, as steam-pumping became more
common, and better pipes that could handle higher pressures were developed. In
Great Britain, standpipes, literally consisted of tall, exposed, inverted u-shaped
pipes, used for pressure relief and to provide a fixed elevation for steam-driven
pumping engines which tended to produce a pulsing flow, while the pressurized
water distribution system required constant pressure. Standpipes also provided a

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convenient fixed location to measure flow rates. Designers typically enclosed the
riser pipes in decorative masonry or wooden structures. By the late 19th-Century,
standpipes grew to include storage tanks to meet the ever-increasing demands of
growing cities.
A variety of materials can be used to construct a typical water tower; steel and
or pre stress concrete are most often used (with wood, or brick also in use),
incorporating an interior coating to protect the water from any effects from the lining
material. The reservoir in the tower may be spherical, cylindrical, or an ellipsoid
with a minimum height of approximately 6 metres and a minimum of 4 m in
diameter A). standard water tower typically has a height of approximately 40 m
Pressurization occurs through the hydrostatic pressure of the elevation of water; or
every 10.20 centimetres of elevation, it produces 1 kilopascal of pressure. 30 m of
elevation produce roughly 300 kPa, which is enough pressure to operate and provide
for most domestic water pressure and distribution system requirements.
The height of the tower provides the pressure for the water supply system, and
it may be supplemented with a pump. The volume of the reservoir and diameter of
the piping provide and sustain flow rate. However, relying on a pump to provide
pressure is expensive; to keep up with varying demand, the pump would have to be
sized to meet peak demands. During periods of low demand, jockey pumps are used
to meet these lower water flow requirements. The water tower reduces the need for
electrical consumption of cycling pumps and thus the need for an expensive pump
control system, as this system would have to be sized sufficiently to give the same
pressure at high flow rates.
Very high volumes and flow rates are needed when fighting fires. With awater
tower present, pumps can be sized for average demand, not peak demand; the water

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tower can provide water pressure during the day and pumps will refill the water
tower when demands are lower.
1.1.1 TYPES OF OVERHEAD TANKS:
A water tank is used to store water to tide over the daily requirements. It is an
important structure in day today life as it fulfils the daily requirement of water to
public needs.
The water tanks can be classified under three heads:
1) Tanks resting on ground.
2) Elevated tanks supported on staging.
3) Underground tanks.
From the shape point of view, water tanks are classified as ,
1) Circular tanks.
2) Rectangular tanks
3) Spherical tanks
4) Intze tank
5) Circular tank with conical bottoms.
For our design, the most popular water tank in India, the circular overhead tank is
chosen
1.1.2 OVERHEAD CIRCULAR WATER TANK:
When water is filled in circular tank, the hydrostatic water pressure will try to
increase in diameter at any section. However, this increase in the diameter all long

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the height of the tank will depend on the nature of the joint at the junction of the wall
and bottom slab. If the joint is flexible, it will be free to move outward . the
hydrostatic pressure will be zero and hence there will be no change in diameter and
hydrostatic pressure at the bottom will be maximum, resulting in the maximum
increase in the diameter and maximum movement ,if joint is flexible.
When the joint between the wall and floor is rigid, no horizontal displacement
of the wall at the joint is possible. The deflected shape of the wall will be along
deflected. The upper part will have hoop tension, while the lower part will bend like
cantilever fixed at joint at the bottom. For shallow tanks with large diameter, hoop
stresses are very small and the wall acts more like cantilever. For deep tanks of small
diameter, the cantilever action due to fixed at the base will be small and the hoop
action will be predominant.
1.2 PROPOSED SITE:
The proposed site for our project is located at Seerapalayam Panchayat of
Coimbatore district. The latitude 10.878909 and longitude 76.973734 are the
geocoordinate of the Seerapalayam. Our site situated at the place where all the
natural conditions are suitable for the construction of elevated overhead water tank.
This location is one of the developing area, where there is steady increase in
Population in recent years. The population of the area according to recent survey is
around 1260. Thus this location requires a periodic water supply system atleast twice
a week. This location consist nearly 50% agricultural land. Around 450+ houses are
there and so it requires more than 100m3
capacity water tank. From the three major
types of water tank, we had adopted Elevated Overhead tank because the location
needs pressurized water supply. Other than Elevated Overhead tanks, other types of

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water tank are not suitable because they do not give pressurized water supply like
Elevated Overhead Tank.
1.3 SOURCES OF WATER SUPPLY :
The various sources of water can be classified into two categories:
Surface sources, such as
1. Ponds and lakes
2. Streams and rivers
3. Storage reservoirs
4. Oceans, generally not used for water supplies, at present.
Sub-surface sources or underground sources, such as
1. Springs
2. Infiltration wells
3. Wells and Tube-wells.
1.3.1 Water Quantity Estimation
The quantity of water required for municipal uses for which the water supply
scheme has to be designed requires following data:
Water consumption rate (Per Capita Demand in litres per day per head)
Population to be served.
Quantity= Per demand x Population
It is very difficult to precisely assess the quantity of water demanded by the

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public, since there are many variable factors affecting water consumption. The
various types of water demands, which a city may have, may be broken into
following class
TABLE 1. WATER DEMAND
The factors affecting water demand may be summarized as follows
• Size of the city
• Presence of industries.
• Climatic conditions.
• Habits of economic status.
• Quality of water:
• Pressure in the distribution system.
• Efficiency of water works administration:
• Cost of water.
• Policy of metering and charging method
Domestic purpose 135 litres/c/d
Industrial use 40 litres/c/d
Public use 25 litres/c/d
Fire demand 15 litres/c/d
Losses, Wastage and thefts 55 litres/c/d
Total 270 litres/c/d

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This quantity should be worked out with due provision for the estimated
Requirements of the future. The future period for which a provision is made
in the water supply scheme is known as the design period.
Design period is estimated based on the following:
• Useful life of the component , considering obsolescence, wear, tear, etc.
• Expandability aspect.
• Anticipated rate of growth of population, including industrial, commercial
developments & migration-immigration.
• Available resources.
• Performance of the system during initial period.
1.4 POPULATION FORECASTING METHODS
The various methods adopted for estimating future populations are given
below. The particular method to be adopted for a particular case or for a particular
city depends largely on the factors discussed in the methods, and the selection is
left to the discretion and intelligence of the designer.
1. Incremental Increase Method
2. Decreasing Rate of Growth Method
3. Simple Graphical Method
4. Comparative Graphical Method
5. Ratio Method

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6. Logistic Curve Method
7. Arithmetic Increase Method
8. Geometric Increase Method
In our design, the population is forecasted using Arithmetic, Geometric,
Incremental and Decreasing Rate methods and the average value is taken as design
population.
1.5 GENERAL DESIGN REQUIREMENTS (IS: 3370)
Plain concrete structures: Plain concrete members of reinforced concrete
liquid structures may be designed against structural failure by allowing tension in
plain concrete as per permissible limits for tension in bending specified in IS:456-
2000.
1.Permissible Stresses in Concrete:
(a) for resistance to cracking : the IS:456-2000 does not specify the
permissible stresses in concrete for its resistance to cracking. The permissible tensile
stresses due to bending apply to face of the member in contact with the liquid. In
members with the thickness less than 225mm and in contact with the liquid on one
side.
(b)For strength calculations: For strength calculations the usual permissible
stresses in accordance with IS:456-2000 are used. Where the calculated shear stress
in concrete above exceeds the permissible value, reinforcement acting in conjunction
with diagonal compression in concrete shall be provided to take whole of the shear.

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3.Permissible Stresses in Steel in Reinforcement:
When steel and concrete are assumed to act together for checking the tensile
stresses in concrete for avoidance of cracking the tensile stresses in steel will be
limited by the requirement that the permissible tensile stress in concrete is not
exceeded so that tensile stresses in steel shall be equal to product of modular ratio of
steel and concrete.
4.Steel reinforcement:
The minimum reinforcement in walls ,floor, and roofs in each of the two
directions at right angles shall have an area of 0.3% of the concrete section in that
direction for sections up to 100mm thickness. For sections of thickness greater than
100mm and less than 450 mm the minimum reinforcement in each of the two
directions shall be linearly be reduced from 0.3% for 100 mm thick section to 0.2%
for 450mm, the minimum reinforcement in each of the two directions shall be kept
at .2%.
5.Minimum cover to reinforcement:
For liquid faces of parts of members either in contact with the liquid or
enclosing the space above the liquid, the minimum cover to all reinforcement should
be 25mm or the diameter of main bar, whichever is greater.
1.6 PROJECT SCOPE
 To make a study about the analysis and design of water tank.
 To make a study about the guidelines for the design of liquid retaining
structures according to IS Code.
 To know about the design philosophy for the safe and economical
design of water tank.

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 To conduct case studies on the existing overhead water tank.
 To know about the problems faced by the people in water supply around
the areas of existing water tank.
 To find the possible solution and meet the daily requirements of water.
 To overcome the problem of low water pressure at all distribution ends.
 To choose a location around the area where water losses are minimum
and good efficiency is maintained.
 To increase the design life period and serviceability of the structure.
1.7 PROJECT OBJECTIVE
To plan, analysis and design a water tank (Overhead Water Tank – made of
Reinforced Cement Concrete) for Seerapalayam panchayat.
1.8 PROJECT COMPONENTS
* Functional Planning
- Selection of Site
- Estimation of Tank Capacity
- Design of Tank Dimensions
* Structural Analysis and Design
- Preparation of Tank Plan using AUTOCAD
- Analysis of the Structure using STAAD PRO
- Manual Design based on STAAD PRO Results

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1.9 PROJECT METHODOLOGY:
SQW
FIG 1. PROJECT METHODOLOGY
DRAWING
1.SITE LAYOUT
2.PLAN AND ELEVATION OF
CIRCULAR WATER TANK.
3.REINFORCEMENT DETAILS.
AUTO CAD
ANALYSIS
STAAD PRO 1. STRUCTURAL ANALYSIS OF
CIRCULAR WATER TANK..
DESIGN
LIMITE STATE
METHOD 1. DESIGN OF CIRCULAR TANK:
 DESIGN OF TANK WALL.
 DESIGN OF FLOOR SLAB.
 DESIGN OF BASE SLAB.
 DESIGN OF GRIT&BRACE BEAM.
 DESIGN OF COLUMN&FOOTING.

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3.1 OUTLINE OF ANALYSIS:
The analysis of the structure that is determination of the internal forces like
Bending moment, shear force, etc in the component members, for which these
members have to be designed, under the action of given external loads. This process
requires the knowledge of structural mechanics which includes mechanics of rigid
bodies (i.e. mechanics of forces), mechanics of deformable bodies (i.e. mechanics
of deformations) and theory of structures (i.e the science dealing with response of
structural system to external loads). A brief review is taken of structural analysis to
refresh the basic principles.
The framing of a multi storied building consist of columns, girders, and beams
which support roof and floor load. Such type of building frames is something called
beam and column frame. The beam with supports the external wall is known as wall
beam or spaniel beams. A building frame may consider a number of base and may
have several stories. A multi-storeyed, multi panelled frame is a complicated
statically indeterminate structure. It consist of number of beams and columns built
monolithically, framing a network. The doors and walls are supported on beams that
transmit the loads to the columns. A building frame is subjected to both vertical as
well as horizontal loads. The vertical load consists of dead weight of the structure
components such as beams, slabs, columns, etc., and live load. The horizontal load
consists of wind forces and earthquake forces. The ability of a multi-storied building
to resist the wind 7 other lateral forces depends upon the rigidity of the connection
between beam and columns. When connections of beam and columns are fully rigid,
the structure as a whole is capable of resisting lateral force acting on the structure.
The columns for multi-stored buildings can be fabricated for one, two or more storey.
Columns may be continuous through two or three storey and the beam on each
floor is connected to such continuous column on their sides. In order to achieve

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optimum utilization of column properties, the columns are arranged with flanges
parallel to the long axis of the structure, since the traverse wind condition is the most
severe.
Foundation, required to take the super-imposer loads on the columns, usually
consists of rafts, piles or piers going deeper, harder, strata. Structural behaviour of
multi-storied buildings subjected to lateral forces complex and. highly indeterminate
There are three recognized types of joints between beams and columns, simple, semi
rigid and rigid joints. Frames with flexible joints have no internal resistance against
horizontal loads. In another way it is possible to provide lateral resistance with the
introduction of vertical walls in proper locations. These are referred as diaphragms.
Such diaphragm infill should be made of some structural materials of substantial
stiffness and should be positively attached to the frame. The stiffness of infill
diaphragm will resist any change to the original rectangular shape of the frame.

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3.2. ANALYSIS SUMMARY
FIG 2. CIRCULAR MESH ANALYSIS

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3.3 SELF WEIGHT:
FIG 3. SELF WEIGHT

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3.4 LOAD ACTING REGION:
FIG 4. LOAD ACTING REGION

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3.5 COLUMN,BRACE,PLATE PROPERTIES:
FIG 5. COLUMN,BRACE,PLATE PROPERTIES

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3.6 ANALYSIS RESULTS:
FIG 6. STAAD PRO OUTPUT VERIFICATION

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4.1 DESIGN COMPONENTS:
By using IS standards the following components are designed,
1. Estimation of population
2. Design of circular water tank,
a. Design of tank wall.
b. Design of roof slab.
c. Design of base slab.
d. Design of beam.
e. Design of grit beam.
f. Design of column.
3. Design of footing,

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4.2. POPULATION FORECASTING IN SEERAPALAYAM VILLAGE
YEAR POPULATION INCREASE
PER
DECADE
INCREMENTAL
INCREASE
PERCENTAGE
INCREASE
DECREASE IN
PERCENTAGE
INCREASE
1960 536 ---- --- --- ---
1970 652 116 --- 21.6 ---
1980 721 69 -47 10.5 -11.1
1990 829 108 39 13.02 2.52
2000 950 121 13 14.59 1.57
2010 1124 171 50 18 3.41
AVERAGE 117 13.75 15.5 -3.6
TABLE 2. POPULATION FORECASTING
Arithmetical progression method
= 1124+117 = 1241
Geometrical progression method
= 1124 + (15.5/100) (1000) = 1279
Incremental increase method
= 1000 + 117 + 14 = 1255
Changing increase rate method
= 1124 + (18 + 3.6) (1000) / 100 = 1340
Considering highest value , P = 1340
Rounded off to Population of P = 1350

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4.3. CIRCULAR WATER TANK
4.3.1 DESIGN OF CIRCULAR WATER TANK:
PERMISSIBLE STRESS:
σcbc = 8.5 N/mm2
σcc = 6 N/mm2
σct = 1.3 N/mm2
[ for Tank wall ] and 3.2 N/mm2
σst = 150 N/mm2
DIMENSION OF TANK:
Capacity = 182250 litres (m3
)
Π x 4 x D2
/ 4 = 182.22
∴D =8m
Load Calculation:
Self weight of slab = 0.125 x 25 x 1 = 3.125 N/mm2
Self weight of beam = 0.3 x 25 x 0.65 = 2.65 N/mm2
Live load + floor finish load = 2.5 N/ mm2
Total load = 3.125 + 2.5
= 3.125 + 5.625 + 2.625
∴Total Load = 8.250
THICKNESS OF TANK WALL:
t = Thickness of tank wall , from cracking consideration.

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(ϒ x H x D /2)/ (1000t + (m-1) Ast) = σct
(10 x 4.2 x 8/2) / [ 1000 x t + 12 x1680] = 1.3
1) t = 109 mm ~ 110 mm
2) t = (30 x H ) + 50
= (30 x 4.2 )+50
t = 176 mm
4.3.2 DESIGN OF ROOF SLAB :
D = 8.176 M
Thickness of slab = 125MM
Self weight = 0.125 x 25 x1 = 3.125k N/m2
Live Load = 1 kN/m2
Total Load = 4.125 kN/m2
CENTER OF SLAB:
(Mx)c = (Mθ)c = 3/16 x wu
2
= 3/16 x 4.125 x (8.176/2)2
(Mx)c = 12.91kN/ m2
Circumferential Moment:
(Mθ)c =2/16 x wu
2
∴ (Mθ)c = 8.61kN/m2
d =
√12.91 𝑥 106
√1000 𝑥 1.32

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= 98.9 mm ~ 100mm
Provide total thickness of 176 mm using 12 mm dia bars with clear cover of 15
mm.
D = 176 – 15 – 6
= 155 mm
For 1st
Layer ,
155 – 12 = 143mm
Circumferential Reinforcement required @ center, Ast
=12.9x106
/143 x0.853 x 155
= 682.24~ 690 mm2
Provide 12 mm dia bars.
Spacing = ast/Ast x 1000
= 113 /690 x 1000
= 163.76 mmc/c
= 176 -15 – 2x12 – 6
= 131 mm
(Ast)θ = 8.61 x 106
/ 11.5 x 0.85 x 131
= 672 mm2
Spacing = 169 mm c/c
The Circumferential steel will be provided for a length = 2/3 x 45 x Φ

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= 2/3 x 45 x 12
=360 mm ~315 mm c/c
Hence provide 12mm dia bars at 200 mm c/c spacing.
Total Rings = 360/200
= 1.8 ~ 2
Pr = ½ x w x a
= ½ x4.125 x (8.176/2)
= (8.43 x 103
) / 1000 x 143
= 0.058 kN/ m2
< 2 N/mm2
Hence Safe

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4.3.3 DESIGN OF TANK WALLS:
The maximum ring tension occurs at depth 3m below the water surface ( table 5.15
Hoop tension)
Pr = 0.608(w x H x d/2) at 0.6 x H from top
Pr = (0.608 x 10 x 4.2 x 8/2)
Pr = 102.14 kN
Acting at 2.52 meters from top
Ast = 102.14 x 103/
115
= 888mm2
Provide 12mm dia rods
Spacing:
Spacing = (113.09 / 888) x 1000
= 127 mm c/c
Both sides = 254
Provide rings 250 mm spacing as provided.
Tensile Stress in concrete wall
= [102.14 x 103
/ 1000 x 210 + 12 x 888 ] < 1.2
= 0.48 N/mm2
<1.2 N/mm2
Hence Safe
Bending Moment = 3155.6 N m

49
d =
√3155.6 𝑥 103
√1000 𝑥 1.5
d = 45.86 mm ~50 mm
Provide minimum thickness = (3H + 5)
= (3 x 4 + 5)
= 12 +4 = 16cm
Using 12mm dia bars and clear cover as 25 mm,
Available d = 160 – 31
= 109 mm
Actual BM = 3155.6 x 103
/ 115 x 0.853 x 109
= 295.12 mm2
~ 295 mm2
= Provide 10 mm dia bars
Spacing =ast/ Astx 1000
= 78.53 / 295 x 1000
= 270 mm c/c
∴Provide 10 mm dia bars @ 270 mm c/c spacing.
Development length ,Ld =
= (10 x 115 ) / (4 x 0.8)
= 360 mm = 0.36m
400mm c/c spacing clear cover 25 mm. Distribution reinforcement of 0.3 %
Ast = (0.3 /100) x 160 x 1000

50
= 480 mm2
Area of steel on each face = 240 mm2
No additional reinforcement will be provided at the inner face, since the Vertical
steel for cantilever
Provide 8 mm dia bars
∴ Spacing =ast/ Ast x1000
= 50.25 / 480
= 210 mm
∴ Provide Distribution reinforcement of 8 mm dia bars @ 210 mm c/c spacing.
Development length ,Ld =
= (10 x 115 ) / (4 x 0.8)
= 360 mm
= 0.36m
400mm c/c spacing clear cover 25 mm. Distribution reinforcement of 0.3 %
Ast = (0.3 /100) x 160 x 1000
= 480 mm2
Area of steel on each face = 240 mm2
No additional reinforcement will be provided at the inner face, since the Vertical
steel for cantilever
Provide 8 mm dia bars

51
∴ Spacing =ast/ Ast x1000
= 50.25 / 480 = 210 mm
∴ Provide Distribution reinforcement of 8 mm dia bars @ 210 mm c/c spacing.
BASE SLAB:
Slab thickness = 210 mm
Weight of water = 3 x 1 x 1 x 9.8 = 23.4 kN / m2
Self weight of slab = 0.21 x 1 x 25 = 5.25 kN / m2
Weight of roof slab = 0.125 x 1 x 25 = 3.125 kN / m2
Weight of tank wall = 0.125 x 1 x 25 = 3.125
P = 35 kN / m2
Circumferential Moment = (Mo)c
= (1/16) x P x a2
= (1/16) x 35 x (8.125/2)2
= 36.10 kN m
∴Radial moment = 36.10 kN m
Radial shear = (1/2) x P x a
= ½ x 35.6 x (8.125 / 2)
= 72.31 kN.m
(Mr)c = (2/16) x P x a2
= (2/16) x 35 x (8.125/2)2

52
= 58.72 kN m
Radial Moment is zero at radius given by ,
Mr = 0
= (1/16) x P x (a2
– 3r2
)
r = a / 2√3
= 8.125 / 2√3
∴r = 2.34 m
Point of Contra flexure = 1.08m
d =
√68.72 𝑥 106
√1000 𝑥 1.32
d = 227 mm
Using 25mm clear cover
Effective Depth = 227 +25 + 12.5
= 264.5 mm
Say 270 mm
= 270 – 25 – 12.5 = 232.5 mm
Spacing:
Ast = (58.72 x 106
) / ( 115 x 0.853 x 232.5)
∴Ast = 2574 mm2
Provide 25 mm dia rods
Spacing =ast / Ast x 1000

53
= 490 / 2574 x 1000 = 190 mm
∴ Provide 25 mm dia radial bars @ 190 mm c/c from edge to the distance 1.08
m.
Provide 2 rings of 25 mm dia wires to support these.
CHECK FOR SHEAR:
Pr = 58.72
𝛕V = Pr/ b x d
= 58.72 x 103
/ 1000 x 232.5
= 0.256
=100 Ast / b x d
= 100 x 2574 / 1000 x 232.5
= 1.15
𝛕c = 0.64 -------
𝛕v<𝛕c
Hence it is safe for shear section

55
4.3.4 DESIGN OF BEAM:
Square beam
Size = 300x300
Self weight of slab = 3.125KN
Self weight of beam = 2.625KN
Floor finish +live load =2.5KN
W = 8.25KN/M
DESIGN
Effective depth
d =300-50 =250mm
LOAD CALCULATION:
Load on beam =8.25KN/M
Dead load = 25x0.3x0.3 =2.25KN/M
Total load =8.25+2.25 =10.5KN/M
Design load =10.5x1.5 =15.75KN/M
MOMENT CALCULATION:
Mu =WL2
/8
= 15.75X32
/8
= 17.17KNM

56
Mub =0.138fckbd2
=0.138x20x300x3002
Mu = 74.52x106
KN
REINFORCEMENT DETAILS:
Mub =0.87 fyAST d (1-(415AST/fck bd)
74.52x106
=0.87x415Xastx300(1-415AST/20X300X250)
74.52X106
=90.26X103
AST-24.97AST2
AST = 1276.14mm2
Assume 25mm dia bar
No of bars =AST/ast
= 1276.14/384.65
=3.32 say 4nos
Provide 4 nos 25mm dia
SHEAR REINFORCEMRNT:
Vu = WL2
/2
= 15.75X3/2
=23.55KN
𝛕V = Vu/bd
= 23.55x103
/300x250

57
=0.314N/mm2
Pt =100AST/bd
=100x1276.14/300x250
=1.70%
From the table 19, IS 456-2000
𝛕c =0.72N/mm
Hence 𝛕c < 𝛕V
The section is safe in shear yet minimum shear reinforcement is provided for beam
S𝑆 𝑢 = 0.87 fyAsv/0.4 b
= 0.87x415x2x50.3/0.4x300
= 302mm say 300mm
Provide stirrups 8mm @ 300mm spacing c/c
DESIGN OF GRID BEAM :
Size = 300x650
Self weight of (roof + floor) slab = 5.25 KN
Weight of tank wall = 2.625KN
Floor finish +live load = 2.5 KN
W = 8.25KN/M
DESIGN
Effective depth

58
D = 600mm
LOAD CALCULATION
Load on beam =8.25KN/M
Dead load = 25x0.3x0.65 =2.25KN/M
Total load =8.25+2.25 =10.5KN/M
Design load =10.5x1.5 =15.75KN/M
MOMENT CALCULATION
Mu =WL2
/8
= 15.75X32
/8
= 17.17 kN m
Mub =0.138fckbd2
=0.138x20x300x6002
MU = 298.08x106
kN m
REINFORCEMENT DETAILS:
Mub =0.87 fyAst d (1-(415Ast/fck bd)
74.52x106
=0.87x415x astx300(1-415Ast/20 x300x600)
74.52X106
=90.26X103
Ast -24.97Ast
2
Ast = 1715.0 mm2
Assume 25mm dia bars

59
Spacing =ast/Ast X1000
490.87 / 1715.0 x1000 =286.22mm
Say 285 mm spacing
No of bars = Ast/ast
= 1715 /285 =6.01 nos
Provide 7nos 25mm dia
SHEAR REINFORCEMRNT:
Vu = WL/2
= (15.75x3) /2
=23.55KN
𝛕V = Vu/bd
= 23.55x103
/300x600
=0.13 N/mm2
Pt =100Ast/bd
=100x1715/300x600
= 0.95 %
From the Table 19, IS 456-2000
𝛕c =0.8 N/mm2
Hence 𝛕c < 𝛕V
The section is safe in shear yet minimum shear reinforcement is provided for beam

60
Su = 0.87 fyx Asv/0.4 b
= 0.87x415x2x50.3/0.4x300
= 302mm say 300mm
Provide stirrups 8mm @ 300mm spacing c/c

62
4.3.5 COLUMN:
Size = 300 x 300
(since the total load on column is p =96.56 kN ,we design the column for the max.
load of 1000kN for more obtaining more serviceability)
Axial load = 1000 KN
SBC of soil = 200 KN/m2
Material = M20 & Fe415
MAIN COLIUMN REINFORCEMENT:
Factored load on column ,Pu = (1.5 x 1000)
= 1500 KN
P = 0.4fckAc + 0.67fyAsc
= 0.4fck(Ag-Asc) + 0.67fyAsc
Ag = 300 x 300
= 90000 Nm2
1x103
= 0.4 x 20 (9x104
- Asc) + 0.67 x AIS x Asc
= 720 x 103
-8Asc + 278.05Asc
1 x 103
= 720 x103
+ 270.05 Asc
780 x 103
= 270.05Asc

63
Asc = 780 x 103
/270.05
= 2888.33 mm2
Ac = Ag – Asc
= 9000 – 2888.33
= 87.11 x 103
Min. reinforcement = 0.8% of gross Area
Asc =720 mm2
Provide 4 bars of 22mm dia. With
Asc = 1520 mm2
Lateral ties:
Greater diameters of,
i. 224 = 5.5 mm
ii. 5 mm
Adopt 6mm dia. Ties
Pitch of ties is the least of
i. Least lateral dimensions = 300 mm
ii. 16 times of longitudinal bar = 16 x 22 = 352 mm
iii. 300 mm
Adopt 6mm ties @ 250 mm C/C.

65
4.3.6 FOOTING:
(since the load axial load on the footing is 96.56 kN we choose the max. load of
1000 kN for the obtaining more serviceability)
Load on column = 1000x 1.5 = 1500 KN
Self weight of footing (10% ) = 150 KN
Total ultimate, Wu = 1650 KN
Footing area = (1650/1.5 x 200)
= 5.5 m
Hence , (3X x 5X) = 5.5
X = 0.604m
Short side of footing = (3 x 0.604) = 1.814 m
Long side of footing = (5 x 0.604) = 3.02 m
Adopt isolated sloped footing.
Upward soil pressure at service load,
= (1000/2 x 3)
= 167 KN/m3
< 200 KN/m3
Hence it is safe.
Factored soil pressure, Pu = (1.5 x 167)
= 250.5 KN/m2
= 0.2505 N/mm2

66
Factored moments:
Cantilever projection from the short side face of the column’
= 0.5 (3- 0.5)
= 1.25m
Cantilever projection from the long side face of the column,
= 0.5 (2-0.5)
= 0.85 m
BM at the short side face of the column is,
= (0.5PuL2
)
= (0.5 x 250.5 x 1.252
)
BM at the long side face of column is,
= (0.5PuL2
)
= (0.5 x 250.5 x 0.852
)
= 90.5 KNm
DEPTH OF FOOTING:
From moment consideration,
Mu = 0.138fckba2
D = √
𝑀𝑢
(0.138𝑓𝑐𝑘𝑏)
= √
195.7 𝑥 106
(0.138 𝑥 20 𝑥 103

67
= 266.3 mm
From shear,
The critical section for one way shear is located at a distance from the face of the
column.
Shear force per meter width,
Vu = 0.2505 x 103
(1250 – d)
Assuming shear strength of concrete,
Te = 0.36 N/mm2
M20 grade concrete
P1 = 0.25
Tc = (Vu/ bd)
0.36 = {(0.2505 x 103
(1250 – d)/103
x d}
D = 513 mm
Hence adopt effective depth, d = 550 mm
Overall depth, D = 600 mm
Footing reinforcement:
(From IS 456-2000 CLAUSE 9.1.1)
Longer direction ,
Mu = 0.87fyAstd[1-Astfy/bdfck]

68
195.7 x 106
= 0.87Ast x 415 x 550 [1-415Ast/103
x 550 x 20]
Ast = 1029 mm2
Use 16mm dia. Bars at 160mm c/c,
Ast = 1257mm2
Shorter direction:
(90.5 x 106
) = 0.87Ast x 415 x 550 [1-415 Ast/103
x 550 x 20]
Ast = 468mm2
Ratio of long to short side = B
= (3/2)
= 1.5
Reinforcement in central band width of 2m,
= [2/B+1] Ast
= [2/1.5+1](2 x 468)
= 749mm
Hence provided 12mm dia. Bar at 150mm C/C,
Ast = 754mm2
CHECK FOR SHEAR STRESS:
One way shear:
The critical section for one way shear is located at distance ‘d’ from the face of the
column,

69
Factored shear force per meter width,
Vu = 250.5 x 0.7
= 176 KN
(100ast/bd) = (100 x 1257/1000 x 550)
= 0.228
Permissible shear stress = (Ks Tc)
= (1 x 0.33)
= 0.33 N/mm2
Nominal shear stress ,Tu = (Vu/ba)
= (176 x 103
/1000 x 550)
= 0.32 N/mm2
Two way shear:
The critical section for two-way shear is located at a distance of 0.5d from the face
of column,
Shear force on critical section,
Vu = [(3 x 2) – (1.05 x 0.85)]250.5
= 1280 KN
Periphery of the critical section,
Bo = 2(1.05+0.85)
= 3.8m

70
Tu = [Vu/bd]
= (1280 x 1000/3.8 x 1000 x 550)
= 0.612 N/mm2
The Permissible shear stress
= Ks Tc
Ks = (0.5+Pc) but > 1 and Tc = 0.16fck
Pc = (0.3/0.5)
= 0.6
Ks = (0.5 + 0.6)
= 1.1
Limited = 1
Tc = 0.6√20
= 0.715 N/mm2
Ks x Tc = (1 x 0.175)
= 0.715 N/mm2
“Ks Tc>Tc”
Hence safe.

71
5.1 CONCLUSION
The objective of the project was to design a circular overhead tank for a village
panchayat and the same was achieved as listed as follows
Seerapalayam Village Panchayat was chosen as the location and population
was estimated for the panchayat. Based on the estimated population and prevailing
water demand, the quantity of water to be supplied and stored in the tank was
computed.
The plan and other drawings for the circular overhead water tank was prepared
using AutoCAD 2D software
The analysis was done using STAAD PRO software and the structure was
analyzed for self-weight, meshes for surface loads, brace properties, etc and the
outputs were verified. The design data were acquired after due analysis.
After analysis, the design data were generated. Based on the design data, the
overhead circular tank was designed manually.
The design would satisfy the safety and economy norms and can be used for
any village panchayat with similar population.

72
REFRENCES
TEXT BOOKS
Dayaratnam P. Design of Reinforced Concrete Structures. New Delhi. Oxford &
IBH publication.2000
Sayal & Goel .Reinforced Concrete Structures. New Delhi. S.Chand
publication.2004.
CODE BOOKS
IS 456-2000 CODE FOR PLAIN AND REINFORCED CONCRETE
IS 3370-1965 CODE FOR CONCRETE STRUCTURES FOR STORAGE OF
LIQUIDS
IS 11682 – 1985 CODE FOR RCC STAGING OF STRUCTURES

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