Study of Structural Behaviour of Intze Water Tank through an user Friendly Program Developed by Visual Basic and by Sap

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 04 Issue: 08 | Aug -2017 www.irjet.net p-ISSN: 2395-0072
© 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 143
STUDY OF STRUCTURAL BEHAVIOUR OF INTZE WATER TANK
THROUGH AN USER FRIENDLY PROGRAM DEVELOPED BY VISUAL
BASIC AND BY SAP
Manohar B1, Kashinath B Rugi2
1PG student, Dept. of Civil Engineering, Government Engineering College, Haveri, Karnataka, India
2Asst.Prof. Dept. of Civil Engineering, Government Engineering College, Haveri, Karnataka, India
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Abstract – This project presents a critical review of the
current practice in the design of Overhead Intze water tank.
0The design is based on IS: 3370-1965 design code for water
retaining structures. The program is written by employing
powerful window complaint Visual Basic 6.0 programming
language. User friendly program is developed for thedesign of
water tank which will have provision for the user to choose
tank capacity, grade of concrete and steel, unit weight of
material etc. The tank is designed to resist stresses as per IS:
3370(Part II) - 1965, seismic design as per IS: 1893-2002. The
program will provide default values like height of staging,
bracing interval, diameter of cylindrical tank etc. Due to fluid
structure interactions, the seismic behaviourofelevatedtanks
has characteristics of complex phenomena. The main aim of
the study is to understand the behaviour of the supporting
system with SAP software. Here two different supporting
system with such as radial bracing and cross bracing are
compared with basic supporting system for various fluid
conditions and for differentcapacity. Tankresponsesincluding
base shear, overturning moment, bending moment at bottom
of column and story displacement has beenobserved, andthen
the results have been compared.
Key Words: Intze water tank, visual basic, Simple
bracing, Radial bracing, cross bracing, Base shear,
bending moment, displacement.
1. INTRODUCTION
The water tower will be essential structure supporting
of a water tank constructed at an elevation suitable to drive
of a water source system for a supply of potablewaterandto
provide an emergency storage of fire protection. The word
standpipe is used for exchangeable and it refers to a water
tower, one with tall and another with narrow proportions
especially in some places.
1.1 INTZE TANK
The Intze guideline is a German word: Intze– Prinzip, these
name provided to build different standards named after
water powered engineer “Otto Intze (1843-1904)”, in one
case the Intze standard identifieswatertowerandothercase
is requesting dam. The basic preference for this kind of tank
is the inward radial thrust of the conical base to balance an
outward radial thrust of the spherical lowest components.
This can be discovered to store considerable amount of
water for a raised spherical tank to provide flat floor slab
expectations work out to a uneconomical configuration.The
main principle of these floor slab turns into excessivelythick
to more tanks of diameter, it suits to best for Intze tank
under this condition. An Intze tank basically made of top
dome (roof), floor slab and the cylindrical shapedwall which
may be a consolidation for base spherical dome and conical
dome. Subjected to regulate compression, the thickness of
conical floor slab considerably meet expectations and a
chance to prove another economical flat slab floor.
The proportions of base dome and conical dome are
arranged to outward thrust with bottom domed and floor
only balances the internal thrust because of conical dome.
The diameter of lowest components of dome is preferably
about 65 to 70% of the diameter of the tank. Incline of
conical dome is in between 50 to 55 degree level according
to consideration. The tank needs to support one staging that
comprises an amount of columns to be spaced uniformly
along the perimeter of base ring beam through these
columns.
Fig-1 Different components of Intze tank.

1.2 Design procedure of Intze tank
 Outline for top dome and top ring beam.
 Design of cylindrical wall.
 Design of ring beam at the intersection of cylindrical
shaped wall to conical dome.
 Design of conical dome and bottom spherical dome,
 Design of bottom ring beam.
 About staging i.e. the design of supporting structure,
 About foundation design.
It is discovered that for storage of more capacity of water an
elevated circular tank provide floor slab works out to an
uneconomical design. It is mainly on account of the fact that
the floor slab becomes too thick for large diameters tanks.
Intze tank is best suitable under such circumstances. An
Intze tank essentially consist of a top dome (roof), the
cylindrical wall and the floor slab, which is a combination of
conical dome and bottom spherical dome.Beingsubjectedto
direct compression the thickness of the domical floor,works
out to be much less and hence it proves to be economical
alternative to flat slab floor. The proportion of the conical
dome and the bottom dome are so arranged that the
outward thrust from the bottom domed part of the floor
balances the inward thrust due to the conical domed part of
the floor. The diameter of the bottom dome should
preferably be about 65 to 70% of the diameter of the tank.
From considerations of economy, the inclination of the
conical dome should be between 50 to 55° with the
horizontal.
1.3 INTRODUCTION TO VISUAL BASIC
Fundamental VISUAL is a large amount of modifying
programming language starting with the advanced earlier
version of DOS form known as BASIC. BASIC means
Beginners universally symbolic typical direction book code.
It may be a generally not to take difficult modifying
programming language. The code takes a look to
considerable measure in English programming language.
Various software organizationshasbeenchangedthetypical
forms for BASIC such as Microsoft’s QBASIC, QUICKBASIC,
GWBASIC, IBM BASIC and so on. However, today individuals
want to utilize fundamentals of Microsoft Visual Basic,
similarly as it may be a great form of modifying
programming language to support resources to help all
around. Now, there exists plenty of VB forms exists in the
market. The most prominent majority is still utilizes various
VB programmers none other than VISUAL BASIC6.Similarly
likewise we need VB.NET, Visual Fundamental 2005, Visual
Basic 2008 and the recent version is Visual Basic 2010. Both
VB 2008 and VB 2010 are fully turned into object oriented
programming language.
1.4 Need for the present study
 The water tanks are visually simple but the analysisand
design are difficult.
 Generally there are shell type structures. These
structure’s methods are involved in complicated
analysis and design.
 The membrane theory is employed for design of the
elements of water tank. The membrane action will be
occur in joints with the ring beams this may cause in
local bending and this condition is more rigorous,which
necessitates in the elaborate analysis, detail and design.
An elevated water tanks involves considerable amount
of water mass at the top a slender staging which are
most critical respect for disappointmentoftank through
seismic activity.
 The conventional design for liquid tank is mostly based
on loading conditions; loading will be axi-symmetric
load by wind and seismic loads. Most of the designs are
based on it, it is more complicated to do hand
computations.
2. OBJECTIVES
 The main objective of the system is to develop a
user friendly computer program for the design of
water tank using Visual basic and SAP 2000. This
system will have the provision to choose namely
Tank capacity, Grade of concrete and steel, bearing
capacity of soil, Unit weight of the material etc.
 The tank dimensions obtained using Visual Basic
Programming are taken in SAP and the model is
analyzed for 3 different capacities like 500m3,
1000m3 and 1500m3 each capacity comprises of
different loading cases.
 Comparison of results for different models in terms
of base shear, displacement, overturning moment.
3. DESCRIPTION OF THE MODEL
For consideration purpose, 3d Intze RCC overheadtank with
typical capacities is taken. This design is taken for every
analysis methods to join with Indian Standard Codes for
practice. The water tank dome can be planned by working
stress method, supporting columnsandbracesvia limitstate
method

Table-1 Details of the specimen used for study of
structural behavior of Intze water tank.
3.1 Loads considered
Dead load (Floor finish) 1.0 kN/m2.
Imposed load 1.5 kN/m2
Zone factor (Z) 0.36 (Zone-5)
Importance factor (I) 1.0
Response reduction factor 5
Wind speed 33 m/s
Terrain category 2
Structural class B
Risk coefficient 1
3.2 Load combinations
In addition load combinations are illustrated in IS 875-
1987(Part 5- Special loads and combinations) with title as
“Code about act to design loads with buildings and
structures”. Here, the factors are need to consider are,
 1.5 (DL + IL)
 (DL +IL ± WL or EL)
 1.5 (DL ± WL or EL)
Fig-2 Screen shot showing dimensions of the Intze
Water Tank in VISUAL Basic
Fig-3 Intze water tank model with Radial bracing in
SAP
GEOMETRY OF THE TANK AS PER VISUAL BASIC PROGRAM
Capacity of the Tank 500mᶟ 1000mᶟ 1500mᶟ
Unit Weight of Concrete 25kN/mᶟ 25kN/mᶟ 25kN/mᶟ
Thickness of Top Dome 0.1m 0.1m 0.1m
Rise of Top Dome 2m 2m 2m
Size of Top ring Beam 0.2m*0.2m
0.25m*0.52
m
0.25m*0.25
m
Diameter of Tank 10m 12m 16m
Height of Cylindrical
wall
6m 8m 10m
Thickness of Cylindrical
wall
0.25m 0.3m 0.4m
Rise of Conical Dome 2m 2.4m 3.2m
Thickness of Conical
shell
0.2m 0.25m 0.3m
Rise of Bottom dome 1.25m 1.5m 2m
Thickness of Bottom
dome shell
0.3m 0.4m 0.5m
Number of Columns 8 10 12
Number of Bracing level 3 3 4
Size of Bottom ring
Beam
0.3m*0.2m 0.4m*0.6m 0.4m*0.6m
Distance between
Intermediate bracing
3m 5m 4m
Height of staging above
Foundation
12m 16m 20m
Diameter of Columns 0.5m 0.7m 0.8m
Size of Bracing 0.35m*0.35m
0.45m*0.45
m
0.5m*0.5m

Fig-4 Intze water tank model with cross bracing in SAP
3.3 Analysis methods
The static analysis has been done on all the models
considered. Both the methods are discussed in the below
section.
3.3.1 Static Analysis
The design lateral force is first computed for the
structure as a whole. This design lateral force shall then be
distributed to various floor levels.Theoverall designseismic
force thus obtained at each floor levels shall then be
distributed to various lateral load resisting elements. The
design base shear can be estimated as per IS 1893 (part ɪ):
2002, clause 7.5.3, The design horizontal seismic coefficient
for a structure shall be determined as per IS 1893 (part ɪ):
2002, clause 6.4.2, The fundamental natural period of
vibration considering without brick infill panels and with
brick infill panels for a moment-resisting frame building is
estimated as per the clause 7.6.1 and 7.6.2 of IS 1893 (part
ɪ):2002. The horizontal design lateral force is then
distributed to various lateral load resisting elements in the
building as per the clause 7.7.1 of IS 1893 (part ɪ):2002.
4. RESULTS AND DISCUSSIONS
A Results for various tank capacities.
4.1 Base shear
chart 1 Base shear for simple bracing.
Chart 2 Base shear for cross bracing.
Chart 3 Base shear for Radial bracing.
From the charts 1 to 3 along both X and Y direction it can be
observed that for 5 lac capacity in zone 4 and 5 region there
will be increase in 10% of base shear with change in bracing
systems from simple to cross bracing system similarly 20%
increase in base shear from simple to radial bracing system.
For 9 lac capacity in zone 4 and zone 5 regions increase in
9% of base shear can be seen with changeinbracingsystems
from simple to cross bracing system similarly 21% increase
in base shear from simple to radial bracing system .For 15
lac capacity in zone 4 and zone 5 regions base shear
increases by 3% for change in bracing systems from simple
to cross bracing system and 6% increase in base shear from
simple to radial bracing system can be observed. Due to
change in the zone i.e. from zone 4 to zone 5 it observed that
there will be 33% increase in base shear value for 5 lack
capacity 33% for 15 lac capacity.
4.2Displacement
Chart-4Displacement for simple bracing in EQ zone 5.

Chart-5 Displacement for cross bracing in EQ zone 5.
Chart-6 Displacement for radial bracing in EQ zone 5.
From chart-4 it is seen that for simple bracing displacement
decreased by 40% and 35% for 15 Lac capacity and 5 lac
capacity respectively when compared to displacement of 10
lac capacity tank. From chart-5 it is seen that for cross
bracing displacement decreased by 42% and 37%for15Lac
capacity and 5 lac capacity respectively when compared to
displacement of 10 lac capacity tank. From chart-6 it can be
seen that for radial bracing displacement decreased by 46%
and 38% for 15 Lac capacity and 5 lac capacity respectively
when compared to displacement of 10 lac capacity tank.
From above charts it is clear that the displacement is
minimum for radial bracing system when compared to
simple bracing and cross bracing.
B. Results for varying fluid level condition
4.3 Base shear
Chart 7 Base shear for different types of bracings in
Tank Empty, Half Full and Full condition
From Chart7 it is seen that for there is an increase in base
shear of 10% for Simple bracing to Cross bracing in empty
half full and full condition. Similarly the base shear is
increased by 13% for Simple bracing to Radial bracing in
empty, half full and full condition
4.4 Maximum bending moment
Chart 9 Maximum bending moment for different
types of bracings in Tank Empty, Half Full and Full
condition.
From the Chart- 9 it is observed that the maximum bending
moment is increased by 5% for simple bracing to Cross
bracing in Empty, Half Full and Full condition. Maximum
bending moment is increased by 2% for Simple bracing to
Radial bracing in Empty, Half full and full condition.
4.5 Maximum Displacement
From the Chart-10 it can be seen that there is a decrease in
Maximum story displacement of 1.83% forsimple bracing to
Cross bracing in Empty, Half full and full condition.Similarly,
there is a decreaseofmaximumstoreydisplacement by3.3%
for Simple bracing to Radial bracing in Empty, Half Full and
Full condition.

5. CONCLUSIONS
 Overhead water tank design includes formulae for
mathematical calculation and consumed time
duration, which resultsthecomputerprogramgives
a correct answer over the issues. This program is
developed by using Visual Basic which acts like a
preliminary design for the modeling of water tank
using software’s like SAP, STAD PRO etc. If the trial
and error method is adopted then it is somewhat
tedious to handle an economic section.
 With the increase in capacity of water tank and
staging height, base shear increases by 60% for
simple bracing, 56% for cross bracing and 50% for
radial bracing. Change in zone also increases the
base shear by 33% for different capacities, which is
consistent with the codal specifications.
 With the change in bracing pattern, base shear and
over turning moment varies and is found to be
increased by 10% for simple tocrossbracingandby
13% for simple to radial bracing.
 The Simple bracing (simple bracing) is effective in
reducing the bending moment by 2% compared to
radial bracing and by 5% comparedtocrossbracing
at the base of the column.
 Story displacements get reduced with the inclusion
of bracings. However, the radial bracings are found
to be effective in reducing the story displacement.It
is of the order of 4% of simple bracing and by 2% of
cross bracing.
REFERENCES
1. George W. Housner (1963) “The dynamic behaviour of
water tanks” Bulletin of the Seismological Society of
America. Vol.53, No. 2, pp. 381-387.
2. Sajjad Sameer U and Sudhir K. Jain (1994) “Lateral-Load
Analysis of Frame Staging’s for Elevated Water Tanks”
American Society of Civil Engineers, Journal of Structural
Eng. 120, pp.1375-1394.
3. S. C. Dutta, S. K. Jain, C. V. R. Murty (2000) “Assessing The
Seismic Torsional Vulnerability Of Elevated Tanks With Rc
Frame-Type Staging” Soil Dynamics And Earthquake
Engineering 19, pp. 183–197.
4. S. C. Dutta, S. K. Jain, C.V.R. Murty (2001) “Inelastic Seismic
Torsional BehaviourofElevatedTanks” Journal ofSound and
Vibration 242(1), pp. 151-167.
5. M.K.Shrimali and R.S.Jangid(2003)“TheSeismic Response
Of elevated Liquid Storage Tanks Isolated By Lead Rubber
Bearings” Bulletin of the NewzealandSocietyforEarthquake
Engineering, Vol. 36, No.3.
6. Sudhir K Jain and O. R. Jaiswal (2005) “Modifiedproposed
provisions for aseismic design of liquid storage tanks”
Journal of Structural Engineering No. 32-18 Vol.32,No.3, pp.
195–206.
7. R. Livaoglu and A. Dogangun (2005)“Seismicevaluation of
fluid-elevated tank-foundation/soil systems in frequency
domain” Structural EngineeringandMechanics,Vol.21,No.1
BIOGRAPHY:
Manohar B pursuing his
M.Tech. in Civil Strutures from
government Engineering
College, Haveri & obtained B.E.
Civil from R R I T
chikkabanavar Bangalore..
Kashinath B Rugi presently
working as Assistant Professor
in Government Engineering
College, Haveri. He has
obtained his, M.Tech from
NITK Suratkal & obtained B.E.
Civil from S I T College of
Engineering and Technology,
Tumkur.

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Study of Structural Behaviour of Intze Water Tank through an user Friendly Program Developed by Visual Basic and by Sap