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DOI: 10.23883/IJRTER.2017.3525.4Q54J 1
SEISMIC BEHAVIOUR OF ELEVATED RC CIRCULAR
WATER TANK OF DIFFERENT SHAFT
HEIGHTS
Kinjarapu Lakshmu Naidu1, Surapu Ramlal2 1,2Department of Civil Engineering, Aditya Institute of Technology and Management
Abstract— Water tanks are important public utility and industrial structures. Elevated water tanks
should be competent of keeping the expected performance during and after earthquake. During
the earthquake in India, R.C.C elevated water tanks are heavily damaged. This might be due to
improper geometrical selection of staging in many cases. The main aim of this study is to
understand the seismic behaviour of elevated RC circular water tank by considering five
different shaft staging heights with consideration of impulsive and convective water masses
inside the container. The analysis is carried out as per one mass model and two mass model by
considering four seismic Zones from Zone –II to Zone –V. In this study hydrodynamic forces and
sloshing wave heights are analysed for all the five different shaft staging heights.
Keywords— Base shear, Base moment, Hydrodynamic pressure, Impulsive mass, Convective mass,
Sloshing wave height.
I. INTRODUCTION
Exports are activities of selling goods to other countries. Indonesia’s main export capital is natural
wealth. From natural wealth owned, can be produced various kinds of export goods. Goods that can
be exported are goods that are in demand and needed by overseas buyers. Indonesian export
commodities consist of petroleum and gas (oil and gas) as well as non-oil and gas. Indonesia is one of
oil and gas exporter to destination country. Some of the countries that are export destinations of
Indonesia include the United States, Germany, Japan, China, Taiwan, and Australia. The country that
the main export destination of Indonesia is the United States. This study aims to analyze the value of
Indonesia’s oil and gas exports by using computer science. One of the analysis process that can be
done is forecasting the value of oil and gas exports in indonesia.
1.1 FAILURES OBSERED IN SHAFT STAGING WATER TANKS
The cylindrical shaft-type staging developed circumferential flexural tension cracks near the
base. Similar damages to support structures had been observed in past earthquakes and recently in
the Bhuj earthquake of 26th January 2001, as shown in Fig.1 (a) which is typical of the
damage sustained to a large number of water tanks of capacities ranging from 80 m3
to 1,000 m3
and as far away as 125km from the epicentre Fig.1 (b) shows a collapsed water tank in the
epicentre tract of the Bhuj earthquake.
Figure 1 (a) Damaged water (b) Collapsed water tank
International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 03, Issue 11; November - 2017 [ISSN: 2455-1457]
@IJRTER-2017, All Rights Reserved 2
II. LITARATURE AND REVIEW
Housner (1963) proposed two mass model for elevated tank which is more appropriate and is being
commonly used in most of the international codes including draft code for IS: 1893 (part - II).The
pressure generated within fluid due to the dynamic motion of the tank can be separated into the
impulsive and convective parts. When a tank containing liquid with a free surface is subjected to
horizontal earthquake ground motion, tank wall and liquid are subjected to horizontal
acceleration. Kalani and Salpekar (1978) their study is regarding different staging configuration,
which give a comparative study between conventional and matrix methods of analysis for staging of
overhead water tanks. S.C. Dutta, et al, (2000), studied torsion response of RC elevated water tanks
and have failed during past earthquakes owing to large torsion response. Considerable torsional
response may occur due to accidental eccentricity if the uncoupled torsional and lateral natural
periods of the tanks are closely spaced. Durgesh (2003).The performance of elevated water
tank in7.7 magnitude Bhuj earthquake of January 26th
, 2001 was studied. Many of the elevated
water tanks which were collapsed during the Bhuj earthquake were studied.
The conclusions arrived from them were, strength analysis of a few damaged shaft type staging‟s
clearly shows that all of them either met or exceeded the strength requirements of IS:1893-1984,
however, they were all found deficient when compared with requirements of the International
Building Code.
III. SEISMIC ANALYSIS OF CIRCULAR WATER TANK WITH SHAFT STAGING
Capacity of tank is 200 kilolitres and is supported on R.C shaft staging. In this study, five
different heights of staging 8, 11, 14, 17 and 20 m are considered. Details of various components are
as shown in Table1.
Table 1 Sizes of various components
Figure 2 Details of shaft staging water tank
Component Size (mm)
Roof slab 130 thick Wall 300 thick
Floor slab 200 thick
Circular ring beam 500×600 Gallery 110 thick
Thickness of shaft 180 thick
Diameter of tank 8120
Diameter of shaft 6480
International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 03, Issue 11; November - 2017 [ISSN: 2455-1457]
@IJRTER-2017, All Rights Reserved 3
3.1 LUMPED MASS MODEL METHOD
(When the tank is empty condition and full condition)
Table 2 Base shear
Table 3 Base moment
Figure 3 Base shear (Tank empty condition)
0
50
100
150
200
250
II III IV V
Ba
se s
hea
r(k
N)
Zone
Chart-1
8m
11m
14m
17m
20m
Zone Base
shear
(kN)
(8 m)
Base
shear
(kN)
(11m)
Base
Shear
(kN)
(14 m)
Base
shear
(kN)
(17
m)
Base
shear
(kN)
(20m
) Empt
y
Ful
l
Emp
ty
Full Empt
y
Full Empt
y
Full Emp
ty
Full
II 28 6
8
3
9
9
1
44 101 48 109 5
7
118
III 56 13
5
7
9
182 88 202 98 218 114 236
IV 70 16
9
9
7
232 109 252 122 273 143 294
V 111 27
0
156 371 175 403 195 436 228 470
Zone
Base
moment
(kN_m)
(8 m)
Base
moment
(kN_m)
(11 m)
Base
moment
(kN_m)
(14 m)
Base
moment
(kN_m)
(17 m)
Base
moment
(kN_m)
(20 m) Empt
y
Full Empt
y
Full Empt
y
Full Empt
y
Full Empt
y
Full
II 273 661 494 1157 686 1584 911 2040 1235 2553
III 545 1313 998 2313 1371 3167 1823 4047 2470 5105
IV 681 1643 1235 2949 1713 3957 2278 5096 3087 6381
V 1079 2625 1976 4719 2742 6333 3644 8160 4939 1020
9
International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 03, Issue 11; November - 2017 [ISSN: 2455-1457]
@IJRTER-2017, All Rights Reserved 4
Figure 4 Base shear (Tank full condition)
Figure 5 Base moment (Tank empty condition
Figure 6 Base moment (Tank full condition)
3.2 Hydrodynamic Pressure
Table 4 Hydrodynamic pressure on tank wall for staging height 8 m, 11 m in (N/m2)
(y)
m
y/h
Zone II Zone III Zone IV Zone V
8 m 11 m 8 m 11 m 8 m 11 m 8 m 11 m
0 0 0 0 0 0 0 0 0 0
1 \0.22
2
26.84 33.04 53.69 66.08 67.1
1
82.6
0
107.38 132.1
6 2 0.44
4
46.89 57.93 93.97 115.66 117.4
6
144.5
7
187.94 231.3
2 3 0.66
6
60.42 74.36 120.85 148.73 151.0
6
185.9
2
241.70 297.4
7 4 0.88
8
67.15 82.65 134.31 165.31 167.8
9
206.6
4
268.63 330.6
2 4.5 1 68.01 83.70 136.02 167.41 187.5
8
209.2
6
300.12 334.8
2
0
100
200
300
400
500
II III IV V
Ba
se s
hea
r (k
N)
Zone
Chart-2
8m
11m
14m
17m
20m
0
1000
2000
3000
4000
5000
6000
II III IV V
Mo
men
t (k
N_
m)
Zone
Chart-3
8m
11m
14m
17m
20m
0
2000
4000
6000
8000
10000
12000
II III IV V
Mo
men
t (k
N_
m)
Zone
Chart -4
8m
11m
14m
17m
20m
International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 03, Issue 11; November - 2017 [ISSN: 2455-1457]
@IJRTER-2017, All Rights Reserved 5
Table 5 Hydrodynamic pressure on tank wall for staging height 14 m, 17 m in (N/m2)
(y)
m
y/h
Zone II Zone III Zone IV Zone V
14
m
17
m
14 m 17 m 14 m 17 m 14 m 17 m
0 0 0 0 0 0 0 0 0 0
1 0.22
2
37.1
6
39.3
3
74.3
3
78.4
6
92.9
2
98.0
1
148.6
7
156.9
3 2 0.44
4
65.0
5
68.6
7
130.1
1
137.3
4
162.6
4
171.5
6
260.2
3
274.6
9 3 0.66
6
83.6
6
88.3
1
167.3
3
176.6
2
209.1
6
220.6
2
334.6
6
353.2
5 4 0.88
8
92.9
8
98.1
5
185.9
7
196.3
1
232.4
7
245.2
1
371.9
5
392.6
2 4.5 1 94.1
7
99.4
0
188.3
4
198.8
0
235.4
2
248.3
3
376.6
8
397.6
0 Table 6 Hydrodynamic pressure on tank wall for staging height 20 m in (N/m2)
Table 7 Hydrodynamic pressure on bottom of the tank for various heights of staging horizontal distance
3.765 m from the centre
(y) m y/h Zone II Zone III Zone IV Zone
V 0 0 0 0 0 0
1 0.222 41.298 83.59 103.2
4
165.19
2 2 0.444 72.28 144.5
7
180.7
2
289.15
3 0.666 92.96 185.9
2
232.4
0
371.84
4 0.888 103.32 206.6
4
258.3
0
413.28
4.
5
1 104.63 209.2
6
261.5
8
418.53
Height
of
staging
Pressure on bottom of the
tank(N/mm2) Zone II Zone III Zone IV Zone
V 8 m 188.17 3
7
6
.
3
5
470.44 752.7
1 11 m 188.17 376.35 470.44 752.7
1 14 m 211.70 423.40 529.25 846.8
0 17 m 223.46 446.13 558.12 893.2
4 20 m 235.22 470.44 588.00 940.8
9
International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 03, Issue 11; November - 2017 [ISSN: 2455-1457]
@IJRTER-2017, All Rights Reserved 6
Figure 7 Hydrodynamic pressure for 8 m
Figure 8 Hydrodynamic pressure for 11 m
Figure 9 Hydrodynamic pressure for 14 m
Figure 10 Hydrodynamic pressure for 17 m
0
0.2
0.4
0.6
0.8
1
1.2
0 200 400y
/h
Hydrodynamic Pressure (N/m2 )
Chart -5Zone II Zone III Zone IV Zone V
0
0.5
1
1.5
0 200 400
y/h
Hydrodynamic Pressure (N/m2 )
Chart-6Zone II Zone III Zone IV Zone V
0
0.2
0.4
0.6
0.8
1
1.2
y/h
Hydrodynamic Pressure (N/m2 )
Chart 7Zone II Zone III Zone IV Zone V
0
0.2
0.4
0.6
0.8
1
1.2
0 200 400
y/h
Hydrodynamic Pressure (N/m2 )
Chart-8Zone II Zone III Zone IV Zone V
International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 03, Issue 11; November - 2017 [ISSN: 2455-1457]
@IJRTER-2017, All Rights Reserved 7
Figure 11 Hydrodynamic pressure for 20 m
Figure 12 Hydrodynamic pressure bottom of the tank
3.3 TWO MASS MODEL METHOD (When the tank is empty condition and full
condition)
Table 8 Base shear
Zon
e
Base
shear
(kN)
(8 m)
Base
shear
(kN)
(11m)
Base
shear(kN
) (14 m)
Base
shear
(kN)
(17
m)
Base
shear
(kN)
(20 m)
Empty Full Empt
y
Full Empt
y
Full Empt
y
Full Empt
y
Full
I
I
76 106 101 141 128 304 134 313 141 323
III 121 147 164 226 204 485 215 500 226 515
IV 182 205 246 339 305 730 322 753 \338 776
V 274 298 368 508 458 1094 483 1129 507 1163
Table 9 Base moment
Zon
e
Base
moment
(kN-m)
(8 m)
Base
moment
(kN-m)
(11 m)
Base
moment
(kN-
m) (14
m)
Base moment
(kN-m) (17
m)
Base
moment
(kN-
m) (20
m) Empt
y
Full Empt
y
Full Empt
y
Full Empty Full Empt
y
Full
II 735 873 1285 1852 1998 4955 2374 6039 3059 7180 III 1176 1413 2080 2962 3197 7908 3798 9638 4894 1246
0 IV 1763 2120 3120 4442 4795 1191
0
5697 14514 7340 1725
8 V 2659 3177 4669 6662 7192 1785
0
8545 21770 \1101
0
2587
7
0
0.2
0.4
0.6
0.8
1
1.2
0 200 400 600y
/h
Hydrodynamic Pressure (N/m2 )
Chart-7Zone II Zone III Zone IV Zone V
0
200
400
600
800
1000
Zone II Zone III Zone IV Zone V
Pre
ssu
re N
/mm
2
Zone
Chart -9
8 m
11 m
14 m
17 m
20 m
International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 03, Issue 11; November - 2017 [ISSN: 2455-1457]
@IJRTER-2017, All Rights Reserved 8
Figure 13 Base shear (tank empty condition)
Figure 14 Base shear variation (tank full condition)
Figure 15 Base moment (tank empty condition)
0
100
200
300
400
500
600
II III IV V
Ba
se s
hea
r (k
N_
m)
Zone
Chart -10
8m
11m
14m
17m
20m
0
200
400
600
800
1000
1200
1400
II III IV V
Ba
se s
hea
r (k
N_
m)
Zone
Chart-11
8m
11m
14m
17m
20m
0
2000
4000
6000
8000
10000
12000
II III IV V
Mo
men
t (k
N_
m)
Zone
Chart -12
8m
11m
14m
17m
20m
International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 03, Issue 11; November - 2017 [ISSN: 2455-1457]
@IJRTER-2017, All Rights Reserved 9
Figure 16 Base moment (tank full condition)
From the above results Base shear and Base moment increases when height of staging is increases from
8 m height of staging to 20 m height of staging.Base shear and Base moment increase from Zone –II to
Zone –V. Base shear is lower value for the tanks are having Zone-II when compared to Zone-V. Base
shear is greater value for Zone –V and staging height is 20 m.
3.4 Hydrodynamic pressure
Table 10 Hydrodynamic pressure values at the base
Table 11 Hydrodynamic pressure values at the base of the wall for 8 m, 11 m staging height of the tank.
0
5000
10000
15000
20000
25000
30000
II III IV VM
om
ent
(kN
_m
)Zone
Chart -13
8
12
14
17
20
(y) m “ Piw” values for different zones in N/mm
2
y/h Qiw Zone 2 Zone 3 Zone 4 Zone 5
0 0 0.776 3562.6
7
5686.5
8
8564.1
3
12846.1
9
1 0.222 0.738 3388.2
1
5408.1
1
8144.7
5
12217.1
2
2 0.444 0.623 2860.2
4
4565.3
8
6875.5
8
10313.3
7
3 0.666 0.431 1978.7
5
3158.3
9
4756.6
2
7134.93
4 0.888 0.163 748.34 1194.4
7
1798.9
0
2698.36
4.5 1 0 0 0 0 0
(y)
m “ Piw” values for different zones in N/mm
2
y/h Qiw Zone 2 Zone 3 Zone 4 Zone 5
0 0 0 0.776 1708.34 2730.54 4095.81
1 0.222 0.222 0.738 1624.32 2596.25 3894.38
2 0.444 0.444 0.623 1370.11 2189.94 3284.91
3 0.666 0.666 0.431 947.88 1515.05 2272.58
4 0.888 0.888 0.163 357.60 571.58 857.38
4.5 1 1 0 0 0 0
International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 03, Issue 11; November - 2017 [ISSN: 2455-1457]
@IJRTER-2017, All Rights Reserved 10
Figure 17 Hydrodynamic pressure (14 m, 17 m, 20 m)
Figure 18 Hydrodynamic pressure (8 m, 11 m)
Figure 19 Impulsive hydrodynamic pressure on the base slab
Figure 20 Fig. 20 Convective hydrodynamic pressure on wall
0
0.2
0.4
0.6
0.8
1
1.2
0 5000 10000 15000 20000
y/h
Hydrodynamic Pressure (N/m2 )
Chart -14
Zone 2 Zone 3 Zone 4 Zone 5
0
0.2
0.4
0.6
0.8
1
1.2
0 2000 4000 6000
y/h
Hydrodynamic Pressure (N/m2 )
Chart -15Zone 2 Zone 3 Zone 4 Zone 5
0
2000
4000
6000
8000
II III IV V
Hy
dro
dy
na
mic
pre
ssu
re (
N/m
2)
Zone
Chart -1611m, 8m
20 m,17 m,14 m
0
100
200
300
400
500
600
II III IV V
Pre
ssu
re N
/mm
2
zone
Chart-17 Pressure
International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 03, Issue 11; November - 2017 [ISSN: 2455-1457]
@IJRTER-2017, All Rights Reserved 11
Table 12 Convective Hydrodynamic Pressure
Table 13 Impulsive hydrodynamic pressure on the base slab (y= 0)
Table 14 Convective pressure at the base of wall
Figure 21 Convective Hydrodynamic Pressure at the base the wall
Table 15 Convective pressure on top of base slab
Zone Pressure on slab(N/m
2)
Zone – V 540
Zone – IV 360
Zone – III 240
Zone – II 150
0
500
1000
1500
2000
II III IV V
Pre
ssu
re N
/mm
2
Zone
Chart-18 Pressure
Zone Pressure on wall(N/m
2)
Zone – V 540
Zone – IV 360
Zone – III 240
Zone – II 150
ZONE Staging height
20m,17m, 14mN/m2
Staging height
11m N/m2
Staging height
8m N/m2
Zone – V 6560 3080 1837
Zone – IV 4380 2040 1225
Zone – III 2900 1360 823
Zone – II 1820 850 508
Zone Pressure on
wall(N/m2) Zone – V 1480
Zone – IV 990
Zone – III 660
Zone – II 410
International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 03, Issue 11; November - 2017 [ISSN: 2455-1457]
@IJRTER-2017, All Rights Reserved 12
Figure 22 Convective Hydrodynamic Pressure on top the base slab
Table 16 Pressure Due to Wall Inertia
Zone Pressure on wall (N/m
2)
Zone – V 440
Zone – IV 320
Zone – III 200
Zone – II 120
Figure 23 Pressure due to wall inertia
Table 17 Pressure Due to Vertical Excitation
Zone Pressure on wall (N/m2)
II 2200
III 3530
IV 5300
V 7940
Figure 24 Pressure due to vertical excitation
0
200
400
600
II III IV V
Pre
ssu
re N
/mm
2
Zone
Chart-19 Pressure
0
100
200
300
400
500
II III IV V
Pre
ssu
re N
/mm
2
Zone
Chart -20 Pressure
0
2000
4000
6000
8000
10000
II III IV V
Pre
ssu
re N
/mm
2
Zone
Chart -21 Pressure
International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 03, Issue 11; November - 2017 [ISSN: 2455-1457]
@IJRTER-2017, All Rights Reserved 13
III CONCLUSION
Seismic analysis is carried out for different shaft staging heights which are 8 m, 11 m, 14m, 17m
and 20m respectively. The analysis is carried out as per one mass model and Two mass model by
considering four seismic Zones from Zone –II to Zone –V and also analysis is carried out for
hydrodynamic pressure and sloshing wave height.
From the results, following conclusions have been made.
1. The base shear increases from Zone –II to Zone –V for any height of staging and also with
increases of staging height base shear also increases.
2. The base shear increases about 55-60% in one mass model from tank empty to tank full
condition.
3. The base shear increases about 25-30% in 8 m and 11 m height of staging and 50-60% in 14
m, 17 m, and 20 m Two mass model from tank empty to tank full condition.
4. The base shear increases about 55-65% for Tank empty condition in single mass model to
Two mass model.
5. The base shear increases about 55-65% for Tank full condition in single mass model to two
mass model.
6. The base moment increases from Zone –II to Zone –V for any height of staging and also with
increases of staging height base moment also increases.
7. The base moment increases about 55-60% in One mass model from tank empty to tank full
condition.
REFERENCES I. BIS 1984 IS: 1893-1984 Criteria for earthquake resistant design structures, Bureau of Indian Standards,
New Delhi.
II. BIS 2002 IS: 1893 (Part-1) -2002 Criteria for Earthquake Resistant Design of Structures, General Provisions
of Buildings and Bureau of Indian standards, New Delhi, India. (Fourth Revision)
III. BIS 2002 Draft IS: 1893-2002 (Part-II, Liquid Retaining Tanks) Criteria for Earthquake Resistant Design of
Structures, Bureau of Indian standards, New Delhi, India.
IV. Bojja.Devadanam , M K MV Ratnam , Dr.U RangaRaju, “Effect of Staging Height on the Seismic Performance
of RC Elevated Water Tank”, International Journal of Innovative Research in Science, Engineering and
Technology, January 2015,
V. Issue 1, Vol. 4, PP. 18568- 18575.
VI. Chirag N. Patel and H. S. Patel, ―Former Failure Assessments of RC Elevated Water Tanks: Literature
Review‖, GIT-Journal of Engineering and Technology
VII. (ISSN 2249 - 6157), 2012.
VIII. G. W. Housner, “The Dynamic Behaviour of Water Tanks, Bulletin of the Seismological Society of America,
Vol.53, No.2, pp.381-387, Feb1963” IX. Housner, G.W., “Dynamic analysis of fluids in containers subjected to acceleration”, Nuclear Reactors
and Earthquakes, Report No. TID 7024, U.S. Atomic Energy Commission, Washington D.C, 1963.
X. 8.IITK-GSDMA guidelines for seismic design of liquid storage tanks.
XI. IS: 11682-1985, Criteria for Design of RCC Staging For Overhead Tanks (1985),Bureau of Indian Standards,
New Delhi.
XII. IS: 3370 (Part II) – 2009 code of practice for concrete structures for the storage of liquids part -II reinforced
concrete structures (First Revision).