Comparative study of shaft supported water tank and frame supported intze water tank using limit state method

1. Comparative study of shaft supported
and frame supported intze water tank
using limit state method
Guides:
Dr. B.A.SHAH
Dr. D.R.PANCHAL
Dr. H.J.SHAH
Prepared by:
Chintan Babubhai Maradiya
M.E. STRUCTURAL
ENGINEERING
SEMESTAR-4
FACULTY OF
TECHNOLOGY
AND ENGINEERING

2. Contents:
 Abstract
 Shaft supported intze tank
 Frame supported intze tank
 Parameters for different tanks
 Results
 Conclusion
 References

3. Abstract:
 The main aim of this study is to find which type of
tank is economical , shaft supported intze tank or
frame supported intze tank and why. Analysis and
design of elevated shaft supported intze tank is
carried out in Microsoft excel and analysis and
design of container of frame supported intze tank is
carried out in Microsoft excel and analysis and
design of staging of frame supported intze tank is
carried out in staad pro. software. Comparison of
base shear, base moment, quantity of concrete,
quantity of steel is carried out for shaft supported
and frame supported intze tank.

4. Shaft Supported Intze Tank:
 Shaft diameter is selected such
that it does not subjected to
tension in any of load
combination. The diameter of
shaft is governed by load case
0.9DL+1.5EQ .
 Lateral stiffness of shaft
supported tank is taken as
3EI/L3
 Load Cases:
1. 1.5(DL+LL)
2. 1.2(DL+LL±EQ)
3. 1.5(DL±EQ)
4. 0.9DL±1.5EQ

5. Frame Supported Intze Tank:
 Bracing System for frame
supported Intze tank is provided
as shown in figure. It is selected
so that we can provide stair at
centre and stair will not cause
any eccentricity during
 Load Cases:
1. 1.5(DL±EQ-X)
2. 1.5(DL±EQ-Z)
3. 0.9DL±1.5EQ-X
4. 0.9DL±1.5EQ-Z
5. 1.5(DL±EQX±0.3EQZ)
6. 1.5(DL±EQZ±0.3EQX)
7. 0.9DL±1.5(EQX ±0.3EQZ)
8. 0.9DL±1.5(EQZ ±0.3EQX)

6. Parameters:
 In top dome we had provided reinforcement in one layer
and we had taken minimum thickness of 100mm.
 Thickness of cylindrical wall of container is taken
minimum 200mm. Technically we can provide thickness
lesser than 200mm, but due to provision of
reinforcement in two layers with 45mm clear cover and
minimum criteria suggestion by R.D.Anchor, we had
taken 200mm minimum thickness.
 Reinforcements are also provided in two layers in
conical dome, bottom spherical dome and shaft staging.
 Rise of spherical dome is taken around D/6,where D is
base diameter of dome Angle of conical dome is kept
near to 45 degree as it is economical.

7. Table:1
Common parameters
S.B.C OF SOIL 200kN/m^2
Height of staging 20.5m
Depth of Staging Below G.L 2.35m
Internal Diameter of Stair shaft 2.15m
Seismic Zone 3
Importance Factor 1.5
Type of soil Medium
Grade of steel Fe415
Grade of concrete M30

8. Table:2
Parameters for Shaft supported Intze Tank for different capaciyy
Parameters 1000m^3 1500m^3 2000m^3
Rise of top dome(central) 2.8m 3.2m 3.3m
Diameter of cylindrical wall (inner) 17m 18.3m 20.5m
Assume Ht Of Cy. Wall(With Free
Board) 3.875m 4.96m 4.78m
Free board 0.3m 0.3m 0.35m
Height of conical dome 2m 2.4m 3.2m
Width of Conical Dome 2.2m 2.5m 3.2m
Rise of bottom dome(central) 2.05m 2.3m 2.3m
Diameter of main shaft 12.35m 13.05m 13.85m
Provided Shaft Thickness 250mm 250mm 250mm
Response Reduction Factor 2.5 2.5 2.5

9. Table:3
Parameters for Frame supported Intze Tank for different capacity
Parameters 1000m^3 1500m^3 2000m^3
Rise of top dome(central) 2.8m 3.2m 3.3m
Diameter of cylindrical wall (inner) 17m 18.3m 20.5m
Assume Ht Of Cy. Wall(With Free Board) 3.875m 4.94m 4.59m
Free board 0.3m 0.3m 0.35m
Height of conical dome 2m 2.4m 3.5m
Width of Conical Dome 2.1m 2.5m 3.525m
Rise of bottom dome(central) 2.1m 2.3m 2.3m
Diameter of frame 12.3m 12.8m 12.8m
Provided column diameter 500mm 650mm 650mm
Response Reduction Factor 4 4 4

10. Results:
Tank Capacity Shaft Supported Frame Supported
1000m^3 1078 193
15000m^3 1490 270
2000m^3 1823 311
Comparision of base Shear(kN)
Tank Capacity Shaft Supported Frame Supported
1000m^3 26908 5000
15000m^3 38479 7259
2000m^3 47959 8627
Comparision of base Moment(kNm)
Comparison of Base shear and base moment of earthquake
forces:
Table:4 Table:5
0
200
400
600
800
1000
1200
1400
1600
1800
2000
Base
shear
Capacity of Tank
Shaft Supported
Frame Supported
0
10000
20000
30000
40000
50000
60000
Base
Moment
Capacity of Tank
Shaft Supported
Frame Supported

11. Tank Capacity Shaft Supported Frame Supported
1000m^3 470 323
15000m^3 585 428
2000m^3 746 543
Comparision of Concrete Quantity(m^3)
Tank Capacity Shaft Supported Frame Supported
1000m^3 21981 24048
15000m^3 28984 32044
2000m^3 36861 41515
Comparision of Steel Quantity(kg)
Comparison of Quantity of concrete and steel:
Table:6 Table:7
0
100
200
300
400
500
600
700
800
Concrete
Quantity
(m^3)
Capacity of Tank
Shaft Supported
Frame Supported
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
Steel
Quantity
(kg)
Capacity of Tank
Shaft Supported
Frame Supported

12. Conclusion:
 From Above study we came to understand that
frame supported intze tank is over ally more
economical then Shaft supported intze tank.
Base shear and base moment of shaft supported
intze tank in to much higher compare to frame
supported intze tank, This is because of higher
stiffness of shaft and lower response reduction
factor. Concrete quantity of frame intze tank is
very less compare to shaft tank but steel quantity
of frame tank is more compare to shaft tank this
is because of ductile detailing of frame
supported intze tank.

13. Next work plan:
 Optimize both shaft supported and frame
supported intze tank by taking appropriate
dimensions of components.
 Optimize frame supported intze tank by
reducing the diameter of frame.
 Analyze and design the shaft supported intze
tank by taking response reduction factor 3.5.

14. Reference:(Indian standards)
1. IS3370 Part 1-2009(Code requirement of Concrete structure for
storage of liquid-General Requirements)
2. IS 3370 Part 2-2009(Code requirement of Concrete structure for
storage R.C.C Structure)
3. IS 1893 Part 1-2002(Code requirement of EQ-General provision
and building)
4. IS 1893 Part 2-2014(Code requirement of EQ-Liquid retaining
tanks)
5. IS 11682-1985 & Draft-2011(Code requirement of Design of
RCC Staging for overhead water tanks)
6. IS 13920-1993(Code requirement of Ductile detailing of
reinforced concrete structures subjected to seismic forces )
7. IS 875 Part 3-2015(Code requirement of wind loads)
8. IITK-GSDMA “guidelines for seismic design of liquid storage
tanks.”

15. Reference:(Papers )
9. Bhagyashree P. Kagelwar, DR. A. V. Patil(2016) “Economic
Design Of RC Elevared Water Tanks by IS3370-1965 and its
revision IS3370-2009” ,International Journel Of Pure and
Applied Research In Engineering and technology,; Volume 4
10. Bojja.Devadanam 1, M K MV Ratnam 2, Dr.U
RangaRaju(2015)“Effect of Staging Height on the Seismic
Performance of RC Elevated Water Tank” Vol. 4, Issue
1,International Journal of Innovative Research in Science,
Engineering and Technology
11. G. P. DESHMUKH, ANKUSH S. PATEKHEDE(April 2015)
“Analysis of Elevated Water Storage Structure Using Different
staging System”, ( International Journal of Advanced
Structures and Geotechnical Engineering)
12. KeyurY.Prajapati ,Dr.H.S.Patel,Dr.A.R.Darji(June
2014)“Analysis of Hybrid staging system for Elevated water
tank” ,Indian Journal Of Research.
13. Robert D.Anchor(1992). Design of Liquid Retaining Concrete
Structure,2nd Ed.Edward Arnold,London