Comparative Analysis of Circular and Rectangular Water Tank in Severe Seismic Zones

Abstract

In the present work a comparative analysis for finding the optimized shape of water tank was performed. All models were then analyzed with action of loads and loading combinations prescribed by IS 1893 using STAAD PRO V8i SS5 series software for getting the most efficient and precise results. Total 08 models will be analyzed as per IS 1893 (part2), which are divided as 04 models of circular shape tank in all 04 seismic zones with tank empty condition and 04 models of rectangular shape tank in all 04 seismic zones with tank full condition after detailed analysis it was found that In tank full condition, rectangular tank shows lower values in zone -2 and zone-4 the increment is not much higher but in zone-3, circular shape shows very high about 19.92% higher values than rectangular tank. So, it can be concluded that use of rectangular shapes will prove efficient in all zones especially in zone-3. From this comparative graph it can be seen that rectangular tank gives higher values of displacement in all zones while circular tank shows lowest values in all zones. In zone-2 rectangular tank gives 4.45% and in zone-4 it gives 13.67% higher values than circular than.

Introduction

Introduction

Water is essential for life and must be stored safely and efficiently, especially in disaster-prone regions like India. Elevated Reinforced Concrete (RC) water tanks, particularly circular or rectangular in shape, are commonly used for this purpose. Their design must consider structural efficiency and resistance to natural disasters like earthquakes, which are a significant threat in over 60% of India's land area per seismic code IS: 1893 (Part I): 2002.

Literature Review

Key findings from previous research include:

• T. Karanjekar: Circular tanks are more material-efficient and economical than rectangular tanks.

• Krishna Rao M.V: Seismic analysis using newer IS codes shows significantly higher base shear and hydrodynamic pressure compared to older codes. Circular tanks are evaluated across seismic zones and soil types.

• Kishor G. Bhagat: The limit state method (IS 3370:2009) results in thinner walls and reduced material usage compared to the working stress method.

• Jay Shah: The structural performance of Intze-type tanks with various bracing configurations shows that X-bracing provides maximum stiffness. Partial tank fill is the most critical condition.

• Mor Vyankatesh K: Larger capacity tanks face greater seismic risks. The study uses STAAD Pro and IS 1893 (Part 2): 2014 for dynamic analysis.

Methodology

The project is executed in three phases:

Phase I – Planning

• Establish need: Water scarcity in Indian villages necessitates efficient tank designs.

• Review literature and codes to guide the design process.

• Decide flow of work and modeling strategy.

Phase II – Study and Modeling

• Detailed study of tank types and parameters.

• Analyze earthquake effects and loads per IS-1893:2002.

• Consider material constants (M30 concrete, Fe-415 steel) and tank shapes (circular, rectangular, square).

• Use static coefficient method for seismic analysis due to its conservative output.

Phase III – Analysis and Comparison

• Models analyzed using STAAD Pro V8i SS5.

• 16 models created across seismic zones and tank fill levels.

• Structural responses such as base shear, overturning moment, reactions, displacement, and reinforcement needs are compared.

Design & Modeling

• Target population: 1584 (based on projected growth to 2051).

• Water consumption: 135 lpcd → 213.84 m³ tank capacity.

• Tank height: 4 m + 0.3 m freeboard.

• Tank types:

  • Circular: Diameter = 8.25 m

  • Rectangular: 6 m × 8.91 m

• Seismic zones: II, III, IV, V

• Software used: STAAD Pro

Results & Discussion

1. Base Shear (kN)

• Rectangular tanks generally show lower base shear except in Zone III where circular tanks have ~20% higher base shear.

• Rectangular tanks preferred due to efficiency in seismic performance.

2. Overturning Moment (kN·m)

• Rectangular tanks show consistently lower overturning moments in all zones.

• Most significant difference in Zone III.

3. Base Reactions (kN)

• Rectangular tanks display higher base reactions.

• Suggests they are capable of better load distribution but may require stronger foundations.

4. Displacement (mm)

• Circular tanks show lower displacements in all zones.

• In Zone IV, rectangular tanks have up to 13.67% higher displacement.

5. Reinforcement in Staging (kN)

• Circular tanks require more reinforcement, especially in higher seismic zones.

• Rectangular tanks use less reinforcement, making them more economical.

Conclusion

1) Design of tank should be governed by tank full condition. 2) Rectangular tank gives lowest values of base shear, overturning moment and reactions. 3) Rectangular tank gives higher values of displacements, So more bracings are required to control displacement. 4) In low seismic zone there any shape can be used but as seismicity increases emphasis should be given on rectangular tank. 5) For the same capacity and seismic parameters rectangular tank gives more stable results than circular water tank.

References

[1] Seismic Analysis of Overhead Circular Water Tanks – A Comparitive Study IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308 Krishna Rao M.V1, Rathish Kumar. P2, Divya Dhatri. K3 [2] Comparative Study of RCC Water Storage Tank with IS3370 Old and New Provision IJSRD - International Journal for Scientific Research & Development| Vol. 6, Issue 05, 2018 | ISSN (online): 2321-0613 Kishor G. Bhagat1 Dr. Pankaj Singh2 [3] Comparative Study on Behaviour of Intze type Water Tank with Different Lateral Load Resisting Structural Systems International Journal of Technical Innovation in Modern Engineering & Science (IJTIMES) Impact Factor: 5.22 (SJIF-2017), e-ISSN: 2455-2585 Volume 5, Issue 04, April-2019 Jay Shah1, Dr. Major Chaitanya S. Sanghvi2, Abbas Jamani3 [4] Dynamic Analysis of Rc Elevated Water Tank Frame Staging Supported Mor Vyankatesh K ¹, More Varsha T. ² [5] Seismic Analysis of RC Elevated Water Tanks International Journal of Scientific & Engineering Research, Volume 6, Issue 12, December-2015 ISSN 2229-5518 Pradnya V. Sambary1, D.M. Joshi2 [6] A Survey on Dynamic Analysis of Elevated Water Tank for Different Staging Configuration International Journal of Computer Science and Mobile Computing a Monthly Journal of Computer Science and Information Technology ISSN 2320–088X IMPACT FACTOR: 6.017 IJCSMC, Vol. 6, Issue. 5, May 2017, pg.194 – 201 Aliakbar Qutubuddin Ali1, Deepa P. Telang2 [7] Review on Seismic Analysis of Elevated Water Tank with Variations of H/D Ratio and Container Shape International Journal of Computer Science and Mobile Computing a Monthly Journal of Computer Science and Information Technology ISSN 2320–088X IMPACT FACTOR: 6.017 IJCSMC, Vol. 6, Issue. 5, May 2017, pg.202 – 208 Mayank Gopal Manwani1, Deepa P. Telang2 [8] Effect of Staging Height on Seismic Performance of RC Elevated Water Tank International Conference on Advances in Civil and Mechanical Engineering Systems, 23-24 Dec.2014 Government College of Engineering, Amravati in association with SVNIT, Surat, India http://acmes2014.in Dr. Suchita Hirde1, Mr. Umesh L. Raygandhi-Shaha2 [9] Review Study on Comparison between Static and Dynamic Analysis of RCC Water Tank International Journal of Research in Advent Technology (IJRAT) (E-ISSN: 2321-9637) Special Issue National Conference “CONVERGENCE 2017”, 09th April 2017 Ms. Pranjali N. Dhage, Mr. Mandar M. Joshi [10] Comparison between Static and Dynamic Analysis of Elevated Water Tank International Journal of Scientific & Engineering Research, Volume 4, Issue 6, June-2013 2043 ISSN 2229-5518 Gaikwad Madhurar V., Prof. Mangulkar Madhuri N. [11] Comparative Study of Analysis of Elevated Water Tank Due to Earth Quake from Different Zones of Earth Quake International Journal of Constructive Research in Civil Engineering (IJCRCE) Volume 2, Issue 1, 2016, PP 22-29 ISSN 2454-8693 (Online) P.L.N. Saroja

Copyright

Copyright © 2025 Nivrutti V Datkar, Prof. A. R. Pohare. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.