Seismic and Wind Load Comparative Analysis of Overhead Intake Water Tanks with Unfilled, Half Filled and Completely Filled Condition in Earthquake III to V-Zone

Abstract

Safe and pure water is most important elements for human being to prolong healthy life. Reinforced cement concrete overhead water tanks are largely used to offer safe drinking water. There are several water supplying systems having in developing countries, like India, where population is increasing on daily basis, that\'s why there is necessary to construct large amount of water tanks. Previous designs of water tank completed by working stress method given in IS: 3370 1965. From past records we can say that, many of reinforced concrete elevated water tanks were severely damaged or collapsed during the earthquakes and cyclones all over the world. Generally, these are happening because of the failure of supporting system which states that the supporting system of the elevated tanks has more serious significance than the other structural parts of tanks. Mostly the damages observed due to the seismic events and cyclonic events. This happens might be because of the lack of knowledge regarding the proper behaviour of supporting system of the tank against dynamic effect and also due to inappropriate geometrical selection of staging patterns. In order to require proper head of water, its generally require to construct elevated water tank, generally these types of water tank is used for storing water for fulfil daily needs. For storing water R.C.C. structure is most favourable structures amongst others structure. Elevated Water Tanks is widely used for storage large amount of water for supply system and its play vital role in seismic areas. Water Tanks may be flaw because of scarcity of water or problem with the peoples to suppress the flames during seismic movement. The seismic movement is responsible for different failure such as ground surface failure and deficiency of support to the stages. The aim of this Research work is Response spectrum analysis, seismic analysis of overhead Intze Water Tanks with unfilled, half filled and completely filled condition in earthquake 3rd to 5th Zone. This whole analysis is done by STAAD Pro V8i SS6. The seismic zones of Zone-III, Zone-IV, Zone-V and the equivalent lateral load characteristics have been taken from IS 1893 (PART 1)-2002 & draft code IS 1893 (Part 2) and IS 875 (PART 3) - 1987. For this different condition of water tank. It has Intze shape. Water Tank having 1800000 litres holding capacity and supported on RCC frame stages height 20 m & 30 m under seismic movement loads provide according to code section 2 of IS 1893:2002.

Introduction

• Water tanks are critical infrastructure for storing vital liquids like water and petroleum, used in residential, commercial, and industrial settings.

• Tanks serve multiple purposes: clean water supply, fire suppression, wastewater treatment, and industrial processes.

• The structure of a tank—including its architecture, position, and location-specific water demand—influences how water is stored and distributed.

???? Seismic Concerns and Safety

• Earthquakes pose serious risks to water tanks, especially elevated tanks with heavy masses mounted on slender support structures.

• Earthquakes can cause:

  • Structural failure

  • Water shortages

  • Increased fire risk

  • Public panic and infrastructural damage

• Structures must be designed to resist lateral forces like those from earthquakes and wind.

???? Types of Water Tanks

• By Position:

  1. Underground

  2. Surface-level

  3. Overhead/Elevated

• By Shape:

  • Rectangular, Square, Circular

  • Intz, Domed, Coned, Spherical Bottoms

???? Literature Review Highlights

Several researchers have studied seismic effects on water tanks:

• Ramazan Livaoglu & Adem Dogangun (2006):

  • Compared seismic response based on ground types using EC-8 and TEC-06 codes.

  • Found significant variation in displacement and base shear depending on soil class.

• F. Omidinasab & H. Shakib (2008):

  • Analyzed an Intze tank using FEM models under seven different earthquake records.

  • Evaluated sloshing, base shear, and overturning moments.

• Suchita Hirde et al. (2011):

  • Studied impact of soil condition and tank height in different seismic zones across India using 240 models.

• Ayazhussain Jabar & H.S. Patel (2012):

  • Investigated supporting device behavior and hydrodynamic pressures under different filling levels.

• Chirag N. Patel & H. S. Patel (2012):

  • Focused on failure of tank support systems during earthquakes, suggesting improved staging patterns.

• Other researchers like Ibrahim, Karamanos, and Patkas analyzed sloshing effects and dynamics in cylindrical/spherical tanks.

?? Types of Loads on Water Tanks

1. Dead Loads: Self-weight of concrete components like dome, walls, columns, etc.

2. Imposed Loads: Maintenance loads as per IS: 875 (0.75 kN/m²).

3. Water Loads: Pressure increases linearly with depth; formula:

   p=γwh(γw=10kN/m3)p = γ_w h \quad (γ_w = 10 kN/m^3)p=γw?h(γw?=10kN/m3)

4. Wind Loads: Calculated using IS: 875 Part 3. Factors: terrain (k2), topography (k3), structure size, etc.

???? Seismic (Hydrodynamic) Analysis

• Seismic forces on tanks are divided into:

  • Impulsive Forces: From the base water mass attached to tank walls.

  • Convective Forces: From the sloshing of upper water mass.

? Two-Mass Model (Housner, 1963)

• Widely accepted method to model seismic behavior of liquid-filled tanks.

• Represents the tank fluid using two masses:

  • One for impulsive pressure

  • One for convective (sloshing) pressure

• Used in IS 1893 (Part II) seismic design code.

???? Lateral Stiffness of Staging

• Measured by applying a unit force at the center of gravity (C.G.) of the tank and calculating displacement.

• Formula:

  Ks=10DisplacementK_s = \frac{10}{\text{Displacement}}Ks?=Displacement10?

  where Ks is the lateral stiffness (kN/m).

???? Software & Modeling

• STAAD Pro V8i SS6 and SAP2000 used for:

  • FEM modeling

  • Simulating structural behavior under seismic loads

  • Evaluating performance under different tank shapes, capacities, and soil conditions

Conclusion

In this presentation, the seismic behavior of tanks has significantly changed, along with concerned responses approximating base moment, stiffness, displacement, B.S., etc. Supported systems using for proper adjustments. The study\'s conclusion highlights the importance of using the right supporting configuration to prevent elevated water tanks from suffering severe damage or collapse during an earthquake. The main excitation factor for reactions like the O.M., roof displacement, and B.S.F., earthquake properties in different zones are compared and equated. 1) In the first case study of the IIIrd zone, a storage tank with a 20-meter staging height, basically bracing (Ks= 26315.79kN/m) is either more suited than radial bracing (Ks= 35087.72kN/m) in this instance. 2) The roof displacement for the Basically (70mm) and Radially (62mm) are greater than limitation value (54mm) in Vth zone for similar Case study-1 liquid storing tank with a 20-meter staging height. 3) In Case Studies 1 and 2, storing tank with a height of 20 and 30 meters, respectively, the Radially, B.S. and Base moments are comparably bigger than those of Basically bracing, have jeopardize staging parts\' reinforcing plan. 4) After altering the diameters of the bracing beams in Vth for similar Case Study-2 storing with ht. Of staging, it was found that the minimum staging stiffness (Ks) value needed to keep roof displacements within acceptable bounds was 11013kN/m.

References

[1] Anup Y Naik1, Rakshan K M2, Ashok P G3 (2015), Seismic Analysis of Completely Buried Rectangular Concrete Reservoir, International Research Journal of Engineering and Technology (IRJET), PP:709-714. [2] Ayazhussain M Jabar, H S Patel (2012),“Seismic behaviour of RC elevated water tank under different staging pattern and earthquake characteristics”, International Journal of Advanced Engineering Research and Studies, IJAERS, Vol.I, Issue III, Apr-June, 293-296. [3] Chirag N Patel and H S Patel (2012), “Supporting systems for reinforced concrete Elevated water tanks”, International Journal of Advanced Engineering Research and Studies, IJAERS, Vol.II, Issue I, Oct.-Dec., 68-71. [4] Chirag N Patel, Shashi N Vaghela, H. S. Patel (2012), “Sloshing Response of Elevated Water Tank over alternate column proportionality”, International Journal of Advanced Engineering Technology, IJAERS, Vol.III, Issue IV, Oct.-Dec., 60-63. [5] Durgesh C Rai (2003), “Performance of elevated tanks in Mw 7.7 Bhuj earthquake of January 26th, 2001”. Department of Civil Engineering, IIT Kanpur, 112, No. 3, pp. 421- 429. [6] F. Omidinasab and H Shakib (2008) “Seismic Vulnerability of Elevated Water Tanks Using Performance Based-Design”, The 14th World conference on Earthquake Engineering, October 12-17. [7] George W Housner (1963), “The Dynamic behaviour of Water Tanks”, Bulletin of the Seismological Society of America, Vol. 53, No. 2, pp. 381-387. [8] H. Kazema, S. Mehrpouyab (2012), Estimation of Sloshing Wave Height in Broad Cylindrical Oil Storage Tanks Using Numerical Methods, Journal of Structural Engineering and Geotechnics, PP:55-59 [9] H. Shakib, Omidinasab and M T Ahmadi (2010), “Seismic Demand Evaluation of Elevated Reinforce Concrete Water tanks”, International Journal of Advanced Engineering Research and Studies, Vol. 8, No. 3. [10] Halil Sezena, Ramazan Livaoglub, Adem Dogangunc (2008), Dynamic analysis and seismic performance evaluation of above-ground liquid-containing tanks, Engineering Structures 30 (2008) 794–803. [11] HasanJasim Mohammed (2011), Economical Design of Water Concrete Tanks, European Journal of Scientific Research, pp. 510-520.

Copyright

Copyright © 2025 Aditya Agrawal, Dr. Rakesh Gupta, Dr. Mukesh Pandey. 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.