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International Research Journal of Engineering and Technology (IRJET)

e-ISSN: 2395-0056

Volume: 10 Issue: 06 | Jun 2023

p-ISSN: 2395-0072

www.irjet.net

Seismic Evaluation of Base Isolated Overhead Water Storage Tank 1Arfat Rafiq, 2Mir Tabish Altaf, 3Shahid Rafeeq, 4Dr. Mohammad Umair 1M Tech student, Department of Civil Engineering, Jamia Millia Islamia, New Delhi, India

2 M Tech student, Department of Civil Engineering, Jamia Millia Islamia, New Delhi, India 3 B E student, Department of Civil Engineering, Jadavpur University, Kolkata, India

4Assistant Professor, Department of Civil Engineering, Jamia Millia Islamia, New Delhi, India

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Abstract - This paper presents the seismic analysis of

impact on the anticipated seismic load, are its dynamic properties. The seismic code IS: 1893(Part I): 2016 states that more than 60% of India is earthquake-prone. Elevated water tanks' seismic analyses differ from those of other structures in two ways:

reinforced concrete overhead water tank. An overhead water tank is analyzed for seismic zone V as per IS 1893: 2016 using SAP 2000 software. Non-linear time history analysis has been conducted to evaluate the behavior the OWT (Overhead Water Tank) at different water levels under the base fixed condition and base isolated conditions. The main parameters consider in this seismic analysis of OWT are lateral displacement, base shear and time period. From the analysis it is found that the response of the tank depends upon the support conditions, type of the quake, depth of water level in the tank and shows a complex behavior. The tank with fully filled gives maximum displacement in both the cases, maximum base shear and maximum time period. Tank with 75% water gives less displacement as compared to 50% water that is mainly due to strong sloshing effects in case of tank containing 75% water. Base isolation of overhead water tank does not give us rigid body motion of superstructure. There is a large relative displace at the staging levels.

1.INTRODUCTION

Elevated liquid storage tanks require more design seismic forces than other structures because they are less ductile and redundant, necessitating rigorous seismic analysis and exact determination of the design earthquake load.

The idealized two DOF systems for OWTs with and without water is composed of the impulsive mode and convective mode, as well as a single DOF. There won't be convective mode in the empty tank. Figure 1.4 illustrates the OWT's idealized structural design. When an OWT with enough free surface and water for the entire height is subjected to ground acceleration from an earthquake, the tank wall and water will both be excited horizontally. The water present in the tank's lower container will function as a mass that is rigidly attached to the tank wall during the earthquake excitation. It is known as impulsive mass. The sloshing effects will have an impact on the water in the upper part of the tank, and this mass is known as convective mass. Impulsive hydrodynamic pressure and convective hydrodynamic pressure, respectively, are terms used to describe the hydrodynamic pressure caused by impulsive mass and convective mass. When analyzing the modal behavior of filled tanks, a two-DOF system is split into two

Expected seismic load is dependent on a number of factors, including the area's seismicity, the kind of soil, the structure's dynamic properties, etc. The structure's natural time period and damping, which have a significant

Impact Factor value: 8.226

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1.1 SPRING-MASS IDEALIZATION OF OVERHEAD WATER TANK

Elevated reservoirs are considered important structures that must continue to function as soon as a large earthquake happens, among other reasons to aid in relief operations and stop fires from spreading. The reservoirs are raised by creating a circular shaft or by staging. The columns and horizontal braces of the structural framework used for staging normally transfer the load to the foundation. Reinforced concrete elevated water tanks were proven to perform poorly under jolts of earthquakes. Previous earthquakes damaged the supports of multiple tall water tanks despite their moderate magnitude and large epicentral distances. Because of this, the columns and braces are essential components of such structures and are built to withstand loads from wind and earthquakes.

Other constructions are not subject to the sloshing effects that occur when the fluid inside the tank exerts hydrodynamic force on the tank walls during seismic excitation.

It has been determined to implement the "Indian Institute of Technology, Kanpur-Gujarat State Disaster Management Act" because the Indian Standard (IS) code for seismic design does not have a provision on the seismic design of OWTs. (IITK-GSDMA 2007) guidelines for the seismic design of overhead liquid storage tanks (Moslemia et al. 2019).

Key Words: OWT (Overhead Water Tank), Earthquake, SAP 2000, Time history analysis, Displacement, Time periods, Base shear.

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