International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395 -0056
Volume: 04 Issue: 04 | Apr -2017
p-ISSN: 2395-0072
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REVIEW ON STRUCTURAL PERFORMANCE OF WATER TANKS UNDER DYNAMIC LOADING Shilja Sureshkumar1, Asha Joseph2 1PG
Student, Department of Civil Engineering, FISAT, Angamaly, India Professor, Department of Civil Engineering, FISAT, Angamaly, India ---------------------------------------------------------------------***--------------------------------------------------------------------2Assistant
Abstract - Liquid storage tanks are used to store different type of materials such as water, oil and gas etc. Damaged tanks containing any hazardous material causes environmental pollution. Failure of water tanks results very destructive hazards on life and property. Seismic study of water tanks are essential for strengthening the tank’s performance and thereby damages can be reduced. Seismic analysis of water tanks are much complicated due the fluid structure interaction of the system. Fluid inside the tank are divided as impulsive and convective liquid mass, and both are induced hydrodynamic pressure on tank wall and base. Seismic energy is transferred to the fluid from ground due to movement of tanks. Soil structure interaction is another parameter which significantly effect on tank’s performance. Interaction of tank with surrounding soil structure will be different, based on soil properties such as elastic properties, cohesion, angle of friction etc. Response of elevated tanks and ground supported tanks are different, based on their support conditions provided. Container height, geometry, soil denseness, types of foundation, damping parameters are some of the factors influencing tank response under different types of loadings. Variations in the structural performance of water tanks due to these factors are discussed in this paper based on various literatures studies.
sloshing motion. This mass is termed as convective liquid mass and it exerts convective hydrodynamic pressure. Housner developed a spring mass model system for representing tank and fluid interaction. In spring mass model of tank-liquid system, these two liquid masses are to be suitably represented and parameters of this model depends on geometry of the tank and its flexibility. In early studies of tanks on its seismic response liquid and the tank together is considered as rigid body and attention was focused only on dynamic response of tank’s liquid content. After some earthquakes such as Niigata, (1964); Alaska, 1964: and Park field, (1966); which caused severe damage to liquid storage tanks; it was observed that rigid tank concept for modelling of tank could not be adopted for analysis of the tanks. Interaction between the tank wall and the liquid inside the tank has to be taken in the seismic analysis of liquid storage tanks since the tanks itself deform under earthquake loads. Seismic analysis of liquid storage tank is complicated due to the complicated fluid structure interaction (FSI) of the system. From engineer’s point of view storage tanks should maintain sufficient strength and resist all the forces acting on the tank with much safety. The past earthquakes studies shows that it is very necessary to study seismic response of water tanks.
Key Words: Fluid structure interaction, Soil structure interaction, Sloshing, Seismic response, Impulsive and Convective liquid mass,
Liquid storage tanks involve various types of failure mechanisms. Some of them are shell buckling, sloshing damages, support failure, base sliding etc. Past observations of the seismic performances of the liquid storage tanks have revealed that storage tanks failures are manifested in a wide variety of ways. Different failure mechanisms are possible, depending upon the configuration of tank geometry, possible fluid-structure-soil interaction, and a lot of other factors such as the tank material, type of support structure, etc. On the other hand, characteristics of earthquakes are also significantly influence the dynamic response of liquid storage tanks. Failure modes of rectangular tank are significantly different from those of cylindrical, spherical, and conical tanks. Similarly, the failure patterns for rigid tanks considerably differ from those for flexible tanks. Different combinations of above possible parameters make the failure mechanism more complex.
1. INTRODUCTION The forces due to earthquakes and sloshing of fluid inside the tanks are important considerations in the design of civil engineering structures. Seismic safety of liquid-filled container is of great concern because of the potential adverse of economic and environmental impacts associated with failure of the containers and liquid spillage on the surrounding area. As a result, a considerable amount of research effort has been devoted for a better determination of the seismic behavior of liquid tanks and the improvement of associated design codes. In a liquid storage tanks, liquid in the lower region of the tank behaves as a liquid mass that is rigidly connected to tank wall. This mass is termed as impulsive liquid mass which accelerates along with the wall and induced impulsive hydrodynamic pressure on tank wall and tank base. Liquid mass in upper region of the tank undergo
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