Effect of Container Height on Base Shear of Elevated Water Tank (original) (raw)
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Seismic Analysis of Cylindrical Liquid Storage Tank
Liquid storage tanks are used in industries for storing chemicals, petroleum products, and for storing water in public water distribution systems. Behaviour of Cylindrical liquid storage tanks under earthquake loads has been studied as per Draft code Part II of IS 1893:2002. A FEM based computer software (STAAD-PRO) used for seismic analysis of tanks which gives the earthquake induced forces on tank systems. Draft code Part II of IS 1893:2002 which will contain provisions for all types of liquid storage tanks. Under earthquake loads, a complicated pattern of stresses is generated in the tanks. Poorly designed tanks have leaked, buckled or even collapsed during earthquakes. Common modes of failure are wall buckling, sloshing damage to roof, inlet/outlet pipe breaks and implosion due to rapid loss of contents. In this research, a circular cylindrical elevated water tank, with 500 cubic meters capacity is analysed by using finite modelling techniques. This paper presents the study of seismic performance of the elevated water tanks for various heights and various seismic zones of India. The effect of height of water tank, earthquake zones on earthquake forces have been presented in this paper with the help of analysis of 20 models for same parameters. Analysis is carried out by using finite element software STAAD-PRO.
Seismic Performance of Circular Elevated Water Tank
International Journal of Science and Research (IJSR), 2015
Liquid storage tanks are used in industries for storing chemicals, petroleum products, and for storing water in public water distribution systems. Behaviour of Cylindrical liquid storage tanks under earthquake loads has been studied as per Draft code Part II of IS 1893:2002. A FEM based computer software (STAAD-PRO) used for seismic analysis of tanks which gives the earthquake induced forces on tank systems. Draft code Part II of IS 1893:2002 which will contain provisions for all types of liquid storage tanks. Under earthquake loads, a complicated pattern of stresses is generated in the tanks. Poorly designed tanks have leaked, buckled or even collapsed during earthquakes. Common modes of failure are wall buckling, sloshing damage to roof, inlet/outlet pipe breaks and implosion due to rapid loss of contents. Elevated water tanks should be competent of keeping the expected performance during and after earthquake. It has large mass concentrated at the top of slender supporting structure hence extremely vulnerable against horizontal forces due to earthquake. Staging is formed by a group of columns and horizontal braces provided at intermediate levels to reduce the effective length of the column. In this research, a circular cylindrical elevated water tank is analysed by using finite modelling techniques. This paper presents the study of seismic performance of the elevated water tanks for various heights and various seismic zones of India. The effect of height of water tank, earthquake zones on Nodal displacement have been presented in this paper with the help of analysis of 20 models for same parameters. Analysis is carried out by using finite element software STAAD-PRO.
Seismic Analysis of Liquid Storage Tanks
— Liquid storage tanks are used in industries for storing chemicals, petroleum products, and for storing water in public water distribution systems. Behavior of liquid storage tanks under earthquake loads has been studied as per Draft code Part II of IS 1893:2002. A FEM based computer software used (SAP 2000) for seismic analysis of tanks which gives the earthquake induced forces on tank systems. Indian seismic code IS 1893:1984 had some very limited provisions on seismic design of elevated tanks. This code did not cover ground-supported tanks. Draft code Part II of IS 1893:2002 which will contain provisions for all types of liquid storage tanks. Dynamic analysis of liquid containing tank is a complex problem involving fluid-structure interaction. Under earthquake loads, a complicated pattern of stresses is generated in the tanks. Poorly designed tanks have leaked, buckled or even collapsed during earthquakes. Common modes of failure are wall buckling, sloshing damage to roof, inlet/outlet pipe breaks and implosion due to rapid loss of contents. An example intz shape tank is analyzed as per the Draft code Part II of IS 1893:2002. This thesis consists of two different parts. In a first part, a theoretical point of view & formulations for analysis. The second part focuses on the model example to determine the seismic forces on tank.
As we know from past records, many of reinforced concrete elevated water tanks were heavily damages or collapsed during the earthquakes all over the world. General observations are pointing out the reasons towards the failure of supporting system which reveals that the supporting system of the elevated tanks has more critical importance than the other structural parts of tanks. Most of the damages observed during the seismic events arise was might be due to the lack of knowledge regarding the proper behaviour of supporting system of the tank against dynamic effect and also due to improper geometrical selection of staging patterns. The main objective of this study is to understand the behaviour of supporting system which is more effective under different earthquake characteristics or earthquake zones with STAAD. Pro V8i software. A sample of a reinforced concrete elevated water tank (Intz type), with 900 cubic meters and with a height of 18m from ground level is considered. Here two different staging patterns such as radial bracing and cross bracing are compared with basic supporting system for various fluid filling conditions. The seismic zones of Zone-III & Zone-V and the corresponding earthquake characteristics have been taken from IS 1893 (PART 1)-2002 & draft code IS 1893 (Part 2). Consequently the water mass has been considered in two parts as impulsive and convective suggested by GSDMA guidelines. Tank responses including base shear, overturning moment and roof displacement have been observed, and then the results have been compared and contrasted. The result shows that the structure responses are exceedingly influenced by the presence of water and the earthquake characteristics. Finally study discloses the importance of suitable staging configuration to remain withstands against heavy damage or failure of elevated water tank during seismic events.
Seismic Assessment of Elevated Circular Water Tank
The present study reports the analysis and design (Response Spectrum Analysis, Frequency Analysis and Time History Analysis) of an elevated circular water tank using STAAD.Pro V8i. The design involves load calculations manually and analysing the whole structure by STAAD.Pro V8i. The design method used in STAAD.Pro analysis is Limit State Design and the water tank is subjected to live load, dead load, self – weight and seismic loads. Seismic load calculations are done as per IS 1893-2000. Response Spectrum Analysis gives displacement, bending moment, shear force, axial force, and torsion values. Eigen solution so obtained helps in determining the base shear and various peak story shear values of the structure. Frequency analysis gives the natural frequency of the structure and time history, which defines the behaviour of the structure in certain interval of time against various functions like velocity, displacement and acceleration and hence the graphical solutions has been drawn for each analysis. Notations: 1. CPS = Cycles per second 2. D.L. = Dead Load 3. E.L. = Earthquake Load 4. f ck = Compressive Strength of Concrete (Mpa) 5. f y = Yield Stress of Steel (Mpa) 6. L.L. = Live Load 7. STAAD.Pro = Structural Analysis and Design for Professionals 1. Introduction and Background Storage tanks are built for storing water, liquid petroleum, petroleum products and similar liquids. Analysis and design of such tanks is independent of chemical nature of product. They are designed as crack free structures to eliminate any leakage. Adequate cover to reinforcement is necessary to prevent corrosion. In order to avoid leakage and to provide higher strength, concrete of grade M30 and above is recommended for liquid retaining structures. A new procedure to determine hydrodynamic pressures for rectangular tanks was discussed by Chen J.Z & Kianoush M.R [1] in which the effect of wall flexibility on impulsive pressures is considered and the behaviour of three types of open type tanks namely " shallow " , " medium " and " tall " , under seismic ground motions has been studied. For dynamic time history analysis Chen J.Z & Kianoush M.R [1] uses three suites of time history representing low, medium and high earthquake zones and while calculating the hydraulic pressure they assumed that the liquid storage tank is fixed to the rigid foundation and a Cartesian coordinate system has been used with origin located at the centre of the tank base. The motion of water relative to tank and motion of tank relative to ground was accounted by Housner G.W[2] which indicates a simplified dynamic analysis for the response of elevated water tanks to earthquake ground motion and it has also been pointed out that if a closed tank is completely full of water or completely empty, it is essentially a one-mass structure and if the tank has a freewater surface, there will be slashing of the water during an earthquake and this makes the tank essentially a two-mass structure. The earthquake performance of storage tanks in terms of earthquake resistance in Turkish industrial facilities was evaluated by Korkmaz K.A Et.Al [4] who believed that modelling a typical storage tank of an industrial
Looking back to past earthquakes shows seismic performance, destruction of liquid storage tanks regarding flat floor. Failure of these tanks causes human dire consequences, environmental and economical problems. Therefore, considering these destructions is of priorities. Since dynamic operation of tanks and researchers modelling in the past is the base of regulation design, so due to low thickness to the radius and length of cylindrical shells is prone to buckling. In this survey, with dynamic analysing of steel tanks we investigated the vibration behaviour of water and structure in an uninhibited manner regarding different water height ratios. To do this, a cylindrical tank is modelling using finite element analysis with ANSYS software. To model liquidshell system in shell part we use finite element analysis and liquid surrounding by added mass analysis. Comparing with regulations, the findings will be investigated with static analysis and the most critical result for tension and movement will be presented in dynamic analysis. In the following compare seismic performance of uninhibited tanks using added mass analysis and the results present in diagrams and tables.
RESPONSE OF ELEVATED WATER STORAGE TANKS UNDER SEISMIC EVENTS
IRJET, 2022
The current analysis and designs of elevated overhead tanks are extremely weak under adjacent forces due to an earthquake zone. In the past earthquakes, it has ensued found that the reinforced concrete elevated overhead tanks under lateral earthquake loads were suspectable where in some cases the structure has experienced collapse. Whereas the water works as an important role in the dayto-day life of a human being the elevated tanks should be designed as per the code provisions so that to avoid the failures of the structure and for the life of the structure. The study and creation of the elevated overhead tanks are done in ETABS software according to Indian Standards Codes. The reinforced concrete elevated water storage tank and the steel elevated water storage tanks have been designed for a full tank condition and the response spectrum plots and the time-history plots are also generated along with displacements & drifts. The columns and beams of the reinforced concrete storage tank are designed in accordance with IS456:2000 and the steel water tank is designed in accordance with IS800:2007. The designed structure is analyzed to check the reaction of the structure under the seismic events and the time history analysis is also being analyzed from the previous records.
REVIEW ON SEISMIC ANALYSIS OF ELEVATED WATER TANK-2
Elevated Water Tanks are one of the most important lifeline structures in the earthquake regions. In major cities and also in rural areas elevated water tanks forms an integral part of water supply scheme. The elevated water tanks must remain functional even after the earthquakes as water tanks are required to provide water for drinking and firefighting purpose. These structures has large mass concentrated at the top of slender supporting structure hence these structure are especially vulnerable to horizontal forces due to earthquakes. All over the word, the elevated water tanks were collapsed or heavily damaged during the earthquakes because of unsuitable design of supporting system or wrong selection of supporting system and underestimated demand or overestimated strength. So, it is very important to select proper supporting system and also need to study the response of Elevated Water Tanks to dynamic forces by both equivalent Static method as well as Dynamic method and to find out the design parameters for seismic analysis. It is also necessary to consider the sloshing effect on container roof slab. This sloshing of water considerably differ the parametric values used in design and economy of construction. The effect of hydrodynamic pressure must be considered in the seismic analysis of Elevated Water Tank.
A STUDY ON THE SEISMIC RESPONSE OF ELEVATED WATER TANK
IRJET, 2022
Water tanks have been the most vital lifeline structures. They serve as an essential component for most water supply schemes in urban and rural areas. Water storage is generally based on overhead water tanks since the required pressure in the water delivery process is achieved by gravity in elevated tanks rather than the need for large pumping systems. These elevated tanks consist of a large water mass at the top supported by a tall staging which is extremely weak against horizontal forces caused due to earthquakes. The selection of a suitable staging system plays a major role in the behaviour of elevated water tanks during earthquakes since these tanks are often utilized in seismically active regions. The ductility and energy absorbing capacity of such elevated tanks are less compared to conventional building and hence seismic safety of such structures are very important. Soil-structure interaction (SSI) is one of the most essential components of structural analysis. This interaction can change the Dynamic characteristics of a structure, which can be advantageous or detrimental to its performance. Conventional fixed base analysis disregards the effect of soil flexibility, resulting in an unsafe design. The present work is focused on the study of seismic response of elevated water tank considering the sloshing effect and to evaluate the behaviour considering Soil-Structure Interaction (SSI) effect in seismic Zone (II and III). Different soil conditions are also adopted as per IS1893(Part 2):2014. Modelling and analysis has been carried out using FEM based software SAP2000.