Analysis and structural behavior of cylindrical steel tanks under seismic effects (original) (raw)

SEISMIC RESPONSE OF LARGE CYLINDRICAL TANKS FOR OIL STORAGE WITH FLEXIBLE WALLS

First European Conference on Earthquake Engineering and Seismology

In Mexico, PEMEX manage different terminals of storage of oil in all country. Therefore, structural integrity of the aboveground storage tanks must be carefully assessed. Consequently, the storage tanks have been placed in high seismic risk areas. As a result, this research has focused on the behaviour and seismic response of already existing steel storage tanks of large capacity of 500, 200, 150, 100 and 55 thousands barrels, located in high risk zones.

Fem Seismic Analysis of Steel Tanks for Oil Storage in Industrial Facilities

14 th World Conference on …, 2008

Structural and seismic engineering are involved in the design of new industrial facilities, but have certainly a primary role in the evaluation and upgrading of existing plants. Atmospheric steel tanks for oil and other hazardous material storage are commonly used in power plants, airports, and other critical plants. Their design is somehow very standardized worldwide and thus they represent a challenging topic in the context of an industrial risk assessment related to external hazards like earthquakes. In fact, their dynamic response is not trivial, since fluid/structure interactions are relevant and influence the susceptibility to seismic damage. A full stress analysis is certainly the more accurate way to design and to evaluate the risk of steel tanks under earthquake loads, but is generally demanding in terms of computational effort. This approach leads to the direct computation of the interaction between shell deformations and content motion during earthquakes. In the present paper, seismic evaluation according to Eurocode 8 is discussed and some global results of Finite Element Analyses (FEM) analyses are compared with those obtained according to simplified design procedures by Eurocode 8.

Seismic Design Evaluation of Liquid-Filled Stiffened Steel Cylindrical Tanks

Proceedings of International Structural Engineering and Construction, 2019

This paper aims to estimate dynamic buckling loads of cylindrical liquid storage tanks. Finite element analysis is performed using ANSYS computer program. Twelve different geometries of the cylindrical tanks are analyzed with height to diameter (H/D) ratios of 0.5, 1.0, 1.5, and 2.0 and the diameter to thickness (D/t) ratios of 1000, 1500, and 2000 to cover tall and short cylindrical tanks. The dynamic buckling capacities of cylindrical tanks filled with water up to 90% of their height are investigated in this study. The transient dynamic analysis is performed to find the dynamic buckling loads. Applied dynamic loads in this study are horizontal earthquake excitations in terms of acceleration (g) due to gravity. The transient dynamic analysis results indicate that the dynamic buckling loads decrease when the H/D ratios increase, and the dynamic buckling loads decrease when the D/t ratios increase. Design curves for the cylindrical tanks of various geometries subjected to earthquake ...

SEISMIC ANALYSIS OF STEEL STORAGE TANKS: OVERVIEW OF DESIGN CODES USED IN PRACTICE

Seismic provision of all types of structures is of paramount importance in regions defined by medium and high seismic hazard. This is all the more true in the case of steel storage tanks, as these often contain toxic, flammable and explosive substances or the fuels needed for post-state recovery after a catastrophic event. Additionally, steel storage tanks could be an integral part of special facilities related to national security and defence. The current paper presents an overview of the European design codes used in practice regarding the analysis, behaviour and design of steel tanks under earthquake loading, namely EN 1998-4 (BDS EN 1998-4:2006, along with the national annex BDS EN 1998-4:2006/NA:2012) and EN 14015 (BDS EN 14015:2005). Other legislative documents-API Standard 650 and API Standard 620 are also considered. The aim of the paper is to compare the provisions provided by the aforementioned documents focusing on the aspects that require further investigation and regulation, as well as those not dealt with in the regulatory framework. Special attention is paid to the effects that a seismic event would have on the stationary roofs of vertical cylindrical steel storage tanks.

Seismic Analysis of Perfect and Imperfect Cylindrical Liquid Storage Tanks

International Journal of Civil Infrastructure, 2021

This paper presents the behaviour and design guidelines of cylindrical steel liquid storage tanks subjected to various strong earthquake excitations. The authors aim to develop practical design equations and charts estimating the buckling strength of the cylindrical steel liquid-filled tanks subjected to seismic loads. Numerical analysis is used to evaluate the buckling strength of cylindrical steel liquid-filled tanks. Finite element analysis is performed using the commercial computer program ANSYS. Both geometrically perfect and imperfect tanks are studied. The modelling method, appropriate element type, and the necessary number of elements to use in numerical analysis are recommended. The main phenomena addressed in this paper include pre-and postbuckling strength of the tanks. Field observations during past earthquakes together with finite element analyses and published experimental results are used to substantiate the accuracy of employed finite element analysis. Based on the extensive parametric study the accuracy of the current design guidelines is assessed. According to the results of the parametric study of the perfect tanks, the buckling strength decreases significantly as the diameter-to-thickness ratio (D/t) increases, while it decreases slightly as the height-to-diameter ratio (H/D) increases. The buckling strength of the tanks decreases significantly as the amplitude of initial geometric imperfection increases. Design equations and design curves for the cylindrical steel liquid-filled tanks of various geometries subjected to different earthquakes are proposed and presented.

Heuristic optimization of cylindrical thin-walled steel tanks under seismic loads

Thin-Walled Structures, 2013

Cylindrical ground supported steel tanks are traditionally applied to store water and inflammable liquids due to their simple structural design, very good behavior under hydrostatic loads, low cost and easy construction. Despite these advantages, thin-walled steel tanks are sensitive to seismic loading. The aim of this work is the simplified, fast and direct optimum seismic design of these special structures, avoiding complicated computational methods such as the finite element or the boundary element methods. This objective is achieved using software developed in-house, where the optimum seismic design is achieved satisfying the stability of these structures under extreme seismic design loads according to the Eurocode 8 or the Greek seismic regulation provisions. The proposed method provides with the most economical dimensions for the tank and its foundation, for a predefined, design liquid volume. The proposed method can be considered as a basis for determining minimum cost seismic design of thin-walled steel tanks that satisfy the structural and stability requirements.

DYNAMIC BUCKLING OF CYLINDRICAL STORAGE TANKS DURING EARTHQUAKE EXCITATIONS

The behavior of storage tanks' analysis in seismic areas is of major importance because of the strategic nature of these works. The steel cylindrical tanks are the most susceptible to damage due to dynamic buckling during earthquakes. In this study, three criteria are used to estimate the critical peak ground acceleration caused the tank instability. The liquid inside the tank was modeled using specific Ansys's finite elements and fluid-structure interaction. The calculation includes modal and time history analysis, including material and geometric non-linearity. The result values are compared with standard code previsions as well as the results of previous numerical research, and show the need to improve code provisions.

Design Peculiarities of Oil Storage Tanks in Complex Geotechnical Conditions at Seismic Effects

Zbìrnik naukovih pracʹ, 2017

Problematic issues of construction and operation of oil storage vertical steel tanks in complex geotechnical conditions, including the seismically unstable territories are systematized. The technique of seismic danger decreasing (increasing the seismic stability of the ground) for ensuring the accident-free operation of tanks during earthquakes of various intensities is proved. The practical experience of design solutions of the highly effective systems «man-made grounds-foundation-tank» in complex geotechnical conditions for static and dynamic effects (earthquakes, emergency technogenic loadings, etc.) is given.