Discrete Models for Seismic Analysis of Liquid Storage Tanks of Arbitrary Shape and Fill Height

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
G. C. Drosos ◽  
A. A. Dimas ◽  
D. L. Karabalis
Keyword(s):  
Arbitrary Shape ◽  
Seismic Analysis ◽  
Fluid Motion ◽  
Discrete Models ◽  
Storage Tanks ◽  
Fem Modeling ◽  
Liquid Mass ◽  
Liquid Storage ◽  
Conical Tanks ◽  
Cylindrical Tanks

A finite element method (FEM)-based formulation is developed for an effective computation of the eigenmode frequencies, the decomposition of total liquid mass into impulsive and convective parts, and the distribution of wall pressures due to sloshing in liquid storage tanks of arbitrary shape and fill height. The fluid motion is considered to be inviscid (slip wall condition) and linear (small free-surface steepness). The natural modal frequencies and shapes of the sloshing modes are computed, as a function of the tank fill height, on the basis of a conventional FEM modeling. These results form the basis for a convective-impulsive decomposition of the total liquid mass, at any fill height, for the first few (two or three at most) sloshing modes, which are by far the most important ones in comparison to all other higher modes. This results into a simple yet accurate and robust model of discrete masses and springs for the sloshing behavior. The methodology is validated through comparison studies involving vertical cylindrical tanks. Additionally, the application of the proposed methodology to conical tanks and to the seismic analysis of spherical tanks on a rigid or flexible supporting system is demonstrated and the results are compared to those obtained by rigorous FEM analyses.

Seismic analysis of base-isolated liquid storage tanks using the BE–FE–BE coupling technique

2002 ◽  
Vol 22 (9-12) ◽  
pp. 1151-1158 ◽  
Author(s):  
Moon Kyum Kim ◽  
Yun Mook Lim ◽  
Seong Yong Cho ◽  
Kyung Hwan Cho ◽  
Kang Won Lee
Keyword(s):  
Seismic Analysis ◽  
Storage Tanks ◽  
Coupling Technique ◽  
Liquid Storage

Parametric study of stochastic seismic responses of base-isolated liquid storage tanks under near-fault and far-fault ground motions

2016 ◽  
Vol 24 (24) ◽  
pp. 5747-5764 ◽  
Author(s):  
Sina Safari ◽  
Reza Tarinejad
Keyword(s):  
Base Isolation ◽  
Seismic Analysis ◽  
Ground Motions ◽  
Characteristic Parameter ◽  
Statistical Linearization ◽  
Storage Tanks ◽  
Earthquake Excitation ◽  
Isolation System ◽  
Near Fault ◽  
Liquid Storage

Seismic response of base isolated steel liquid storage tanks is investigated in this study by a stochastic approach in frequency domain. For the purpose of evaluating different frequency contents of seismic events on the responses of fixed and isolated tanks, the earthquake excitation is characterized by power spectral density function. Since earthquake is a random process, stochastic seismic analysis is used and root mean square response predicts behavior of system properly. Two types of isolation system are assumed and nonlinear behavior of base isolation systems are developed by an iterative statistical linearization scheme. The study demonstrates the influence of each characteristic parameter of the storage tanks and isolation system and also excitation features. It is confirmed that near-fault earthquake excitations amplify the overall response of the system. Base isolation is known as an effective technique to reduce responses appropriately. It is demonstrated that the sloshing responses of the tanks is significantly reduced by sliding bearing. Further, excitation parameters, PGV/PGA ratio of records and pulse period in near-fault ground motions, that represent differences in two sets of earthquakes are defined to recognize variation of responses.

Seismic analysis of liquid storage composite conical tanks

2018 ◽  
Vol 159 ◽  
pp. 128-140
Author(s):  
Ahmed A. Elansary ◽  
Ashraf A. El Damatty
Keyword(s):  
Seismic Analysis ◽  
Liquid Storage ◽  
Conical Tanks

scholarly journals Simple Procedure for Seismic Analysis of Liquid-Storage Tanks

2000 ◽  
Vol 10 (3) ◽  
pp. 197-201 ◽  
Author(s):  
Praveen K. Malhotra ◽  
Thomas Wenk ◽  
Martin Wieland
Keyword(s):  
Seismic Analysis ◽  
Simple Procedure ◽  
Storage Tanks ◽  
Liquid Storage

Simplified Model for the Seismic Performance of Unanchored Liquid Storage Tanks

2015 ◽  
Author(s):  
Maria Vathi ◽  
Spyros A. Karamanos
Keyword(s):  
Bottom Plate ◽  
Storage Tanks ◽  
Mass System ◽  
Aspect Ratios ◽  
Liquid Storage ◽  
Stress And Deformation ◽  
Cylindrical Tanks ◽  
Welded Connection ◽  
Simplified Modeling ◽  
Different Levels

Ground-supported unanchored liquid-storage cylindrical tanks, when subjected to strong seismic loading may exhibit uplifting of their bottom plate, which has significant effects on their dynamic behavior and strength. Those effects mainly concern: (a) the increase of axial (meridional) compression at the tank base, resulting in premature buckling in the form of elephant’s foot and (b) the significant plastic deformation at the vicinity of the welded connection between the tank shell and the bottom plate that may cause failure of the welded connection due to fracture and fatigue. The present study focuses on base uplifting mechanics and tank performance with respect to the shell/plate welded connection through a numerical two-step methodology: (1) a detailed finite element shell model of the tank for incremental static analysis, capable of describing the state of stress and deformation at different levels of loading and (2) a simplified modeling of the tank as a spring-mass system for dynamic analysis, enhanced by a nonlinear spring at its base to account for the effects of uplifting. Two cylindrical liquid storage tanks of different aspect ratios are modeled and analyzed in terms of local performance of the welded connection. The results are aimed at better understanding of tank uplifting mechanics and motivating possible amendments in existing seismic design provisions.

Nonlinear behaviour of bottom plate in cylindrical liquid storage tanks for seismic applications

1995 ◽  
Vol 22 (1) ◽  
pp. 180-189 ◽  
Author(s):  
David T. Lau ◽  
Xianguang Zeng
Keyword(s):  
Bottom Plate ◽  
Response Analysis ◽  
Beam Model ◽  
Nonlinear Behaviour ◽  
Storage Tanks ◽  
One Dimensional ◽  
Nonlinear Springs ◽  
Liquid Storage ◽  
Cylindrical Tanks ◽  
Seismic Applications

The paper presents a simplified pseudostatic approach to model the nonlinear behaviour of the bottom plate in unanchored cylindrical liquid storage tanks for seismic applications. In this paper, the problem of axisymmetric uplift of the bottom plate is studied for tanks supported on both rigid and elastic Winkler foundations. In the analysis, the bottom plate is modelled by one-dimensional beam and two-dimensional plate models. By comparing the results, it is found that the one-dimensional beam model gives accurate results acceptable for all practical design purposes, in view of the many other uncertainties in the tank uplift problem. The analysis results also show that the support foundation flexibility may have significant effects on the uplift behaviour of the tanks. Based on the axisymmetric uplift results, the paper then presents a simple approach to model the seismic partial uplift problem of unanchored tanks by means of nonlinear springs. Modelling parameters for the nonlinear springs are generated for dynamic uplift response analysis. Sensitivities of the uplift behaviour and the nonlinear spring modelling parameters to the tank height-to-radius ratio and the soil stiffness are also studied. Key words: axisymmetric uplift, cylindrical tanks, earthquakes, pressure vessel, shell, soil effect.

scholarly journals Buckling of thin-walled cylinders: experimental and numerical investigation

2010 ◽  
pp. 47-52
Author(s):  
Caitríona de Paor
Keyword(s):  
Chemical Engineering ◽  
Oil And Gas ◽  
High Strength ◽  
External Pressure ◽  
Storage Tanks ◽  
Diverse Range ◽  
Thin Walled Structures ◽  
Liquid Storage ◽  
Thin Walled ◽  
Cylindrical Tanks

Thin-walled structures, also known as shells, combine light weight with high strength and are used in a diverse range of fields including aerospace engineering, civil engineering and chemical engineering. Common applications of these shells include oil and gas storage tanks, powder or liquid storage tanks in pharmaceutical plants as well as airplane frames and ship bodies. Although these thin-walled shells have a wide variety of uses, this research is motivated by storage tank collapse in the process industry. Thin-walled cylindrical tanks common in the food and biotechnology sectors are prone to buckling (or inward collapse) due to accidentally induced internal vacuum. During the sterilisation process, steam can condense, causing a reduction in volume. This results in an equivalent increase in external pressure, triggering collapse, or buckling of the tank. Such a collapse, if it occurs, tends to be catastrophic resulting in the complete destruction of the vessel (see Fig.1). Notwithstanding ...

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