Elephant Foot Buckling Analysis of Large Unanchored Oil Storage Tanks With Tapered Shells Subjected to Foundation Settlement

2020 ◽  
Author(s):  
Lei Shi ◽  
Xiaolin Wang ◽  
Liang Chang ◽  
Xue Li
Keyword(s):  
Finite Element ◽  
Numerical Study ◽  
Plastic Material ◽  
Element Model ◽  
Nonlinear Boundary Conditions ◽  
Storage Tanks ◽  
Nonlinear Stabilization ◽  
Buckling Strength ◽  
Oil Storage ◽  
Steel Tank

Abstract This paper presents an numerical study on a large unanchored open-topped steel tank. The buckling behaviors of the tank are analyzed using the finite element computer package ANSYS by means of nonlinear stabilization algorithm. The effects of foundation harmonic settlement on the elephant foot buckling strength of large unanchored open-topped oil storage tanks with tapered shells under axial compression are explored by numerical modeling. Various items of actual geometrical structure which involve concrete ringwall foundation of tank, unanchored bottom with slope, shell tapering from the base to the top, wind girders and supports, top angles, stiffening rings and support plates are presented thoroughly in the non-symmetrical 3D finite element model. Geometric nonlinearity, nonlinear boundary conditions and elastic plastic material of Ramberg-Osgood model are involved simultaneously in simulate course. The obtained solutions are displayed graphically for selected values of system parameters: harmonic settlement amplitude, harmonic number, and critical buckling stress of axially compressed oil tank. The results will provide insights into the relationship between foundation harmonic settlement and buckling strength of the large cylinders.

Numerical Study of Oil Storage Tanks during Planar Settlement

2018 ◽  
Vol 878 ◽  
pp. 95-103
Author(s):  
Joko Wisnugroho ◽  
Sutomo
Keyword(s):  
Finite Element ◽  
Storage Tank ◽  
Numerical Study ◽  
Plate Thickness ◽  
Element Model ◽  
American Petroleum Institute ◽  
Seismic Zone ◽  
Storage Tanks ◽  
Oil Storage ◽  
Oil Storage Tank

Inspection and maintenance are necessary to maintain the continuity of critical equipment operations such as oil storage tank. The criteria for the various types of settlement specified in American Petroleum Institute (API) 653. However, the criteria for planar settlement could not be determined. In this paper, a finite element model is developed to study the hoop stress of the tank during planar settlement. In this paper, 384 finite element models were built in order to predict the most effective allowable planar settlement at oil storage tanks. Each model is variation of the tank size, shell plate thickness, seismic zone and planar tilt of the tank. Based on size of tank population in Pertamina, 8 of standard tank size from 500-10.000 m3 were simulated. The simulation results are validated by case study in 500-5.000 m3 full scale oil storage tank. From the results, equation for criteria of planar settlement has been created.

Oil Storage Tank Settlement Assessment Based on Standard and Finite Element Analyses

2017 ◽  
Author(s):  
Lei Shi ◽  
Xiaolin Wang ◽  
Jian Shuai ◽  
Kui Xu ◽  
Ming Li
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Storage Tank ◽  
Large Scale ◽  
Element Model ◽  
Foundation Settlement ◽  
Storage Tanks ◽  
Strength Assessment ◽  
Oil Storage ◽  
Oil Storage Tank

It is well known that foundation settlement of tank is particularly severe, and can produce distortion and stress of the tank, especially differential settlement around the circumference of the foundation below the shell of large-volume tank. The settlement standards involving European EEMUA 159-2003, American API 653-2009, and Chinese codes SH/T 3123-2001, SY/T 5921-2011 for in-service assessment of large-scale storage tank were reviewed and discussed. Finite element model for strength assessment of large-scale oil storage tank was developed based on actual field data of tank foundation settlement. The whole stress distributions and deformation of seven large-scale oil storage tanks in a depot in China were analyzed under the conditions of the practical pressure test through finite-element method. It also provides a comparison between an analytical model based on settlement criteria and a finite element model that replicates field operating loading and settlement conditions of storage tanks. A basis for comparison between models was established from the maximum allowable settlement and stress values. It was found that results from settlement standards of tank in China and other countries were more conservative than those from FEA, and SY/T 5921 in China made most stringent requirements for the tank settlement. The evaluation indicators of differential foundation settlement around the tank circumference are unreasonable in standards and rules mentioned above, the structural response of tank such as stress and deformation under foundation settlement should be considered sufficiently.

scholarly journals A Numerical Study of the Stiffness and Strength of Cross-Laminated Timber Wall-to-Floor Connections under Compression Perpendicular to the Grain

Buildings ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 442
Author(s):  
Shaheda T. Akter ◽  
Michael Schweigler ◽  
Erik Serrano ◽  
Thomas K. Bader
Keyword(s):  
Finite Element ◽  
Annual Ring ◽  
Numerical Study ◽  
Plastic Material ◽  
Element Model ◽  
Material Behavior ◽  
Thickness Effect ◽  
Parameter Study ◽  
Regression Equations ◽  
Cross Laminated Timber

The use of cross-laminated timber (CLT) in multi-story buildings is increasing due to the potential of wood to reduce green house gas emissions and the high load-bearing capacity of CLT. Compression perpendicular to the grain (CPG) in CLT is an important design aspect, especially in multi-storied platform-type CLT buildings, where CPG stress develops in CLT floors due to loads from the roof or from upper floors. Here, CPG of CLT wall-to-floor connections are studied by means of finite element modeling with elasto-plastic material behavior based on a previously validated Quadratic multi-surface (QMS) failure criterion. Model predictions were first compared with experiments on CLT connections, before the model was used in a parameter study, to investigate the influence of wall and floor thicknesses, the annual ring pattern of the boards and the number of layers in the CLT elements. The finite element model agreed well with experimental findings. Connection stiffness was overestimated, while the strength was only slightly underestimated. The parameter study revealed that the wall thickness effect on the stiffness and strength of the connection was strongest for the practically most relevant wall thicknesses between 80 and about 160 mm. It also showed that an increasing floor thickness leads to higher stiffness and strength, due to the load dispersion effect. The increase was found to be stronger for smaller wall thicknesses. The influence of the annual ring orientation, or the pith location, was assessed as well and showed that boards cut closer to the pith yielded lower stiffness and strength. The findings of the parameter study were fitted with regression equations. Finally, a dimensionless ratio of the wall-to-floor thickness was used for deriving regression equations for stiffness and strength, as well as for load and stiffness increase factors, which could be used for the engineering design of CLT connections.

Elasto-Plastic Coupled Temperature-Displacement Finite Element Analysis of Two-Dimensional Rolling-Sliding Contact With a Translating Heat Source

1991 ◽  
Vol 113 (1) ◽  
pp. 93-101 ◽  
Author(s):  
S. M. Kulkarni ◽  
C. A. Rubin ◽  
G. T. Hahn
Keyword(s):  
Finite Element ◽  
Half Space ◽  
Plastic Material ◽  
Element Model ◽  
Rolling Contact ◽  
Two Dimensional ◽  
Element Analysis ◽  
Element Mesh ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic

The present paper, describes a transient translating elasto-plastic thermo-mechanical finite element model to study 2-D frictional rolling contact. Frictional two-dimensional contact is simulated by repeatedly translating a non-uniform thermo-mechanical distribution across the surface of an elasto-plastic half space. The half space is represented by a two dimensional finite element mesh with appropriate boundaries. Calculations are for an elastic-perfectly plastic material and the selected thermo-physical properties are assumed to be temperature independent. The paper presents temperature variations, stress and plastic strain distributions and deformations. Residual tensile stresses are observed. The magnitude and depth of these stresses depends on 1) the temperature gradients and 2) the magnitudes of the normal and tangential tractions.

Numerical Study for Global Detection of Cracks Embedded in Beams

1999 ◽  
Author(s):  
S. A. Lipsey ◽  
Y. W. Kwon
Keyword(s):  
Finite Element ◽  
Dynamic Analysis ◽  
Natural Frequency ◽  
Mode Shape ◽  
Numerical Study ◽  
Element Model ◽  
Mode Shapes ◽  
Linear Effect ◽  
Modes Of Vibration ◽  
Damage Simulation

Abstract Damage reduces the flexural stiffness of a structure, thereby altering its dynamic response, specifically the natural frequency, damping values, and the mode shapes associated with each natural frequency. Considerable effort has been put into obtaining a correlation between the changes in these parameters and the location and amount of the damage in beam structures. Most numerical research employed elements with reduced beam dimensions or material properties such as modulus of elasticity to simulate damage in the beam. This approach to damage simulation neglects the non-linear effect that a crack has on the different modes of vibration and their corresponding natural frequencies. In this paper, finite element modeling techniques are utilized to directly represent an embedded crack. The results of the dynamic analysis are then compared to the results of the dynamic analysis of the reduced modulus finite element model. Different modal parameters including both mode shape displacement and mode shape curvature are investigated to determine the most sensitive indicator of damage and its location.

Étude de la réouverture de la lagune du Havre aux Basques. I. Modélisation numérique des conditions d'écoulement

1995 ◽  
Vol 22 (1) ◽  
pp. 55-71
Author(s):  
Y. Ouellet ◽  
A. Khelifa ◽  
J.-F. Bellemare
Keyword(s):  
Finite Element ◽  
Numerical Study ◽  
Element Model ◽  
Two Dimensional ◽  
Flow Conditions ◽  
Modélisation Numérique ◽  
Tidal Flows ◽  
Dimensional Finite Element ◽  
The Stability ◽  
La Madeleine

A numerical study based on a two-dimensional finite element model has been conducted to analyze flow conditions associated with different possible designs for the reopening of Havre aux Basques lagoon, located in Îles de la Madeleine, in the middle of the Gulf of St. Lawrence. More specifically, the study has been done to better define the depth and geometry of the future channel as well as its orientation with regard to tidal flows within the inlet and the lagoon. Results obtained from the model have been compared and analyzed to put forward some recommendations about choice of a design insuring the stability of the inlet with tidal flows. Key words: numerical model, finite element, lagoon, reopening, Havre aux Basques, Îles de la Madeleine.

scholarly journals Modeling inflatable fabric with undevelopable surfaces by motion folding method

2019 ◽  
Vol 14 ◽  
pp. 155892501988640
Author(s):  
Xiao-Shun Zhao ◽  
He Jia ◽  
Zhihong Sun ◽  
Li Yu
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Numerical Study ◽  
Technical Problem ◽  
Three Dimensional ◽  
Element Model ◽  
Model Errors ◽  
Folding Model ◽  
Study Results ◽  
The Stability

At present, most space inflatable structures are composed of flexible inflatable fabrics with complex undevelopable surfaces. It is difficult to establish a multi-dimensional folding model for this type of structure. To solve this key technical problem, the motion folding method is proposed in this study. First, a finite element model with an original three-dimensional surface was flattened with a fluid structure interaction algorithm. Second, the flattened surface was folded based on the prescribed motion of the node groups, and the final folding model was obtained. The fold modeling process of this methodology was consistent with the actual folding processes. Because the mapping relationship between the original finite element model and the final folding model was unchanged, the initial stress was used to modify the model errors during folding process of motion folding method. The folding model of an inflatable aerodynamic decelerator, which could not be established using existing folding methods, was established by using motion folding method. The folding model of the inflatable aerodynamic decelerator showed that the motion folding method could achieve multi-dimensional folding and a high spatial compression rate. The stability and regularity of the inflatable aerodynamic decelerator numerical inflation process and the consistency of the inflated and design shapes indicated the reliability, applicability, and feasibility of the motion folding method. The study results could provide a reference for modeling complex inflatable fabrics and promote the numerical study of inflatable fabrics.

Numerical Study of Welding Sequence on the Residual Stress Field in a Thick-Walled Tee Joint

2011 ◽  
Vol 219-220 ◽  
pp. 1211-1214
Author(s):  
Wei Jiang
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Numerical Study ◽  
Three Dimensional ◽  
Element Model ◽  
Residual Stress Field ◽  
Factors Affecting ◽  
Welding Sequence ◽  
Welding Sequences ◽  
Three Dimensional Finite Element

Finite element simulation is an efficient method for studying factors affecting weld-induced residual stress distributions. In this paper, a validated three-dimensional finite element model consisting of sequentially coupled thermal and structural analyses was developed. Three possible symmetrical welding sequences, i.e. one-welder, two-welder and four-welder sequence, which were perceived to generate the least distortion in actual welding circumstances, were proposed and their influences on the residual stress fields in a thick-walled tee joint were investigated. Appropriate conclusions and recommendations regarding welding sequences are presented.

A Method for FE Model Updating of Coupled Vibro-Acoustic Systems Using Constrained Optimization

2013 ◽  
Author(s):  
D. V. Nehete ◽  
S. V. Modak ◽  
K. Gupta
Keyword(s):  
Finite Element ◽  
Constrained Optimization ◽  
Model Updating ◽  
Numerical Study ◽  
Element Model ◽  
Rectangular Cavity ◽  
Mode Shapes ◽  
Fe Model ◽  
Structural Dynamic ◽  
Fe Model Updating

Finite element (FE) model updating is now recognized as an effective approach to reduce modeling inaccuracies present in an FE model. FE model updating has been researched and studied well for updating FE models of purely structural dynamic systems. However there exists another class of systems known as vibro-acoustics in which acoustic response is generated in a medium due to the vibration of enclosing structure. Such systems are commonly found in aerospace, automotive and other transportation applications. Vibro-acoustic FE modeling is essential for sound acoustic design of these systems. Vibro-acoustic system, in contrast to purely structural system, has not received sufficient attention from FE model updating perspective and hence forms the topic of present paper. In the present paper, a method for finite element model updating of coupled structural acoustic model, constituted as a problem of constrained optimization, is proposed. An objective function quantifying error in the coupled natural frequencies and mode shapes is minimized to estimate the chosen uncertain parameters of the system. The effectiveness of the proposed method is validated through a numerical study on a 3D rectangular cavity attached to a flexible panel. The material property and the stiffness of joints between the panel and rectangular cavity are used as updating parameters. Robustness of the proposed method under presence of noise is investigated. It is seen that the method is not only able to obtain a close match between FE model and corresponding ‘measured’ vibro-acoustic characteristics but is also able to estimate the correction factors to the updating parameters with reasonable accuracy.

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