scholarly journals Seismic Analysis of a Large LNG Tank Considering Different Site Conditions

2020 ◽  
Vol 10 (22) ◽  
pp. 8121 ◽  
Author(s):  
Yi Zhao ◽  
Hong-Nan Li ◽  
Shuocheng Zhang ◽  
Oya Mercan ◽  
Caiyan Zhang
Keyword(s):  
Seismic Response ◽  
Structural Design ◽  
Well Being ◽  
Von Mises Stress ◽  
Site Conditions ◽  
Storage Tanks ◽  
Site Class ◽  
Lng Tank ◽  
Von Mises ◽  
Site Classes

Seismic resilience of critical infrastructure, such as liquefied natural gas (LNG) storage tanks, is essential to the safety and economic well-being of the general public. This paper studies the effect of different ground motions on large LNG storage tanks under four different site conditions. Key parameters of structural design and dynamic analysis, including von Mises stress of outer and inner tanks, tip displacement, and base shear, are analyzed to directly evaluate the safety performance of the large LNG tanks. Because the size of an LNG tank is too large to perform any experiments on a physical prototype, Smoothed Particle Hydrodynamics-Finite Element Method (SPH-FEM) simulation is used as a feasible and efficient method to predict its seismic response. First, the accuracy of the SPH-FEM method is verified by comparing sloshing frequencies obtained from theoretical formulation to experimental results and SPH-FEM models. Then, the seismic response of a real-life 160,000 m3 LNG prestressed storage tank is evaluated with different liquid depths under four site classes. Simulation results show that the tip displacements of the LNG tank at liquid levels of 25% and 50% under site class IV are nearly identical to that of 75% and 100% under site class II. In addition, the maximum von Mises stress of the inner tanks exceeds 500 MPa in all four site classes and jeopardizes the structural integrity of large LNG tanks. As a result, optimization of structural design and the establishment of an early warning system are imperative to the safety of LNG tanks at high liquid levels.

Floating Roof Influence on Seismic Response of Large Vertical Storage Tank

2013 ◽  
Vol 671-674 ◽  
pp. 1399-1402
Author(s):  
Ying Sun ◽  
Jian Gang Sun ◽  
Li Fu Cui
Keyword(s):  
Seismic Response ◽  
Storage Tank ◽  
Numerical Solutions ◽  
Fluid Pressure ◽  
Seismic Intensity ◽  
Site Conditions ◽  
Storage Tanks ◽  
Analysis Model ◽  
Base Shear ◽  
The Impact

To study the impact of floating roof on seismic response of vertical storage tank structure system subjected to seismic excitation, select 150000m3 storage tanks as research object, and the finite element analysis model of storage tanks with and without floating roof were established respectively. The seismic response of these two types of structure in different site conditions and seismic intensity were calculated and the numerical solutions were compared. The results show that floating roof has little impact on base shear and base moment in different site conditions and seismic intensity. Floating roof can effectively reduce the sloshing wave height. The influence of floating roof on dynamic fluid pressure decreases with the increase of seismic intensity, which is less affected by ground conditions.

scholarly journals Numerical Analysis of the Crack Inspections Using Hybrid Approach for the Application the Circular Cantilever Rods

2021 ◽  
Vol 29 (2) ◽  
Author(s):  
Saddam Hussein Raheemah ◽  
Kareem Idan Fadheel ◽  
Qais Hussein Hassan ◽  
Ashham Mohammed Aned ◽  
Alaa Abdulazeez Turki Al-Taie ◽  
...  
Keyword(s):  
Structural Design ◽  
Hybrid Approach ◽  
Von Mises Stress ◽  
Whole Body ◽  
Total Deformation ◽  
Motion Equations ◽  
Maximum Deformation ◽  
Simulation Process ◽  
Maximum Value ◽  
Von Mises

The present study aims to investigate crack presence in a rigid steel beam so that it can be considered in structural design. A finite element method (FEM) had been used with the Ansys 16.1 software to simulate the whole steel body with three different forces and moments with a magnitude force subjected at the free end of the beam. The steel rod had been considered as simple cantilever to be modelled by the software. Von Mises stress had been considered in the simulation process where the maximum value of stress due to applied load and moment was 1.9 MPa. Total deformation of the whole body had also been considered to instigate the maximum deformation (4.3mm) due to applied loads and moments. Furthermore, MATLAB and through fuzzy logic had been used to assist in the investigation of cracks. Both approaches had been governed by the Euler-Bernoulli theory for free vibration of motion equations. The other aim of this study is to evaluate results received from the Ansys with MATLAB for the same boundary conditions as the case.

scholarly journals A study on sensitivity of seismic site amplification factors to site conditions for bridges

2018 ◽  
Vol 51 (4) ◽  
pp. 197-211
Author(s):  
Muhammad Tariq A. Chaudhary
Keyword(s):  
Seismic Design ◽  
Site Amplification ◽  
Site Conditions ◽  
Design Codes ◽  
Design Code ◽  
Bridge Design ◽  
Site Class ◽  
Vibration Period ◽  
Amplification Factors ◽  
Site Classes

Seismic site amplification factors and seismic design spectra for bridges are influenced by site conditions that include geotechnical properties of soil strata as well as the geological setting. All modern seismic design codes recognize this fact and assign design spectral shapes based on site conditions or specify a 2-parameter model with site amplification factors as a function of site class, seismic intensity and vibration period (short and long). Design codes made a number of assumptions related to the site conditions while specifying the values of short (Fa) and long period (Fv) site amplification factors. Making these assumptions was necessary due to vast variation in site properties and limited availability of actual strong motion records on all site conditions and seismic setting in a region. This paper conducted a sensitivity analysis for site amplification factors for site classes C and D in the AASHTO bridge design code by performing a 1-D site response analysis in which values of site parameters like strata depth, travel-time averaged shear wave velocity in the top 30 m strata (Vs30), plasticity index (PI), impedance contrast ratio (ICR) and intensity of seismic ground motion were varied. The results were analyzed to identify the site parameters that impacted Fa and Fv values for site classes C and D. The computed Fa and Fv values were compared with the corresponding values in the AASHTO bridge design code and it was found that the code-based Fa and Fv values were generally underestimated and overestimated respectively.

Structural Design and Stress Analysis of a High-Speed Turbogenerator Assembly Supported by Hydrodynamic Bearings

2020 ◽  
Vol 10 (1) ◽  
pp. 54-67
Author(s):  
Rodrigo Teixeira Bento ◽  
André Ferrus Filho ◽  
Marco Antonio Fumagalli
Keyword(s):  
Structural Design ◽  
High Speed ◽  
Fem Analysis ◽  
Electrical Energy ◽  
Von Mises Stress ◽  
Bronze Alloy ◽  
Hydrodynamic Bearings ◽  
Hydrodynamic Bearing ◽  
Critical Components ◽  
Von Mises

Turbine and bushing bearing are the most critical components of high-speed machines. This article describes the design of a high-speed turbine supported by hydrodynamic bearings. The mathematical dimensioning and the FEM analysis are presented to validate the mechanical strength of the turbine and the bushing bearing models. Fatigue life and factor of safety were also determined. The simulations showed that the maximum Von Mises stress values obtained are associated to the centrifugal force generated by the system rotational movement. The results variation was mainly due to the properties of the materials proposed. For the turbine, 7075-T6 aluminum alloy and SAE 4340 steel obtained satisfactory behavior under a constant operating speed of 30,000 RPM. For the hydrodynamic bearing, the TM23 bronze alloy exhibited excellent results, without fracture, and low mechanical deformation. The models exhibited a great potential employment in several applications, such as biogas systems to generate electrical energy, and educational test bench for thermodynamic and tribological simulations.

scholarly journals Structural Design Method for Constructions: Simulation, Manufacturing and Experiment

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6064
Author(s):  
Pavel Bolshakov ◽  
Nikita Kharin ◽  
Ramil Kashapov ◽  
Oskar Sachenkov
Keyword(s):  
Additive Manufacturing ◽  
Structural Design ◽  
Design Method ◽  
Manufacturing Technology ◽  
Von Mises Stress ◽  
Design Concepts ◽  
Additive Manufacturing Technology ◽  
Basic Cell ◽  
Complex Structural ◽  
Von Mises

The development of additive manufacturing technology leads to new concepts for design implants and prostheses. The necessity of such approaches is fueled by patient-oriented medicine. Such a concept involves a new way of understanding material and includes complex structural geometry, lattice constructions, and metamaterials. This leads to new design concepts. In the article, the structural design method is presented. The general approach is based on the separation of the micro- and macro-mechanical parameters. For this purpose, the investigated region as a complex of the basic cells was considered. Each basic cell can be described by a parameters vector. An initializing vector was introduced to control the changes in the parameters vector. Changing the parameters vector according to the stress-strain state and the initializing vector leads to changes in the basic cells and consequently to changes in the microarchitecture. A medium with a spheroidal pore was considered as a basic cell. Porosity and ellipticity were used for the parameters vector. The initializing vector was initialized and depended on maximum von Mises stress. A sample was designed according to the proposed method. Then, solid and structurally designed samples were produced by additive manufacturing technology. The samples were scanned by computer tomography and then tested by structural loads. The results and analyses were presented.

Influence of the distribution of the shear walls on the seismic response of the buildings

2020 ◽  
Vol 15 (1) ◽  
pp. 37-44
Author(s):  
El Mehdi Echebba ◽  
Hasnae Boubel ◽  
Oumnia Elmrabet ◽  
Mohamed Rougui
Keyword(s):  
Structural Analysis ◽  
Seismic Response ◽  
Natural Frequency ◽  
Structural Design ◽  
Structural Response ◽  
Shear Walls ◽  
Structural Elements ◽  
Analysis Software ◽  
Ansys Apdl ◽  
The Impact

Abstract In this paper, an evaluation was tried for the impact of structural design on structural response. Several situations are foreseen as the possibilities of changing the distribution of the structural elements (sails, columns, etc.), the width of the structure and the number of floors indicates the adapted type of bracing for a given structure by referring only to its Geometric dimensions. This was done by studying the effect of the technical design of the building on the natural frequency of the structure with the study of the influence of the distribution of the structural elements on the seismic response of the building, taking into account of the requirements of the Moroccan earthquake regulations 2000/2011 and using the ANSYS APDL and Robot Structural Analysis software.

Effects of occlusal scheme on All-on-Four abutments, screws and prostheses: A three-dimensional finite element study

2020 ◽  
Author(s):  
Nurullah Türker ◽  
Hümeyra Tercanlı Alkış ◽  
Steven J Sadowsky ◽  
Ulviye Şebnem Büyükkaplan
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Good Prognosis ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Group Function ◽  
Occlusal Contact ◽  
Maximum Deformation ◽  
Contact Points ◽  
Von Mises

An ideal occlusal scheme plays an important role in a good prognosis of All-on-Four applications, as it does for other implant therapies, due to the potential impact of occlusal loads on implant prosthetic components. The aim of the present three-dimensional (3D) finite element analysis (FEA) study was to investigate the stresses on abutments, screws and prostheses that are generated by occlusal loads via different occlusal schemes in the All-on-Four concept. Three-dimensional models of the maxilla, mandible, implants, implant substructures and prostheses were designed according to the All-on-Four concept. Forces were applied from the occlusal contact points formed in maximum intercuspation and eccentric movements in canine guidance occlusion (CGO), group function occlusion (GFO) and lingualized occlusion (LO). The von Mises stress values for abutment and screws and deformation values for prostheses were obtained and results were evaluated comparatively. It was observed that the stresses on screws and abutments were more evenly distributed in GFO. Maximum deformation values for prosthesis were observed in the CFO model for lateral movement both in the maxilla and mandible. Within the limits of the present study, GFO may be suggested to reduce stresses on screws, abutments and prostheses in the All-on-Four concept.

The Influence of Loading Position in A Priori High Stress Detection using Mode Superposition

2020 ◽  
Vol 1 (1) ◽  
pp. 93-102
Author(s):  
Carsten Strzalka ◽  
◽  
Manfred Zehn ◽  
Keyword(s):  
Finite Element ◽  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
A Priori ◽  
High Stress ◽  
Von Mises Stress ◽  
Detailed Knowledge ◽  
Variable Loading ◽  
Numerical Effort ◽  
Von Mises

For the analysis of structural components, the finite element method (FEM) has become the most widely applied tool for numerical stress- and subsequent durability analyses. In industrial application advanced FE-models result in high numbers of degrees of freedom, making dynamic analyses time-consuming and expensive. As detailed finite element models are necessary for accurate stress results, the resulting data and connected numerical effort from dynamic stress analysis can be high. For the reduction of that effort, sophisticated methods have been developed to limit numerical calculations and processing of data to only small fractions of the global model. Therefore, detailed knowledge of the position of a component’s highly stressed areas is of great advantage for any present or subsequent analysis steps. In this paper an efficient method for the a priori detection of highly stressed areas of force-excited components is presented, based on modal stress superposition. As the component’s dynamic response and corresponding stress is always a function of its excitation, special attention is paid to the influence of the loading position. Based on the frequency domain solution of the modally decoupled equations of motion, a coefficient for a priori weighted superposition of modal von Mises stress fields is developed and validated on a simply supported cantilever beam structure with variable loading positions. The proposed approach is then applied to a simplified industrial model of a twist beam rear axle.

scholarly journals Numerical Investigation of the Deformable Porous Media Treated by the Intermittent Microwave

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 757
Author(s):  
Tianyi Su ◽  
Wenqing Zhang ◽  
Zhijun Zhang ◽  
Xiaowei Wang ◽  
Shiwei Zhang
Keyword(s):  
Porous Media ◽  
Heat Transport ◽  
Liquid Water ◽  
Von Mises Stress ◽  
Temperature Deformation ◽  
Local Maxima ◽  
Whole Process ◽  
Surface Areas ◽  
Pulse Ratio ◽  
Von Mises

A 2D axi-symmetric theoretical model of dielectric porous media in intermittent microwave (IMW) thermal process was developed, and the electromagnetic energy, multiphase transport, phase change, large deformation, and glass transition were taken into consideration. From the simulation results, the mass was mainly carried by the liquid water, and the heat was mainly carried by liquid water and solid. The diffusion was the dominant mechanism of the mass transport during the whole process, whereas for the heat transport, the convection dominated the heat transport near the surface areas during the heating stage. The von Mises stress reached local maxima at different locations at different stages, and all were lower than the fracture stress. A material treated by a longer intermittent cycle length with the same pulse ratio (PR) tended to trigger the phenomena of overheat and fracture due to the more intense fluctuation of moisture content, temperature, deformation, and von Mises stress. The model can be extended to simulate the intermittent radio frequency (IRF) process on the basis of which one can select a suitable energy source for a specific process.

scholarly journals Finite Element Analysis of Composite Repair for Damaged Steel Pipeline

Coatings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 301
Author(s):  
Jiaqi Chen ◽  
Hao Wang ◽  
Milad Salemi ◽  
Perumalsamy N. Balaguru
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Hoop Stress ◽  
Pipe Wall ◽  
Von Mises Stress ◽  
Repair System ◽  
Composite Repair ◽  
Steel Pipeline ◽  
Von Mises ◽  
Infill Material

Carbon fiber reinforced polymer (CFRP) matrix composite overwrap repair systems have been introduced and accepted as an alternative repair system for steel pipeline. This paper aimed to evaluate the mechanical behavior of damaged steel pipeline with CFRP repair using finite element (FE) analysis. Two different repair strategies, namely wrap repair and patch repair, were considered. The mechanical responses of pipeline with the composite repair system under the maximum allowable operating pressure (MAOP) was analyzed using the validated FE models. The design parameters of the CFRP repair system were analyzed, including patch/wrap size and thickness, defect size, interface bonding, and the material properties of the infill material. The results show that both the stress in the pipe wall and CFRP could be reduced by using a thicker CFRP. With the increase in patch size in the hoop direction, the maximum von Mises stress in the pipe wall generally decreased as the maximum hoop stress in the CFRP increased. The reinforcement of the CFRP repair system could be enhanced by using infill material with a higher elastic modulus. The CFRP patch tended to cause higher interface shear stress than CFRP wrap, but the shear stress could be reduced by using a thicker CFRP. Compared with the fully bonded condition, the frictional interface causes a decrease in hoop stress in the CFRP but an increase in von Mises stress in the steel. The study results indicate the feasibility of composite repair for damaged steel pipeline.

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