Assessment of Dynamic High Momentum Slug Loads on Piping Following STHE Tube Rupture

2021 ◽  
Author(s):  
Robert Weyer
Keyword(s):  
Slug Flow ◽  
Time History ◽  
Dimensional Change ◽  
Dynamic Loads ◽  
Finite Element Models ◽  
High Momentum ◽  
Force Vector ◽  
Shell Elements ◽  
3 Dimensional ◽  
Process Piping

Abstract Transient fluid loads in process piping have gained renewed focus recently with the design and construction of many LNG plants. The case of the shockwave (waterhammer) in piping following the rupture of a tube in a STHE has been well studied. Less attention has been paid to the high momentum slug flow which can occur when liquid slugs are accelerated in the piping by the gas. This paper will examine some of the practical considerations for assessing the dynamic loads resulting from this high momentum slug flow. A method to obtain the force vector for any 3-dimensional change in direction will be presented. The use of DLFs for loads where a detailed time history profile is available will be discussed. The possibility of taking credit for simultaneously acting forces will be investigated. The applicability of the B31.3 allowable stress for occasional loads will be examined and compared against advanced finite element models using shell elements.

Fatigue Life Prediction of Drill-String Subjected to Random Loadings

2014 ◽  
Author(s):  
Jiahao Zheng ◽  
Hongyuan Qiu ◽  
Jianming Yang ◽  
Stephen Butt
Keyword(s):  
Fatigue Life ◽  
Time History ◽  
Beam Theory ◽  
Drill String ◽  
Finite Element Models ◽  
Bernoulli Beam ◽  
Stress Cycles ◽  
Rainflow Counting ◽  
Euler Bernoulli Beam ◽  
Random Nature

Based on linear damage accumulation law, this paper investigates the fatigue problem of drill-strings in time domain. Rainflow algorithms are developed to count the stress cycles. The stress within the drill-string is calculated with finite element models which is developed using Euler-Bernoulli beam theory. Both deterministic and random excitations to the drill-string system are taken into account. With this model, the stress time history in random nature at any location of the drill-string can be obtained by solving the random dynamic model of the drill-string. Then the random time history is analyzed using rainflow counting method. The fatigue life of the drill-string under both deterministic and random excitations can therefore be predicted.

Experimental Study and Numerical Analysis of Sihui Metro Depot and the Superstructure

2012 ◽  
Vol 226-228 ◽  
pp. 176-180
Author(s):  
Jing Zhang ◽  
Bin Zhang ◽  
Ying Hua Liu ◽  
Long Qi Wang ◽  
Yu Bin Wu
Keyword(s):  
Time History ◽  
Field Tests ◽  
Element Model ◽  
Test Analysis ◽  
3 Dimensional ◽  
Dimensional Finite Element ◽  
Calculation Results ◽  
History Of ◽  
The Given ◽  
The Waves

Field tests were carried out on Sihui metro depot of Beijing metro line 1 and its superstructure. The acceleration time history of sleepers and floors of the building was obtained, and the waves-propagation laws of building were studied through the tests. Test analysis shows that the structure vibrations show zigzag tendencies ascends with the height of the building. Based on current situation of Sihui metro depot, a metro-soil-building 3-dimensional finite element model is established on ANSYS. By using actual acceleration of sleepers as inputs, the dynamic responds rule of the superstructure is obtained. Compared calculation results with the experimental results, the given numerical model can predict the vibrations of the building induced by moving trains quite well. This method can provide guidance and technical support for future development of superstructure.

Analysis of the Seismic Performance of RC Frame Structures with Different Types of Bracings

2012 ◽  
Vol 166-169 ◽  
pp. 2209-2215
Author(s):  
Zhi Xin Wang ◽  
Hai Tao Fan ◽  
Huang Juan Zhao
Keyword(s):  
Seismic Performance ◽  
Time History ◽  
Steel Tube ◽  
Frame Structure ◽  
Frame Structures ◽  
Finite Element Models ◽  
Base Shear ◽  
Concrete Filled Steel Tube ◽  
Different Types ◽  
Rc Frame Structures

Finite element models of frames with steel-bracings and with concrete filled steel tube struts are built in ETABS. Seismic performance of these models is analyzed with base-shear method, superposition of modal responses method and time history method respectively. The results show that the steel-bracings or concrete filled steel tube struts are efficient to increase the story-stiffness, and the top displacement of the frame structure decreases significantly.

Dynamic Burst Pressure Simulation of Cylinder-Cylinder Intersections

2008 ◽  
Author(s):  
Cunjiang Cheng ◽  
G. E. Otto Widera
Keyword(s):  
Finite Element ◽  
Wall Thickness ◽  
Time History ◽  
Correlation Equation ◽  
Burst Pressure ◽  
Dynamic Simulations ◽  
Static Test ◽  
Shell Elements ◽  
Dynamic Correlation ◽  
Parameter Ranges

In this study, the determination of the burst pressure of a series of cylinder-cylinder intersections representing vessels of diameter D and wall thickness T, and nozzles of diameter d and wall thickness t subjected to short-term dynamic loading is investigated. Dynamic simulations via the use of the finite element method are carried out to determine the effects of dimensionless parameters d/D, D/T and t/T as well as pressure vs. time history. The LS-DYNA software is employed to model and analyze various intersections for the geometric parameter ranges 0.1 ≤ d/D < 1.0, 0.1 ≤ t/T ≤ 3 and 50 ≤ D/T ≤ 250. The use of both solid and shell elements is investigated and applied in this study. A correlation equation to predict the dynamic burst pressure of cylinder-cylinder intersections is proposed based on the parametric finite element analyses. Static test data is used to verify the dynamic correlation equation by applying a relatively long pressure pulse duration.

Analysis of Pressure Vessel Sloshing

2006 ◽  
Author(s):  
S. M. McGuffie ◽  
M. A. Porter
Keyword(s):  
Pressure Vessel ◽  
Time History ◽  
Transient Time ◽  
Closed Form Solutions ◽  
3 Dimensional ◽  
Fluid Sloshing ◽  
History Analysis ◽  
Division 1 ◽  
Section Viii ◽  
Computational Fluid Dynamics Cfd

ASME BPVC Section VIII Division 1 Paragraph UG-22 (f) requires consideration of the loadings from seismic conditions. For a vessel containing a fluid, the loading due to sloshing must be considered. ASCE Standard 7-02 (Section 9.14.7.3) states that a damping value of 0.5% can be used to account for the fluid sloshing. This can lead to an overly conservative design by over-estimating the loads on the tank structure. A time-history analysis was performed on a horizontally mounted pressure vessel experiencing 3-axis time history loads in order to determine if this method is more accurate in determining the loads. The analysis employed a 3-dimensional computational fluid dynamics (CFD) model, using transient time-history techniques. The reactions at the mounting locations were compared to the reactions computed using closed form solutions, demonstrating good correlation. The results show that CFD is an excellent tool for investigating seismic sloshing loads in vessels.

Influence of Earthquake Attack Angle on Seismic Demands for Structures under Bi-Directional Ground Motions

2011 ◽  
Vol 255-260 ◽  
pp. 2330-2334 ◽  
Author(s):  
Yu Zhang ◽  
Quan Wang Li ◽  
Jian Sheng Fan
Keyword(s):  
Seismic Design ◽  
Ground Motions ◽  
Time History ◽  
Earthquake Excitation ◽  
Seismic Demands ◽  
3 Dimensional ◽  
Nonlinear Time History Analyses ◽  
Modification Factor ◽  
Structural Responses ◽  
Nonlinear Time History

The earthquake may attack the structural building from any angle, but in current seismic design codes, this type of uncertainty is seldom accounted. The uncertainty associated with the direction of earthquake excitation was considered in this paper, and its effect on structural responses was investigated. For this purpose, a simple 3-dimensional model with symmetric plan was established, which had fundamental periods ranged from 0.1s to 5.0s, and was subjected to a set of 30 ground motion pairs for which both linear and nonlinear time history analyses were performed. Analyzing results showed that, on average, the elastic roof acceleration is 32% underestimated, and the inelastic roof displacement is 18% underestimated if the variation of earthquake excitation direction is not consider. Recognizing this, a modification factor for the seismic demand was proposed thorough a statistical analysis, which guarantees a probability of 95% design safety

scholarly journals Comparison of Modelling Strategies of R.C Walls for Seismic Analysis

2021 ◽  
Vol 1197 (1) ◽  
pp. 012067
Author(s):  
Syed Hamim Jeelani ◽  
Salim Akhtar ◽  
N Lingeshwaran ◽  
Durga Chaitanya Kumar Jagarapu ◽  
M A Mohammed Aslam ◽  
...  
Keyword(s):  
Seismic Analysis ◽  
Response Spectrum ◽  
Time History ◽  
Shell Element ◽  
Point Of View ◽  
Element Discretization ◽  
Shell Elements ◽  
Design Engineers ◽  
Equivalent Strut ◽  
Modelling Strategies

Abstract Reinforced concrete walls are being widely adopted as lateral load resisting systems for high rise structures. The current practice among design engineers for modelling of such walls is by idealizing the same as ‘wide’ columns, which is uncertain from safety as well as economy point of view. The most efficient modelling strategy of RC walls involves use of shell elements. Such an approach can be computationally much intensive, especially from a seismic analysis perspective. The present study utilizes an equivalent strut approach for modelling RC walls. The modelling strategy is demonstrated on a G + 15 storey residential apartment located in Calicut city. The proposed methodology will be compared with the traditional ‘wide’ column method as well as the one with shell element discretization. Comparison of modal properties such as frequencies and vibration modes from the various models are initially made to assess the model accuracy. Various seismic analyses viz. Equivalent static approach, Response spectrum approach and the assessment the storey shear, inter storey drifts as well as computation times using various models were performed using time history analysis. From preliminary results, it is understood that the modelling strategy could serve as an efficient alternative to more robust and computationally demanding scheme involving use of shell elements.

scholarly journals Dynamic Response Of Tower Structures

2015 ◽  
Vol 2 ◽  
pp. 85
Author(s):  
Liga Gaile ◽  
Ivars Radinsh
Keyword(s):  
Finite Element ◽  
Structural Changes ◽  
Natural Frequencies ◽  
Resonance Effect ◽  
Dynamic Loads ◽  
Mode Shapes ◽  
Finite Element Models ◽  
Dynamic Parameters ◽  
Vibration Level ◽  
Tower Structure

The present study focuses on the tower type structures response to the dynamic loads. The study analyzes the possible mode shapes regarding to tower structure. The estimation of mode shapes and their dependence from structural changes was made for an existing tower structure. To get an acceptable tower’s vibration level and avoid possibility of resonance effect from usual serviceability loads it was evaluated options to change natural frequencies of the structure. It is performed existing 36m high sightseeing tower dynamic analysis and proposed potential solutions to increase critical natural frequencies of the structure. In this study to obtain dynamic parameters of the sightseeing tower structure have been used finite element models and calculation techniques.

Effect of Geometric and Material Discontinuities on the Reeling of Pipelines

2014 ◽  
Author(s):  
Yafei Liu ◽  
Stelios Kyriakides
Keyword(s):  
Large Scale ◽  
Kinematic Hardening ◽  
Local Buckling ◽  
Nonlinear Finite Element ◽  
Plastic Behavior ◽  
Finite Element Models ◽  
Shell Elements ◽  
Applied Tension ◽  
Material Discontinuities ◽  
Girth Welds

Reeling remains one of the most efficient methods for installing pipelines offshore. The process results in plastic bending, straightening, and reverse bending to strain levels that can be as large as 2–3%. Thus, despite many years of practice, occasional failures during the reeling and unreeling process continue to take place resulting in costly disruptions and repairs. A common cause of such failures is local buckling that can precipitate fracture. This paper presents the results of a study of how discontinuities in geometry and mechanical properties can lead to buckling and failure. Large-scale nonlinear finite element models are used to simulate the reeling/unreeling of pipelines. The pipeline is modeled using shell elements and contact with the hub of the reel is treated appropriately. The elasto-plastic behavior of the steel is modeled using nonlinear kinematic hardening. Typically, a section of pipeline is taken through a winding and unwinding cycle on a reel of a given radius at a constant value of tension. Discontinuities in wall thickness and yield stress such as those that can occur at girth welds are shown to result in sharp local changes in curvature that extend over 3–4 pipe diameters accompanied by severe local straining and ovalization. The combination of these can lead to local buckling. Increase in the applied tension can reduce these at the expense of additional ovalization of the pipeline.

Simplified Dynamic Finite-Element Analysis for Three-Dimensional Pile-Grouped-Raft-High-Rise Buildings

2008 ◽  
Vol 400-402 ◽  
pp. 613-619
Author(s):  
Hui Xiong ◽  
Shou Ping Shang ◽  
Liang Huang
Keyword(s):  
Finite Element ◽  
Structural Engineering ◽  
Computational Cost ◽  
Time History ◽  
Pile Group ◽  
Element Analysis ◽  
Structural Dynamic ◽  
Shell Elements ◽  
High Rise ◽  
Mass Spring

Combined with the respective advantages in S-R(Sway-Rocking) impedance concept and finite-element method, a simplified 3D structural dynamic FEM considering composite pile-group-soil effects is presented. The structural members including piles are modeled by spacial beam or shell elements, and raft-base is divided into thick-shell elements with its spring-dashpot boundary coefficient obtained by impedance backcalculated. The mass-spring elements for soil between piles are set to simulate vertical, horizontal pile-group effects by strata-equivalent approach. The soil beside composite body is separated into near-field and far-field parts. The former is modeled by nonlinear spring-dashpot elements based on Winkler’s hypothesis, while the latter is modeled by a series of linear mass-spring-dashpots. With the effects of boundary track forces and energy radiation, the presented model enables researchers to conduct the time-domain nonlinear analysis in a relatively simple manner which avoids sophisticated boundary method and solid-element mesh bringing with tremendous computational cost. The seismic effect on dynamic interaction of pile-soil-complicated structures would be efficiently annotated from two structural engineering and geotechnical engineering aspects and the numerical calculation effort would be drastically decreased too. The complete procedure is mainly performed using the parametric design language assembled in the Finite Element Code Ansys. With the dynamic analysis of foundation and superstructure for a pile-supported 15-storey building, the influence of the participant effect on structural dynamic response will be depicted by various dynamic parameters of pile-soil-raft foundation in detail. Not only do the results have an agreement with some conclusions drawn by the general interaction theory, but also certain of phenomena which would be disagree with that by general analysis is involved. Even with the finite-element meshes for 68 piles, the time-history analysis procedure for PGSS (Pile-Group-Soil-Superstructure) system and the qualitative evaluation with various SSI parameters can be also fulfilled efficiently and rapidly by presented means. These results may be of help to the designers to quickly assess the significance of interaction effect for the high-rise buildings resting on any type or layout of pile-group foundation.

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