Float-Over Installation Analysis of Semisubmersible Production Platform Topside

2018 ◽  
Author(s):  
Chen Gang ◽  
Zhang Huan ◽  
Wang Yuhan ◽  
Wang Chao ◽  
Zhang Wei ◽  
...  
Keyword(s):  
Offshore Platforms ◽  
Loading Conditions ◽  
Motion Response ◽  
Movement Condition ◽  
Production Platform ◽  
Lifting Capacity ◽  
Calculation Results ◽  
Floating Crane ◽  
Coupling Calculation ◽  
Mating Unit

Compared with split lifting by floating crane, the float-over is less time-consuming and has larger lifting capacity, especially suitable for large and medium sized offshore platforms. Float-over installation process of a deepwater semisubmersible platform topside is analyzed in this paper. And the multi-floating coupling calculation is carried out in the typical loading conditions of mating process between topside and column top structure. The motion response of leg mating unit in position of barge is received. The calculation results show that the float movement condition meets float-over installation requirements of topside. The analysis can provide a reference for the project of the float-over installation in the future.

Study on the Motion Response of Buoy in Sea Condition

2013 ◽  
Vol 712-715 ◽  
pp. 1335-1338
Author(s):  
Yan Gang Wang ◽  
Xing Hua Tong ◽  
Lin Sen Zhu ◽  
Yong Liu
Keyword(s):  
Basal Area ◽  
The Other ◽  
Mooring Line ◽  
Wave Power ◽  
Loading Conditions ◽  
Power Devices ◽  
Motion Response ◽  
Axis Direction ◽  
Floating System ◽  
The Mean

In the research of buoy wave power devices, earlier studies have indicated that the vertical cylindrical can absorb the most power from wave by comparing the loading conditions of several buoys (e.g.cuboid, vertical cylindrical, horizontal cylindrical, sphere, and so on) using the Froude-Krylov theory. However, it is not argued the motion response of buoys with the same basal area and the different basal shapes. In this paper, buoys with the same basal area and the different basal shapes are investigated by the mean of simulation. There are two modes for the floating system, one is with mooring line and the other is without. In both cases, the motions in horizontal (x axis) and vertical (z axis) direction will be studied.

scholarly journals Semi-submersible Offshore Coupled Motion in Irregular Waves

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Baoji Zhang ◽  
Ying Wang
Keyword(s):  
Return Period ◽  
Simple Algorithm ◽  
Wave Force ◽  
Hydrodynamic Performance ◽  
Irregular Waves ◽  
Offshore Platforms ◽  
Wave Direction ◽  
Motion Response ◽  
Irregular Wave ◽  
Control Equation

In order to predict the hydrodynamic performance of semi-submersible offshore platform accurately, based on CFD theory, continuous equation and N-S equation as the control equation, RNG type k-ε model as turbulence model, using the finite difference method to discretize the control equation，using the Semi-Implicit Method for Pressure Linked Equation (SIMPLE) algorithm to solve the control equation，using the VOF method to capture the free surface. The numerical wave tank of irregular wave is established, and the wave force and motion response of the semi-submersible platform under irregular wave are studied. Based on the Jonswap spectrum density function, for a certain area of two irregular waves (South China sea, a-ten-year return period, a-hundred-year return period) sea condition, five wave direction Angle (0 °, 30 °, 45 °, 60 °, 90 °), a total of 10 kinds of conditions of the motion response of semi-submersible platform are simulated, through analysis and comparison of simulation results, the influence law of wave angle, wave period and wave height on platform motion is obtained. Compared with the experimental values, the results of heave and pitch are close to the experimental data under the sea condition of 2, 0 degree wave angles. The research results in this paper can provide reference for the design and motion response prediction of practical semi-submersible offshore platforms.

An Anisotropic Constitutive Model for a Directionally Solidified Superalloy

2007 ◽  
Vol 340-341 ◽  
pp. 901-906 ◽  
Author(s):  
Masatsugu Yaguchi ◽  
Masato Yamamoto ◽  
Takashi Ogata ◽  
Nobutada Ohno
Keyword(s):  
Constitutive Model ◽  
Inelastic Strain ◽  
Transversely Isotropic ◽  
Loading Conditions ◽  
Directionally Solidified ◽  
Creep Tests ◽  
Static Recovery ◽  
Calculation Results ◽  
Multiaxial Creep ◽  
Creep Loading

The monotonic tensile and creep deformations of a directionally solidified (DS) superalloy are investigated for several loading directions. The material exhibits remarkable anisotropy under elastic and creep loading conditions, whereas it shows isotropy under loading conditions of high strain rates. Tension-torsion creep tests are also conducted to investigate the deformation under multiaxial stress conditions. Referring to the observed behavior, a unified constitutive model, which has two features, is developed for the DS superalloy. One is a static recovery term of back stresses that is prescribed as a transversely isotropic property, which is supposed to have an effect on the deformation behavior under creep loading conditions. The other is the division of inelastic strain into two components, which represent octahedral and cubic slip system deformations, so as to describe multiaxial creep deformation. Calculation results obtained using the constitutive model are compared with the uniaxial and multiaxial experimental results to evaluate the validity of the model.

scholarly journals Numerical Simulation and Experimental Study on the Gas-Solid Coupling of the Aerostatic Thrust Bearing with Elastic Equalizing Pressure Groove

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Zhao Xiao-long ◽  
Zhang Jun-an ◽  
Dong Hao ◽  
Fang Zhou ◽  
Li Jun-ning
Keyword(s):  
Numerical Simulation ◽  
Thrust Bearing ◽  
Aerostatic Bearing ◽  
Deformation Control ◽  
Good Consistency ◽  
Calculation Results ◽  
Bearing Stiffness ◽  
Low Stiffness ◽  
Coupling Calculation ◽  
Control Equation

Aiming at the problem of low stiffness of aerostatic bearing, according to the principle of gas-solid coupling, this paper designs a kind of aerostatic thrust bearing with elastic equalizing pressure groove (EEPG) and investigates the effect of elastic equalizing pressure groove (EEPG) on the stiffness of aerostatic bearing. According to the physical model of the bearing, one deduces the deformation control equation of the elastic equalizing pressure groove and the control equation of gas lubrication, using finite difference method to derive the control equations and coupling calculation. The bearing capacity and stiffness of aerostatic bearing with EEPG in different gas film clearance are obtained. The calculation results show that the stiffness increased by 59%. The results of numerical calculation and experimental results have good consistency, proving the gas-solid coupling method can improve the bearing stiffness.

scholarly journals Selection and calculation of traction elements of the elevator lifting mechanism

2021 ◽  
Vol 7 (3) ◽  
pp. 205-216
Author(s):  
P.V. Vitchuk ◽  
◽  
N.D. Reykhert ◽  
N.A. Vitchuk ◽  
◽  
...  
Keyword(s):  
Correct Choice ◽  
Optimal Parameters ◽  
Kinematic Scheme ◽  
Second Stage ◽  
The Third ◽  
Third Stage ◽  
Lifting Capacity ◽  
Calculation Results ◽  
The Masses ◽  
Selection Of

The correct choice of elements of the elevator lifting mechanism and their parameters ensures its reliability, durability, energy and economic efficiency. The paper contains recommendations for the selection of the traction elements of the elevator lifting mechanism and the sequence of determining their parameters based on a multivariate calculation. The purpose of the proposed sequence is to obtain the most rational parameters of the traction elements of the elevator lifting mechanism. The initial data for the calculation are the lifting capacity of the elevator, the nominal speed of movement, the height of the lift of the car. It is also necessary to consider the purpose of the elevator. At the first stage of the calculation, the masses of the cab and the counterweight are determined. In this case, the existing data on analogue lifts should be used. In the absence of such data, the approximate dependences proposed by the authors of the article can be used. At the second stage, the kinematic scheme of the elevator is selected. At the third stage, the type of traction element is selected. On the basis of domestic and foreign experience in elevator engineering and well-known literature, recommendations are formulated for choosing the type of traction element. The final stage is a multivariate calculation of traction elements. It is proposed to evaluate the calculation results taking into account the minimum value of the safety factor in accordance with the EN 81-1: 1998 standard. The calculation of the traction elements considered in the work is only a small part of the process of determining the optimal parameters of the elements of the elevator lifting mechanism. At the same time, already at this stage, variability is introduced, which makes the calculation quite laborious to perform it manually. Obviously, a multivariate calculation method that allows you to analyze many different combinations of parameters of the elements of the elevator lifting mechanism and choose the optimal ones is impossible without the use of a computer.

A Stress Check Procedure for Pipe Lowering-In Process During Pipeline Construction

2014 ◽  
Author(s):  
Da-Ming Duan ◽  
Thomas Jurca ◽  
Charles Zhou
Keyword(s):  
Finite Element ◽  
Stress Level ◽  
Height Profile ◽  
Element Analysis ◽  
Pipeline Construction ◽  
Lifting Capacity ◽  
Calculation Results ◽  
Construction Condition ◽  
Construction Practice

The quality of pipeline construction is determined by the effort of controlling the pipe stress level. Constraints may include various factors, such as pipe size, side boom lifting capacity, the number of side booms, side boom spacing and the lifting height profile. The use of girth weld flaw size limit established by Engineering Critical Assessment (ECA) for a given construction condition, makes the accuracy of pipe stress even more important. This is not only because stress level is one of the controlling parameters of the ECA results, but also because in some cases, such as low girth weld fracture toughness, stress level must be controlled with a very narrow window to keep a meaningful ECA that leads to a reasonable weld repair rate. An optimized pipe lifting height profile can be obtained from stress analysis using finite element method based on available construction equipment capabilities. From a practical perspective, an optimized pipe lowering-in plan may not be executable in the construction field. It is thus desired that a practical approach be provided that captures the key feature of construction practice and at the same time makes the key measures recordable. This paper provides a set of stress check equations derived using beam deformation theory. The calculation results using these equations show that for normal pipe lowering-in practice, pipe stress level can be effectively controlled by checking and controlling the lifting height of just one or two points. The approach proposed is to be used in conjunction with case specific finite element analysis.

Summer Ice Floe Impacts Against Caisson-Type Exploratory and Production Platforms

1984 ◽  
Vol 106 (2) ◽  
pp. 169-175 ◽  
Author(s):  
P. Croteau ◽  
M. Rojansky ◽  
B. C. Gerwick
Keyword(s):  
Rational Design ◽  
Oil And Gas ◽  
Structural Response ◽  
Offshore Platforms ◽  
Relative Importance ◽  
Analysis Techniques ◽  
Response Characteristics ◽  
Production Platform ◽  
Ice Floes ◽  
The Impact

Summer impacts of large ice floes against arctic offshore platforms are likely to be a governing condition for the global foundation stability in medium and deep-water offshore platforms in the Alaskan Beaufort Sea. Some features of the impact phenomenon are illustrated by analyzing two vertically faced caisson-type gravity platforms. The two structures differ in their function, size and environmental exposure: the first is a smaller exploratory drilling caisson while the other is for production of oil and gas. Both structures are assumed to be in 30 m of water. A description of the analysis techniques is given: it is based on a dynamic modeling which considers the effects of inertia, damping, foundation compliance and slippage at the base in addition to a crushing failure mechanism in the ice at the contact area. Comparisons are made between the structural response computed for both the exploratory and production platform and for typical “soft” and “firm” site conditions. A discussion as to the relative importance of various design and modeling parameters is presented. The comparison of response characteristics of the assumed structures provides some insight for the purpose of formulating rational design criteria with regard to ice floe impact.

scholarly journals Experimental Study on Development of Mooring Simulator for Multi Floating Cranes

2021 ◽  
Vol 9 (3) ◽  
pp. 344
Author(s):  
Junhyeok Bae ◽  
Juhwan Cha ◽  
Min-Guk Seo ◽  
Kangsu Lee ◽  
Jaeyong Lee ◽  
...  
Keyword(s):  
Model Test ◽  
Equations Of Motion ◽  
Mooring Line ◽  
Analysis Program ◽  
The Finite Element Method ◽  
Mooring Lines ◽  
Calculation Results ◽  
Floating Crane ◽  
Pile Model ◽  
Equations Of Motions

In this study, the coupled motion of a mooring system and multifloating cranes were analyzed. For the motion analysis, the combined equations of motions of the mooring line and multifloating cranes were introduced. The multibody equations for floating cranes were derived from the equations of motion. The finite element method (FEM) was used to derive equations to solve the stretchable catenary problem of the mooring line. To verify the function of mooring simulator, calculation results were compared with commercial mooring software. To validate the analysis results, we conducted an experimental test for offshore operation using two floating crane models scaled to 1:40. Two floating crane models and a pile model were established for operation of uprighting flare towers. During the model test, the motion of the floating cranes and tensions of the mooring lines were measured. Through the model test, the accuracy of the mooring analysis program developed in this study was verified. Therefore, if this mooring analysis program is used, it will be possible to perform a mooring analysis simulation at the same time as a maritime work simulation.

Analysis of Strengthening Methods for Retained Exterior Walls during a Structural Retrofit

2010 ◽  
Vol 133-134 ◽  
pp. 929-933
Author(s):  
Yu Ouyang ◽  
Ying Hu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Retaining Walls ◽  
Loading Conditions ◽  
Analysis Software ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Calculation Results ◽  
Story Building

A three-story old building made up of masonry and wood will be retrofitted to be a new 14-story building, retaining two exterior walls and removing all internal members. To prevent the retained walls form deforming severely or collapse during the retrofit is necessary. The finite element analysis software, ANSYS, is used to calculate the responses of the retaining walls under possible loading conditions. The original retrofit proposal for the old building is refined based on the calculation results.

Reliability-Based Screening of Offshore Platforms

1998 ◽  
Vol 120 (3) ◽  
pp. 139-148 ◽  
Author(s):  
R. G. Bea ◽  
M. M. Mortazavi
Keyword(s):  
Reliability Analysis ◽  
Failure Modes ◽  
Screening Procedure ◽  
Weak Links ◽  
Offshore Platforms ◽  
Production Platform ◽  
First Order Second Moment ◽  
Detailed Assessment ◽  
Reliability Methods ◽  
Potential Failure

This paper describes development of a reliability-based screening procedure for platform assessments and requalifications. The objective of this procedure is to identify the critical structures and structure components that need to undergo a detailed assessment so that limited resources can be efficiently used. The reliability-based screening procedure helps identify potential failure modes and weak links in the structure, and provides information on the effects of load reduction and strengthening measures on the reliability of the platform. The reliability analysis screening procedure is based on a first-order second-moment (FOSM) formulation. A study is summarized of the implications of the simplified FOSM method. In the case of an eight-leg drilling and production platform located in the Gulf of Mexico, the results from FOSM reliability analysis are compared with those from first and second-order reliability methods (FORM and SORM). There is excellent agreement between the FOSM and FORM/SORM results.

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