scholarly journals Coupled dynamic response of a three-column mini TLP

2010 ◽  
Vol 6 (2) ◽  
pp. 52-61 ◽  
Author(s):  
Anitha Joseph ◽  
Lalu Mangal ◽  
Precy Sara George
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Wave Force ◽  
Dynamic Responses ◽  
Design Stage ◽  
Force Model ◽  
Diffraction Radiation ◽  
Offshore Platforms ◽  
Scaled Model ◽  
Geometric Configurations

For the development of deepwater marginal fields, many new platform concepts and designs are on the anvil. The mini TLP is a proven concept in this regard wherein an optimised conventional TLP system economically and efficiently serves in developing small marginal deepwater reserves. Various new geometric configurations and designs of mini TLPs are reported in the literature. This paper presents a new geometric configuration which could be a better alternative to an existing configuration. A 3-column mini TLP is designed and its platform-mooring coupled dynamic behaviour is investigated and compared with an existing 4-column mini TLP. The numerical investigation is carried out for the 1:56 scaled model using a finite element computer program suitable for compliant offshore platforms. A combination wave force model with diffraction-radiation loading on large members and Morison loading on slender members is adopted for computing the non-linear dynamic response of the structure. The effects of parameters such as pretension in tethers and wave approach angle have been studied. The results obtained are compared with published results of the 4-column mini TLP. It is found that the dynamic responses of the 3-column mini TLP are close to the 4-column mini TLP with relatively higher surge and tether tension.  Accounting for this in the design stage, the newly designed structure could be a promising candidate which can be used as an alternative to the 4-column mini TLP. Reducing the number of columns from four to three has added advantages in terms of cost and time during fabrication, installation and maintenance of the platform. Keywords: Deepwater structures; Coupled dynamics; Finite element method; Mini TLP; Nonlinear dynamicanalysis. DOI: 10.3329/jname.v6i2.2789

Prediction of the Dynamic Response of a Ship in Head Waves Using OpenFOAM Toolbox

2020 ◽  
Vol 162 (A1) ◽  
Author(s):  
J Yao
Keyword(s):  
Dynamic Response ◽  
Dynamic Responses ◽  
Navier Stokes ◽  
Design Stage ◽  
Offshore Platforms ◽  
Computational Domain ◽  
Marine Structures ◽  
Time Step ◽  
Head Waves ◽  
The Right

Ships and marine structures, such as oil tanker, offshore platforms, etc., usually face extreme seaway environment in real situation. If under the action of strong waves large amplitude motions will occur, with the result that they may not work as usual or even lose stability. Thus, it is of great importance to access their dynamic responses under such bad conditions at the initial design stage, so as to ensure normal usage and safety. Herein, the original RANS (Reynolds-Averaged Navier-Stokes) solver based on OpenFOAM Toolbox has been extended to predict dynamic responses of ships and marine structures in waves. A new “inlet-velocity boundary condition” was implemented to generate waves. A damping term for wave absorption was added to the right-hand side of RANS equations in order to avoid wave reflection from the boundary where waves leave the computational domain. The related numerical methods are described in this paper. The purpose of this paper is to present a validation of the approach used. The prediction of the dynamic response of a ship in head waves was the focus. Five cases with different wave lengths and heights were considered. The predicted results, i.e. time histories of total resistance, heave and pitch, were compared with available experimental data and analysed. In addition, due to current experience it is very necessary that effort is devoted to determining appropriate grid and time step, so as to ensure the quality of waves generated.

PREDICTION OF THE DYNAMIC RESPONSE OF A SHIP IN HEAD WAVES USING OPENFOAM TOOLBOX

2021 ◽  
Vol 162 (A1) ◽  
Author(s):  
J Yao
Keyword(s):  
Dynamic Response ◽  
Dynamic Responses ◽  
Navier Stokes ◽  
Design Stage ◽  
Offshore Platforms ◽  
Computational Domain ◽  
Marine Structures ◽  
Time Step ◽  
Head Waves ◽  
The Right

Ships and marine structures, such as oil tanker, offshore platforms, etc., usually face extreme seaway environment in real situation. If under the action of strong waves large amplitude motions will occur, with the result that they may not work as usual or even lose stability. Thus, it is of great importance to access their dynamic responses under such bad conditions at the initial design stage, so as to ensure normal usage and safety. Herein, the original RANS (Reynolds-Averaged Navier- Stokes) solver based on OpenFOAM Toolbox has been extended to predict dynamic responses of ships and marine structures in waves. A new “inlet-velocity boundary condition” was implemented to generate waves. A damping term for wave absorption was added to the right-hand side of RANS equations in order to avoid wave reflection from the boundary where waves leave the computational domain. The related numerical methods are described in this paper. The purpose of this paper is to present a validation of the approach used. The prediction of the dynamic response of a ship in head waves was the focus. Five cases with different wave lengths and heights were considered. The predicted results, i.e. time histories of total resistance, heave and pitch, were compared with available experimental data and analysed. In addition, due to current experience it is very necessary that effort is devoted to determining appropriate grid and time step, so as to ensure the quality of waves generated.

scholarly journals A 3D Direct Vehicle-Pavement Coupling Dynamic Model and Its Application on Analysis of Asphalt Pavement Dynamic Response

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Peng Cao ◽  
Changjun Zhou ◽  
Decheng Feng ◽  
Youxuan Zhao ◽  
Baoshan Huang
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Dynamic Model ◽  
Static Analysis ◽  
Moving Load ◽  
Dynamic Responses ◽  
Pavement Surface ◽  
Coupling Dynamic ◽  
Pavement Structure ◽  
Coupling Dynamic Model

Currently dynamic response of the pavement structure is widely studied in pavement engineering. A 3D direct vehicle-pavement coupling dynamic model was developed to describe the pavement dynamic responses in this paper. The moving vehicle was simplified as spring-dashpot components, and the pavement structure was simulated using three-dimension finite element model. Based on Newton iteration and central difference integration algorithm, the static and dynamic coupling reactions between the pavement structure and vehicle were considered using finite element platform ABAQUS. The numerical results fit analytic results very well in static analysis and fit experiment results in dynamic analysis well too. The simulated results indicate that the dynamic pavement surface deflection is much higher than the situation in static analysis, due to the overlapping effect. This phenomenon enhances when vehicle speed increases. A discontinuous zone of shear stress was observed on the base surface between the location under moving load and the location the moving load just passed. It was also found that the vertical fluctuation exists on the vehicle even if there is no roughness on the pavement surface. In general, the developed 3-D direct vehicle-pavement coupling dynamic model was validated to be effective on evaluating pavement dynamic responses.

Effect of Seabed Slope on Offshore Pile Lateral Behaviour Under Wave Force

2010 ◽  
Author(s):  
Sathyanarayanan Dhandapani ◽  
Muthukkumaran Kasinathan
Keyword(s):  
Finite Element ◽  
Vertical Direction ◽  
Pile Group ◽  
Element Model ◽  
Wave Force ◽  
Wave Forces ◽  
Extreme Conditions ◽  
Offshore Platforms ◽  
Wave Loads ◽  
Offshore Structure

Fixed offshore platforms supported by pile foundations are required to resist dynamic lateral loading due to wave forces. The response of a jacket offshore tower is affected by the flexibility and nonlinear behavior of the supporting piles. In this study, a typical fixed offshore platform is chosen, and dynamic wave analysis is performed on it. Analysis has been performed for normal environmental conditions and extreme conditions. For the foundation, the deflections and reactions at regular intervals along the vertical direction from the seabed have been found out from the dynamic analysis, and the results have been compared for normal and extreme conditions. The aim of this study is to investigate the effects of the combined lateral and vertical loads on pile group foundation of a fixed offshore structure and the effects of seabed slope on the pile responses. To provide a more accurate and effective design for offshore pile foundation systems under axial structural loads and lateral wave loads, a finite element model which is modelled in FLAC3D is employed herein to determine the soil structure interaction under similar loading conditions. Three dimensional modelling and the analyses are done using FLAC3D — a finite element package.

Dynamic Response of an Elastic-Supported Bridge Beam Subjected to Velocity-Varied Moving Loads

2012 ◽  
Vol 594-597 ◽  
pp. 2802-2807
Author(s):  
Fu Liang Mei ◽  
Gui Ling Li
Keyword(s):  
Dynamic Response ◽  
Beam Theory ◽  
Dynamic Responses ◽  
Force Model ◽  
Superposition Method ◽  
Moving Loads ◽  
Coupled Vibration ◽  
Vehicle Model ◽  
Vibration Model ◽  
Mass Spring

Dynamic response of an elastic-supported bridge under speed-varied moving loads was investigated. A mathematical model of vehicle-bridge coupled oscillation for an elastic-supported bridge was built up by means of 1/4 vehicle model (Mass-Spring-Mass) and Euler-Bernoulli beam theory. And then dynamic equations of vehicle-bridge coupled oscillation in matrix form were established using two former orders general coordinates of an elastic-supported beam and model superposition method. The influences of vehicle-bridge coupled vibration model, elastic-supported stiffness, entrance speeds and acceleration /deceleration of moving loads on the dynamic responses of bridges were studied. Vehicle-bridge coupled vibration model based on 1/4 vehicle model can more accurately describe the dynamic characters of bridges than that based on constant moving force model. Elastic-supported stiffness only has an impact on the fluctuation amplitudes of dynamic responses. The vehicle-induced impact factor is dependent on the entrance speeds, acceleration/deceleration of moving loads and elastic-supported stiffness.

scholarly journals Dynamic Responses of a Twin-Tunnel Subjected to Moving Loads in a Saturated Half-Space

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Hong-lei Sun ◽  
An-hua Chen ◽  
Li Shi ◽  
Xue-yu Geng ◽  
Yu Wang
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Saturated Porous Medium ◽  
Moving Load ◽  
Surrounding Medium ◽  
Element Model ◽  
Dynamic Responses ◽  
3D Finite Element ◽  
Twin Tunnel ◽  
Tunnel Model

With the fast development of rail transit, the environmental vibration problems caused by subways have received increasing attention. A 3D finite element model was built in this study to investigate the ground vibrations induced by the moving load operating in the parallel twin tunnels. Compared to the model consisting of a single tunnel that was commonly adopted in the past studies, a pair of tunnels is considered and the surrounding medium of the tunnels is taken as a saturated porous medium. The governing equations of the 3D finite element method modeling of the saturated poroelastic soil have been derived according to Biot’s theory. Computed results showed that the dynamic response of the twin-tunnel model is greater than that of the single tunnel model. And the spacing between two tunnels, tunnel buried depth, and load moving speed are the essential parameters to determine the dynamic response of the tunnel and soil.

scholarly journals Experiment and Numerical Simulation of the Dynamic Response of Bridges under Vibratory Compaction of Bridge Deck Asphalt Pavement

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
An-Ping Peng ◽  
Han-Cheng Dan ◽  
Dong Yang
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Field Experiments ◽  
Bridge Deck ◽  
Asphalt Pavement ◽  
Dynamic Responses ◽  
Structural Safety ◽  
Cross Sectional ◽  
Bridge Structures ◽  
Vibratory Compaction

Vibratory compaction of bridge deck pavement impacts the structural integrity of bridges to certain degrees. In this study, we analyzed the dynamic response of different types of concrete-beam bridges (continuous beam and simply supported beam) with different cross-sectional designs (T-beam and hollow-slab beam) under vibratory compaction of bridge deck asphalt pavement. The dynamic response patterns of the dynamic deformation and acceleration of bridges under pavement compaction were obtained by performing a series of field experiments and a three-dimensional finite element simulation. Based on the finite element model, the dynamic responses of bridge structures with different spans and cross-sectional designs under different working conditions of vibratory compaction were analyzed. The use of different vibration parameters for different bridge structures was proposed to safeguard their structural safety and reliability.

Nonlinear Dynamic Behavior of Fixed Jacket-Type Offshore Platforms Subjected to Simultaneously Acting Wave and Earthquake Loads

2004 ◽  
Author(s):  
A. K. Etemad ◽  
A. R. M. Gharabaghi ◽  
M. R. Chenaghlou
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Dynamic Response ◽  
Dynamic Behavior ◽  
Persian Gulf ◽  
Nonlinear Dynamic ◽  
Longitudinal Component ◽  
Offshore Platforms ◽  
Nonlinear Dynamic Response ◽  
Earthquake Loads

The nonlinear dynamic response of jacket-type offshore platform (which has been installed in Persian Gulf) under simultaneously wave and earthquake loads is conducted. The interaction between soil and piles is modeled by Konagai-Nogami model. The structure is modeled by finite element method. The analyses include models with the longitudinal component of earthquake and wave in the same direction and in different directions. The results indicate that when the longitudinal component of earthquake and wave are in the same direction, wave may reduce the response of studied platform and when they are in different directions, in some cases there is an increase in the response of platform.

Dynamic Response of Multi-bay Frames Subjected to Successive Moving Forces

2019 ◽  
Vol 19 (04) ◽  
pp. 1950042
Author(s):  
Salih Demirtas ◽  
Hasan Ozturk ◽  
Mustafa Sabuncu
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Moving Load ◽  
Single Point ◽  
Vertical Direction ◽  
Point Load ◽  
Dynamic Responses ◽  
Moving Loads ◽  
Element Analysis ◽  
Constant Interval

This paper investigates the dynamic responses of multi-bay frames with identical bay lengths subjected to a transverse single moving load and successive moving loads with a constant interval at a constant speed. The effects of the bay length and the speed of the moving load on the response of the multi-bay frame subjected to a single point load are investigated numerically by the finite element method. A computer code is developed by using MATLAB to perform the finite element analysis. The Newmark method is employed to solve for the dynamic responses of the multi-bay frame. With this, the dynamic response of the frame subjected to successive moving loads with a constant interval is investigated. Also, the resonance and cancellation speeds are determined by using the 3D relationship of speed parameter-force span length to beam length ratio-dynamic magnification factor and the associated contour lines. The maximum impact factor of a 1-bay frame and multi-bay frames under single moving load are determined at the specific speed parameters. Those values are independent of elastic modulus, area moment of inertia, beam/column lengths of the frame and also the number of bays forming the frame. It is also found that the first resonance response in the vertical direction of the frame is related to the second mode of vibration.

The Influences on Turnout Dynamic Responses due to its Irregularities

2011 ◽  
Vol 105-107 ◽  
pp. 1181-1186 ◽  
Author(s):  
Yang Cao ◽  
Wang Ping ◽  
Wei Hua Zhao ◽  
Cai You Zhao
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Dynamic Response ◽  
Structure Design ◽  
Simulation Software ◽  
Dynamic Responses ◽  
Dynamics Simulation ◽  
Combined Effects ◽  
Vehicle Model ◽  
The Stability

A vehicle model and a movable-point simple turnout model were established, and the influences on dynamic responses caused by turnout irregularities when train passes through No.18 turnout was analyzed by using the turnout dynamics simulation software based on finite element method. It shows that turnout dynamic responses are influenced by the combined effects of various types of irregularities, which produce bigger dynamic response than single irregularity. In the turnout devise and use, the distance between slide plate and switch rail or nose rail should be as close as possible, the position arrangements of traction points should be optimized and the insufficient displacement should be eliminated as much as possible; No.18 turnout structure design is reasonable, which can ensure the safety and the stability when train passes over turnout.

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