scholarly journals Impact of Hydrodynamic Interaction Between Pontoons on Global Responses of a Long Floating Bridge Under Wind Waves

2018 ◽  
Author(s):  
Xu Xiang ◽  
Thomas Viuff ◽  
Bernt Leira ◽  
Ole Øiseth
Keyword(s):  
Hydrodynamic Interaction ◽  
Wind Waves ◽  
Vertical Motion ◽  
Interaction Effects ◽  
Viscous Damping ◽  
Interaction Coefficients ◽  
Wave Effects ◽  
Floating Bridge ◽  
Bridge Responses ◽  
The Time Domain

The hydrodynamic interaction between floating bridge pontoons and its impact on the bridge global responses are investigated in the current study. The global model for end-anchored floating bridge for Bjørnefjord crossing is modelled in ORCINA-OrcaFlex. Forty-six pontoons are used to support the bridge, with a centerline distance of 100m between two pontoons. Two models are setup for comparison: (1) The OrcaFlex model with hydrodynamic coefficients of pontoons without hydrodynamic interaction; (2) The OrcaFlex model with hydrodynamic interaction coefficients, which were calculated by ANSYS-AQWA. Firstly, a case study of hydrodynamic interaction effects on added mass, potential damping and diffraction force is given, showing that the piston and sloshing modes have strong correlation with the resonances. Then two sea states were run on the two models with and without hydrodynamic interaction effects. The first order wave effects are included in the analysis. The observed extremes of the time-domain bridge girder bending moments and motions were compared between two models. The comparison shows both reduction and increase of bridge responses depending on the wave directions. A sensitivity test of drag coefficients applied on the pontoon vertical motion is carried out as a rough examination of the neglected viscous damping on the hydrodynamic resonances. The viscous damping effects on the resonances should be further quantified.

Simulation of Time Histories of Second-Order Wave Effects by Pseudo-Linear Transformation

1995 ◽  
Vol 117 (2) ◽  
pp. 78-84
Author(s):  
Y. Li
Keyword(s):  
Dynamic Response ◽  
Time History ◽  
Second Order ◽  
Hilbert Transforms ◽  
Structural Dynamic ◽  
Quadratic Transformation ◽  
Wave Effects ◽  
Time Histories ◽  
Component Wave ◽  
The Time Domain

Simulation of the time histories of second-order wave effects is often performed by quadratic transformation of a wave time history. By the present approach, the quadratic transformation of waves is approximated by linear combinations of the products of component wave time records and their Hilbert transforms. The computational efficiency is greatly enhanced. The efficient quadratic transformation of a time history is for the time domain solution of structural dynamic response, and can also be used as a post-processor of the frequency domain solution for obtaining statistic parameters of dynamic response.

scholarly journals Hydrodynamic Interaction Effects on Wave Exciting Force in Large Scale Floating Structures

1993 ◽  
Vol 1993 (174) ◽  
pp. 243-251 ◽  
Author(s):  
Koichiro Yoshida ◽  
Hideyuki Suzuki ◽  
Noriaki Oka ◽  
Kazuhiro Iijima ◽  
Takuya Shimura ◽  
...  
Keyword(s):  
Large Scale ◽  
Hydrodynamic Interaction ◽  
Interaction Effects ◽  
Exciting Force ◽  
Floating Structures

Non-Dimensionalisation of Lateral Distances Between Vessels of Dissimilar Sizes for Interaction Effect Studies

2017 ◽  
Vol 159 (A4) ◽  
Author(s):  
N Jayarathne ◽  
D Ranmuthugala ◽  
Z Leong ◽  
J Fei
Keyword(s):  
Interaction Effect ◽  
Hydrodynamic Interaction ◽  
Interaction Effects ◽  
Full Scale ◽  
Correlation Technique ◽  
Effect Data ◽  
Scale Interaction ◽  
Model Scale ◽  
Interaction Studies ◽  
Lateral Distance

To date, most of the hydrodynamic interaction studies between a tug and a ship during ship assist manoeuvers have been carried out using model scale investigations. It is however difficult to establish how well results from these studies represent full scale interaction behaviour. This is further exacerbated by the lack of proven methodologies to non-dimensionalise the relative distances between the two vessels, enabling the comparison of model and full scale interaction effect data, as well as between vessels of dissimilar size ratios. This study investigates a suitable correlation technique to non-dimensionalise the lateral distance between vessels of dissimilar sizes, and a scaling option for interaction effect studies. It focuses on the interaction effects on a tug operating around the forward shoulder of a tanker at different lateral distances during ship assist operations. The findings and the non-dimensioning method presented in this paper enable the interaction effects determined for a given ship-to-tug ratio to be used to predict the safe operational distances for other ship-to-tug ratios.

Effect of the elastic hysteresis term formulation and response to non-harmonic periodic excitations of a non-linear SDOF dynamical model with weak frequency-dependency in the time domain

2021 ◽  
pp. 095440622110182
Author(s):  
Christos Spitas ◽  
Mahmoud S Dwaikat ◽  
Vasileios Spitas
Keyword(s):  
Correction Factor ◽  
Time Domain ◽  
Hysteresis Loops ◽  
Domain Model ◽  
Viscous Damping ◽  
State Variables ◽  
Hysteretic Damping ◽  
Vibration Responses ◽  
The Time Domain ◽  
Damping Model

We elaborate a SDOF time-domain model for elastic hysteretic damping, by modifying the viscous damping model to introduce an instantaneous correction factor that recursively depends on the state variables of the system, such that the response exhibits weak dependency on frequency, corresponding to a large array of engineering materials. The effect of different formulations for calculating the instantaneous correction factor on the predicted hysteresis loops and the potential manifestation of singularities is studied. Hysteresis loops anticipated by the model are plotted and forced vibration responses to harmonic and other periodic non-harmonic excitations are simulated and discussed, also in comparison to the conventional viscous and Reid’s damping models.

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