Hydroelastic response analysis of pneumatically supported floating structures using a BEM-FEM coupling method

2016 ◽  
Vol 20 (7) ◽  
pp. 2875-2884 ◽  
Author(s):  
Sanghyun Hong ◽  
Jong Seh Lee
Keyword(s):  
Coupling Method ◽  
Response Analysis ◽  
Floating Structures ◽  
Hydroelastic Response

Hydrodynamic Behavior of Truss Pontoon Mobile Offshore Base Platform

2016 ◽  
Author(s):  
Somansundar Sakthivel ◽  
Panneer Selvam Rajamanickam ◽  
Nagan Srinivasan
Keyword(s):  
Bending Moment ◽  
Offshore Structures ◽  
Elastic Behavior ◽  
Response Analysis ◽  
Vertical Acceleration ◽  
Floating Structures ◽  
Operational Conditions ◽  
Box Structure ◽  
Mobile Offshore Base ◽  
Hydroelastic Response

Very Large Floating Structures (VLFS) are highly specialized floating structures with variety of applications ranging from airport strips to floating motels offshore ports etc. Their economic design is based on their hydro-elastic behavior due to wave environmental forces. VLFS are extra large in size and mostly extra long in span and for that reason they are mostly modularized into several smaller structures and integrated. VLFSs may be classified into two broad categories, namely the semi-submersible type and the pontoon-type. The former type of VLFSs having their platform raised above the sea level and supported by columns resting on submerged pontoons and can minimize the effects of wave actions. In open sea, where the wave heights are relatively large, the semi-submersible VLFSs are preferred. On the other hand, the pontoon-type VLFS is a simple flat box structure floating on the sea surface. It is very flexible compared to other kinds of offshore structures, and so its elastic deformations are more important than their rigid body motions. The critical problem is the longitudinal bending moment of the long floating vessel in waves/current environment. Most of the present available VLFS designs are not economical for applications in hostile ocean. This paper presents hydrodynamic analysis carried out on an innovative VLFS called truss pontoon Mobile Offshore Base (MOB) platform concept proposed by Srinivasan [1]. The concept uses a strong deck with strong longitudinal beams to take care of the needed bending moment of the vessel for the survival, standby and operational conditions of the wave. At the submerged bottom just above the keel-tank top, a simple open-frame truss-structure is used instead of a heavy shell type pontoon. Thus the truss-pontoon provides the necessary flow transparency for the reduction of the wave exciting forces and consequently the heave motions and the vertical acceleration. Numerical analysis of truss pontoon MOB platform is carried out using HYDroelastic Response ANalysis (HYDRAN). Responses of the isolated scaled module in waves are obtained from these numerical tools and compared with published literature. Unconnected two modules and three modules are analysed using HYDRAN and the responses are compared with the isolated module. The proposed concept yielded lesser responses as compared to semisubmersible conventional MOB platform.

Literature Review of Methods for Mitigating Hydroelastic Response of VLFS Under Wave Action

2010 ◽  
Vol 63 (3) ◽  
Author(s):  
C. M. Wang ◽  
Z. Y. Tay ◽  
K. Takagi ◽  
T. Utsunomiya
Keyword(s):  
Literature Review ◽  
Experimental Methods ◽  
Wave Action ◽  
Oscillating Water Column ◽  
Floating Structures ◽  
Mechanical Joints ◽  
Hydrodynamic Response ◽  
Air Cushion ◽  
And Performance ◽  
Hydroelastic Response

Presented herein is a literature review on the design and performance of antimotion structures/devices such as breakwaters, submerged plates, oscillating water column breakwaters, air-cushion, auxiliary attachments, and mechanical joints for mitigating the hydroelastic response of very large floating structures (VLFS) under wave action. Shapes of VLFS that could minimize the hydrodynamic response of the structure are also discussed. The analytical, numerical, and experimental methods used in studying the effect of these antimotion structures/devices toward reducing the hydroelastic responses of VLFS are also reviewed.

Very Large Floating Structures

2007 ◽  
Author(s):  
H. Suzuki ◽  
H. R. Riggs ◽  
M. Fujikubo ◽  
T. A. Shugar ◽  
H. Seto ◽  
...  
Keyword(s):  
Design Procedure ◽  
Offshore Structures ◽  
Floating Structure ◽  
Floating Structures ◽  
Design Procedures ◽  
Novel Technology ◽  
Hydroelastic Analysis ◽  
Behavior Design ◽  
Hydroelastic Response ◽  
Near Future

Very Large Floating Structure (VLFS) is a unique concept of ocean structures primary because of their unprecedented length, displacement cost and associated hydroelastic response. International Ship and Offshore Structures Congress (ISSC) had paid attention to the emerging novel technology and launched Special Task Committee to investigate the state of the art in the technology. This paper summarizes the activities of the committee. A brief overview of VLFS is given first for readers new to the subject. History, application and uniqueness with regard to engineering implication are presented. The Mobile Offshore Base (MOB) and Mega-Float, which are typical VLFS projects that have been investigated in detail and are aimed to be realized in the near future, are introduced. Uniqueness of VLFS, such as differences in behavior of VLFS from conventional ships and offshore structures, are described. The engineering challenges associated with behavior, design procedure, environment, and the structural analysis of VLFS are introduced. A comparative study of hydroelastic analysis tools that were independently developed for MOB and Mega-Float is made in terms of accuracy of global behavior. The effect of structural modeling on the accuracy of stress analysis is also discussed. VLFS entails innovative design methods and procedure. Development of design criteria and design procedures are described and application of reliability-based approaches are documented and discussed.

Dynamic Response of SPAR in Internal Solitary Waves

2011 ◽  
Author(s):  
Yan Qu ◽  
Zhijun Song ◽  
Bin Teng ◽  
Yunxiang You
Keyword(s):  
Dynamic Response ◽  
Solitary Waves ◽  
Mkdv Equation ◽  
Internal Solitary Waves ◽  
Response Analysis ◽  
Potential Hazard ◽  
Current Profile ◽  
Floating Structures ◽  
Dynamic Motion ◽  
De Vries

Internal solitary wave is considered as a potential hazard environmental condition to the floating structures in South China Sea. This paper presents results of the dynamic response analysis of a SPAR in internal solitary waves (ISW). Mathematical model of the ISW is selected to simulate the current process induced by the ISW. The result shows that the Korteweg–de Vries (KdV) gives rational result compared with the Modified Korteweg–de Vries (MKdV) equation. Dynamic motion of SPAR were estimated by using the current profile derived from KDV theory, load determined by Morrison equation and the nonlinear model of the mooring system.

Wave Response of a Semisubmersible Floating Structure Model With Mechanical Connectors

2008 ◽  
Author(s):  
Yoshiyasu Watanabe ◽  
Koichiro Yoshida
Keyword(s):  
Numerical Analysis ◽  
Response Analysis ◽  
Structure Model ◽  
Analysis Program ◽  
Floating Structure ◽  
Response Characteristics ◽  
Wave Response ◽  
New Type ◽  
Hydroelastic Response ◽  
Two Bodies

It is desired instead of welding to develop a mechanical connector, which may work well to connect two units at the site in spite of circumstances of some extent of relative motions between two units caused by waves. One of the authors proposed a new type of mechanical connector, which is based on an idea of three bodies problem instead of usual mechanical connectors (two bodies problem). In this paper, wave exciting tests of a semisubmersible floating structure model with the proposed mechanical connectors of 1/100 scale and the numerical analysis using hydroelastic response analysis program VODAC are carried out and wave response characteristics of the semisubmersible floating structure model with the mechanical connectors and its feasibility are reported.

Influence of hinged conditions on the hydroelastic response of compound floating structures

2015 ◽  
Vol 101 ◽  
pp. 12-24 ◽  
Author(s):  
Cunbao Zhao ◽  
Xiaochen Hao ◽  
Ruifen Liang ◽  
Jiuxi Lu
Keyword(s):  
Floating Structures ◽  
Hydroelastic Response
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