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Statistical Design of Fender For Berthing Ship
Ueda, Shigeru (Tottori University) | Hirano, Toshihiko (Tottori University) | Shiraishi, Satoru (Independent Administrative Port and Airport Research Institute) | Yamamoto, Shuji (Independent Administrative Port and Airport Research Institute) | Yamase, Seigi (Bridgestone Corporation)
ABSTRACT Fender is commonly used for the purpose to absorb berthing energy and to decrease impact of berthing ship. Ship's berthing energy is proportional to virtual mass of ship and square of approach velocity, however it was reduced by rotational motion caused by eccentric berthing. Currently, fender is designed by calculating berthing energy for the maximum size ship and/or standard size ship considering ship mass, virtual mass factor, design approach velocity and eccentricity factor. Then select suitable fender to absorb ship's berthing energy. Recently, ship size increases so fast. For instance, size of modem container ships became more than 100,000 DWT. At some port, no berth is constructed to meet above those ships in full laden. As the result, ships larger than design ship is to be obliged lightening its draft at berthing. Even if the berth water depth is secured, virtual approach velocity must be decreased than design approach velocity. Some of the present authors had attempted to design a fender for berthing ship by means of statistical method and presented the results of the analysis to the llth ISOPE (Ueda and et al 2001). While in the previous paper, the probability of failure and safety factor on fender design for container ships were calculated, in this paper, analysis was made for conventional cargo ships by use of statistical data of arriving ships in some major port in Japan. 1. INTRODUCTION When ships berth for loading and unloading, fender is used for the purpose to absorb berthing energy and to decrease impact of berthing ship. Ship's berthing energy is calculated for the maximum size ship and/or standard size ship considering ship mass, virtual mass factor, design approach velocity and eccentricity factor. But ship size is generally registered by dead weight tonnage (DWT) for container ships, cargo ships and others.
- Transportation > Marine (1.00)
- Transportation > Freight & Logistics Services > Shipping (1.00)
Response Analysis Method of VLFS In Coastal Area Considering Topographical Effects On Wave Deformations
Iijima, Kazuhiro (Offshore Structures Division, Independent Administrative Institution, Port and Airport Research Institute) | Shiraishi, Satoru (Offshore Structures Division, Independent Administrative Institution, Port and Airport Research Institute)
ABSTRACT It is expected that VLFS (Very Large Floating Structure), especially pontoon type, will be installed in coastal areas. In coastal areas, wave deformations may play an important role. This means that we need to consider wave deformations due to topography when analyzing hydroelastic and hydrodynamic response of VLFS in coastal areas. Here, wave deformations include both linear phenomena and non-linear phenomena, such as reflection, shoaling, wave breaking, etc. In this paper, an approximate analysis procedure considering these wave deformations, whether they are linear or nonlinear, is proposed. The results by numerical analysis method are compared with the experimental results. In the experiment, reef model was examined. It is shown that the good estimation can be obtained through the procedure. INTRODUCTION Many researchers have proposed numerical analysis method for the prediction of response of VLFS (Very Large Floating Structure) in waves. Most of the proposed methods are based on linear theory and it seems that they have been applied only to such cases as nonlinear effects have less effects on the response of VLFS. However, considering that pontoon type VLFS is likely to be installed in coastal areas, wave deformations both linear and nonlinear must be considered in the analysis of VLFS since topographical factors give much effects on wave deformations. Here, the topographical factors are classified from the viewpoint of linearity. Wave reflections at quays or breakwaters are linear to incident wave and they can be included in the numerical analyses of response of VLFS developed and proposed so far. Ohmatsu (1998), Seto (1998), Utsunomiya (1998) and Nagata (1998) have proposed such a numerical mothod in which diffractions from breakwaters are considered as well as those from VLFS. Other effects are shoaling. Refraction should be theoretically considered in the response analysis of VLFS since it may cause linear effects.
Elastic Response of a Very Large Floating Structure In Waves Moored Inside a Coastal Reef
Shiraishi, Satoru (Offshore Structures Div., Independent Administrative Institution, Port and Airport Research Institute (PARI)) | Iijima, Kazuhiro (Offshore Structures Div., Independent Administrative Institution, Port and Airport Research Institute (PARI)) | Yoneyama, Haruo (Offshore Structures Div., Independent Administrative Institution, Port and Airport Research Institute (PARI)) | Harasaki, Keitaro (Ecoh Corporation)
ABSTRACT This paper describes the results of hydraulic model tests to determine the elastic response and mooring forces of a very large floating structure (VLFS) moored inside a coastal reef. The distribution of strains and vertical displacements due to the elastic response of the VLFS were measured in hydraulic model tests. The response characteristics were significantly affected by non-linear deformed waves inside the reef. INTRODUCTION Very Large Floating Structures (VLFS) that are moored at sites protected from ocean waves by breakwaters have been studied over the past several years (Inoue, 1999; Isobe, 1999; Sueoka, 2000). In this concept, a huge pontoon-type floating structure is moored by a mooring system such as mooring dolphins and fenders in a calm sea area, in which the wave height is reduced by a breakwater constructed near the floating structure. New studies were carried out in 2000 and 2001 to develop a new concept of VLFS with financial support from the Program for the Promotion of Fundamental Transport Technology Research from the Corporation for Advanced Transport & Technology (CATT). The new types of VLFSs are the semi-submersible type VLFS (Yoshida, 2001), a VLFS using submerged plates (Takaki, 2001), the echo-float (Ohmatsu, 2001) and VLFS moored inside a reef (Tori-i, 2001-l). The research on VLFS constructed inside a reef was carried out in cooperation with a university (Utsunomiya, 2001) and private companies (Torii, 2001–2) to develop a design method for constructing VLFS inside a reef. Wave height should be significantly reduced inside a reef by breaking of the wave, so a floating structure was moored inside of a reef without a breakwater in the concept studied. Wave deformation is very complicated inside of a reef compared to behind a breakwater due to non-linear effects, such as waves breaking in very shallow water.