Page 348 - Practical Design Ships and Floating Structures

Practical Design of Ships and Other Floating Structures 323
You-Sheng Wu, Wei-Cheng Cui and Guo-Jun Zhou (Eds)
6 2001 Elsevier Science Ltd. All rights reserved

A DESIGN MODIFICATION OF VLCC WITH
WIDE WEB FRAME SPACE

Jae-Hyung Park, Chang-Hwan Jang and Joo-Ho Heo
Design Tech. R & D Team
Daewoo Shipbuilding & Marine Engineering Co.
1 Ajoo, Koje, KyoungNam, Korea

ABSTRACT
A new VLCC(Very Large Crude Oil Carrier) for improving productivity is suggested and the
development procedures for the new VLCC are introduced. In the stage of initial design, a new VLCC
with eight web frames and one swash bulkhead per one hold is suggested to reduce the number of web
frame. Longitudinal structural members having sufficient longitudinal strength are introduced through
conservative rule scantlings considering design still water bending moment and wave bending moment.
3-D cargo tank F.E. analyses have been performed to assess the structural adequacy of primary
structural members such as floors, transverse webs, transverse bulkheads, swash bulkheads, girders
and longitudinal bulkheads.
In the viewpoint of fatigue strength, hopper knuckle structure is apt to be weakened by opening and
closing modes due to internal dynamic pressures and dynamic sea pressures. The fatigue strength of
longitudinal connection is critical because the combined local stress components due to simultaneous
internal and external pressure loads are to be added to the global stress components induced by hull
girder wave bending. With these reasons, fatigue strength is calculated in longitudinal connection and
hopper knuckle connection of the modified structural arrangement. The collision resistance is also
investigated by comparing the new VLCC design and the original VLCC design.
Through this research, the newly designed VLCC is found to have enough strength with regard to
yielding criteria, structural stability, fatigue strength and collision capacity.

KEYWORDS
Wide web frame space, Longitudinal strength, Hopper knuckle, Fatigue, Collision

1 INTRODUCTION

In the design of vessel, it is dificult to satisfy both aspects simultaneously, long-term operation life
with minimum maintenance costs and structural design with the economic ship building costs.
Many research activities have been carried out for the development of new VLCC which has the long-
term operation life and simple maintenance faculty in line with economical structural design [Park, et