Dynamic Response Analysis Of Multi-point Moored Crane Ship Under Operating Conditions

The ocean is a treasure house of resources far from being fully exploited and utilized by human beings and has become an important exploration field.As a special ocean engineering ship,crane ship is specially used for lifting operations on the water,and it is an indispensable engineering technology equipment in ocean construction.Compared with ordinary ships,large crane ships not only have significant differences in structural dimensions,but also have a significant impact on the stability of the hull due to the large short-term displacement and rapid changes in the center of gravity during operation.Large cranes operating offshore will be affected by the combined effects of wind,wave and current,and must adopt the multi-point mooring system for fixed positioning to ensure the stability and safety of the operation.Compared with static response,dynamic response analysis of mooring system fully considers the inertia force and fluid towing force of mooring cable,so dynamic characteristics analysis of multi-point mooring crane ship can be more accurate and meet the needs of engineering.In this paper,the coupling model of 1500 t crane ship and mooring cable was established,and the following aspects were studied:(1)Theoretical basis of multi-point mooring and positioning system for crane ship.It mainly includes the general situation of multi-point mooring and positioning system of crane ship,the types of mooring cables and the preliminary calculation of the main characteristic parameters,the basic design process of multi-point mooring and positioning system of crane ship,the types and calculation methods of environmental load and the common analysis software.(2)Time-domain analysis of crane ship mooring system.The dynamic response analysis of mooring cables and hull motion response,taking into account the stern lifting,side lifting,and storm self-storage conditions of crane ships in practical operation,is conducted in accordance with the environmental conditions of the North Pacific Ocean.This analysis takes into account the varying water depth conditions and wave direction angles,as well as the combined action of wind,wave,and current.(3)Failure analysis of crane ship mooring cable.By nonlinear curve fitting,the windward area of the articles is estimated.In the time domain,by analyzing the dynamic characteristics of the hull-mooring cable coupling model,the force of the remaining mooring cables and hull motion response are studied when a single mooring cable fails at a specific time under the combined action of wind,wave and current when the boom is lifted by stern,75 °and side.