This study carries out a dynamic analysis of the installation operation using offshore cranes in an ocean environment. The analysis is based on multibody dynamics considering various types of external forces, such as wave, wind and current in an ocean environment. The target operation is an installation of offshore structure using dual offshore cranes in the ocean. During the operation, two offshore cranes lift, turn over, and install offshore structure. The motions of offshore structure and the loads acting on the wires from the analysis were verified by comparing with the model test.
Offshore cranes are essential for heavy equipment related offshore operations such as offshore plant and subsea equipment installation. As offshore operations take place in extreme environments, the weight of the equipment targeted at sea operations is increasing. Thus, to overcome this, operations may be carried out using large offshore crane or multiple offshore cranes as shown in Fig. 1.
Large offshore cranes are advantageous in that they can lift heavy objects by using one offshore crane, but they are influenced by the movement conditions of the offshore crane and the seabed conditions of the offshore installation for mooring. Therefore, if it is difficult to perform an operation with a large offshore crane, it is necessary to perform a combination operation using several smaller offshore cranes. In the case of combination operation using multiple offshore cranes, there is a need to synchronize the operation of two or more cranes, which reduces the safety of the operation compared to using one offshore crane. Therefore, we must perform an analysis to confirm the stability of the operation in advance.
In this paper, we have developed a simulation for offshore installation operation based on a prototype of an integrated framework for evaluating and verifying stability to prepare marine operations using multiple cranes. The developed prototype confirms the problems that may happen in the offshore operation process using multiple crane such as crane collision, disconnections of wire rope due to excessive dynamic load, and position fixation of crane barge due to mooring design error. To apply various offshore tasks in the future, the framework extensibility is considered. To this end, a framework is designed to expand and reduce functions using a plug-in modular design.
