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ABS has developed an offshore structural assessment program specifically designed for semisubmersible drilling rigs.

The ABS Eagle Offshore Structure Assessment Program (OSAP) allows designers to more easily check their designs against ABS MODU Rules to confirm they meet classification requirements.

Evaluating dynamic loads, hull strength and site-specific fatigue assessments are keys to developing appropriate design criteria for semisubmersibles. The ABS program consists of three main functions: design wave calculation; global strength assessment; and buckling and ultimate strength evaluation.  

The program is open and flexible, meaning that the software’s architecture can easily interface with other commercial design software. 

“Multiple assessments can be carried out once the fatigue, buckling and global strength data is entered. The designers can verify the structure meets ABS class requirements,” said Pao-Lin Tan, Manager, ABS Corporate Research & Product Development.

Highlights of the software’s capabilities include: vessel motions and wave data entered into the program create the wave’s associated critical response forces and accelerations; design waves and vessel response amplitude operators (RAOs) can be graphically depicted to facilitate the selection of rational loads for hull strength assessment; degrees of pitching, rolling and yawing can be graphically depicted; and yielding, buckling and fatigue checks in accordance with the ABS MODU Rules can be performed with the results graphically depicted.

Given current industry demand for semisubmersibles the program has been enthusiastically received. More than 100 offshore engineers from leading companies in and around Houston, Texas, attended a recent seminar by ABS and software simulation firm ANSYS, Inc. to demonstrate OSAP.

During the seminar, attendees were able to preview the interactive graphic user interface (GUI) which allows them to zoom, pan, clip and rotate finite element models and navigate to specific areas of interest and to query various structural elements such as shell, beam or pipe, independently or collectively as predefined sets.