Concerning the potential risk of a semi-submersible structure, the Digital Twin technology was widely considered for the structural safety assessment. Directly measurement of the stress responses could be mostly accurate but quite difficult for installation of the sensors, due to the complexity of the structure and environment loads. In this paper, a method was introduced for structural safety assessment of a deep-water semi-submersible platform. Combining the field measurement and numerical simulation of the structural stress on specific locations, corrections of the stress response transition operator (RTO) on two locations can be found. We could then modify the numerical model by integrating correction coefficients from field measurement. To demonstrate the proposed method, a semi-submersible platform in the South China Sea was applied. The stress on 5 locations were measured with a duration of 15 days. To extend sample of sea states, 1428 short-term cases were obtained by using time-stepping approach. It is found that the RTOs between measured points have approximately stable relationships. The relative error between calculated result and measured value is less than 10%, indicating the strong potential for the digital twin application.
The structural safety assessment of offshore platform has always been the focus of the industry, and numerical simulation is the main calculation method. With the development of measuring technology and data transmission technology, it is very possible to use digital twin technology to evaluate the structural safety of offshore platforms. At present, there is no unified definition of digital twin. An acceptable definition is "to make full use of data such as physical model, sensor update and operation history, integrate multi-disciplinary, multi physical quantity, multi-scale and multi probability simulation process, and complete mapping in virtual space, so as to reflect the whole life cycle process of corresponding physical equipment." The concept of digital twin originated during the period of Apollo program in the United States and has been developed in three stages.
