Analysis On Dynamic Characteristic Of Floating Platform Based On Prototype Monitoring

Motion response of floating platform in deep water is an important reference for the structural design and security guarantees. Due to the complexity of characterizations of the ocean-environmental load, together with nonlinearity and parameter assumptions in hydrodynamic numerical modeling and model test, there still exist uncertainties and challenges in the design and operation of floating platforms. Especially under the extreme load conditions, the platform will withstand unpredictable environmental loads acting on it, and errors caused between analysis and actual results for the core indicators. Larger error will bring a severe test for the long-term reliable operation. Thus, carrying out prototype measurements with the service of marine floating structure can provide lots of references on the analysis of response characteristics of floating structure motion in deep water.The paper carried out the motion characteristic analysis based on synchronous prototype monitoring information of ocean environmental parameters and floater motions in a semi-submersible platform in South China Sea. The relationship between the measured wave spectrum and JONS WAP spectrum is discussed. The spectral shape parameters of JONS WAP spectrum are present via the monitoring information in South China Sea. RAOs(Response Amplitude Operator) of floater at different wave angles (such as 0°,30°,and 90°) are obtained by synchronous analyzing of wave loading and motions of floating structures. The method is improved by EMD (Empirical Mode Decomposition), a typical analysis method which is evaluated on the design specifications of floating structure under the irregular wave. In order to analyze the effect of motions of the floater in harsh condition, the motions analysis (roll, pitch, and heave) of floating structure is performed in frequency domain based on spectrum analysis during typical typhoons. The spectral characteristic value is calculated by discrete Fourier transformation. The typhoon management methodology is proposed to the semi-submersible platform in South China Sea, which can predict the motion response in the extreme condition and provide security warning.