Damage Identification Of Offshore Platforms And The Positioning Method And Model Test Study

Many disadvantages such as environment corrupting, scouring and base dynamic softening, material ageing, component defect, mechanism damage and so on, will cause the damage of the component of offshore platforms and the whole resistance attention; and then affect degree of structure safety and durability. Once the accident happens on offshore platforms, it will bring a horrendous lose of life and property, therefore, in order to timely and accurate access to offshore platform damage and degree of damage information, using structural damage detection technologies for offshore platform structural damage identification and localization has important theoretical significance and a good application prospects. The paper's major research concludes:1. Compute the random wave force acting on the offshore platform finite element model using linearized Morison equation, and establish motion equations of offshore platforms in the random wave loads, and the solving method of offshore platform structure in random vibration response under wave action is given from the perspective of the time domain.2. Using Daubechies wavelet transform analysis, singularity detection of the singular points and irregular parts of mutations in acceleration response signal is achieved. On this basis, a real-time damage identification method of offshore platform is developed. A typical offshore platform as numerical example, the damage identification effect analysis of platform structure in cases of different damage location and different noise with wavelet transform was given.3. Analyse the structural acceleration response signal with wavelet packet, and extract the eigenvector that containes structural damage information. And the wavelet packet node energy change can determine the damage location progressively as the BP network input vector. In this paper, a three-step damage localization method of offshore platforms is developed based on wavelet packet node energy change and neural network, and the effect analysis of three-step method of the offshore platforms is carried out in different damage conditions.4. In this paper, on the basis of similarity criterion on dynamics, the platform model was designed with the scale of 1:50 by a typical jacket platform. And the acceleration response experiments are carried out on the shore and in the pool in many different test conditions and different damage locations. Using the three-step method of this paper, identify and locate the damage of the platform model based on the model test results of the platform model in different working conditions, and the feasibility and applicability of the method were tested.