Study On Vibration Control Technology For Deep Water Jack-up Offshore Platform

Deep water jack-up offshore platforms have large flexibility and work under poorconditions. Long-term and continuous environmental loads make platform structurevibrate more distinct and easy to induce structure damage, leading to its collapse.Therefore, the study of deep water jack-up offshore platforms’ vibration controltechnology has great significance.Having fully understood structure vibration control theory and technology, basedon linear wave theory and Morison equation, using spectrum analysis method tocalculate random wave force, the dynamic response characteristics of deep waterjack-up offshore platforms under random wave loads was analyzed. Then, present aMRFD semi-active control method based on BP neural network, and verified thismethod by both numerical simulation and model test. This paper mainly includes：1. Establish a deep water jack-up offshore platform structure vibration equation,give the time domain and frequency domain solution method respectively. Atypical deep water jack-up offshore platform was taken as the numerical exampleto simulate the vibration response of the platform. The vibration responsecharacteristics of the platform are given.2. Establish a deep water jack-up offshore platform structure vibration controlequation. Based on BP neural network, using MRFD as a semi-active controldevice, a deep water jack-up offshore platform structure vibration semi-activecontrol method was present. A typical deep water Jack-up platform was taken asthe numerical example to study the vibration control effect of proposed method.3. Taking a typical deep water jack-up offshore platform as the prototype, design adeep water jack-up offshore platform test model on the basis of the dynamicsimilarity criteria with scale of1:40, and the numerical simulation of neuralnetwork MRFD semi-active control method was done.4. The test model of the deep water jack-up offshore platforms and the neuralnetwork MRFD semi-active control system were made. Finished the model test in wave pool, studied the control effect under different cases of regular wave andrandom wave, and the test results was compared and analyzed.