Study of Vibration Control of Platform Structures

• Main Author: Ashley Waples
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Sea ice
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.549.702; http://people.clarkson.edu/projects/reushen/reu_china/Website/assets/participants_assets/Reports/Ashley.pdf

This paper discusses the vibrations induced by sea ice in off-shore oil platform structures. The mitigation of these vibrations through passive controls, specifically the tuned mass damper (TMD), is also explained. A single-degree of freedom model of the JZ20-2 MUQ oil platform under excitation was designed and validated using Simulink. Simulation of the actual platform structure in the Bohai Bay was used with a large-scale model of the passive control TMD for testing. This set-up is referred to as a half-experimental with half-simulation test. Experiments were conducted by applying four different forcing patterns with and without the TMD attached to the system. The four force types were a harmonic input, a determined ice-force, a random ice-force, and the ice-force time history function. These excitations were based upon the actual measured ice-force on the JZ20-2 MUQ oil platform structure in the Bohai Bay. They were first set to the natural frequency of the tuned mass damper and then other frequencies were applied to verify the assumed natural frequency. The results of the testing with and without the TMD were then compared to see the effectiveness of the TMD. Mitigation of vibrations from ice forces was shown through a reduction in displacement of the structure. There is still no reduction of acceleration in the structure with the passive control TMD; necessitating further testing, possibly with active or semi-active controls.