Low Frequency Vibration Control of the Offshore Fixed Platforms by Using Tuned Liquid Column Damper

Abstract

The offshore fixed platforms are confronted with greater wind and wave forces as their installation site moves toward the deep sea, so it is definitely necessary to reduce the low frequency vibration of structures for the safety and comfort of crews. The dynamic dampers are generally used to reduce vibration of structures. Especially, the tuned liquid column damper (TLCD) has been applied to reduce the low frequency vibration of onshore tall buildings. In this paper, the design procedure of TLCD is proposed to control the low frequency vibration of fixed platforms through the simulation and experiment with a small-scale model. The vibration control target is the surge motion of fixed platforms and the major design variables of TLCD are mass and damping ratios. The optimized design variables of TLCD are determined from the calculation of the amplification factor. In the experiment, the effects of mass and damping ratios are considered by changing the breadth of column, the opening ratio and number of the orifices. The results of experiment are found to well agree with the simulation. The 83% of structure vibration level can be reduced by applying the optimized TLCD.