Many offshore platforms have been built up with the development of ocean projects. However

most of offshore is located in the seismic region and the platforms are easily to be seriously damaged by earthquake. Hence

the anti-earthquake design has always been a major part of research on the offshore platforms. The inclusion of vibration absorbers in the offshore platform can be an attractive method of mitigating the seismic responses.Vibration absorbers can be categorized as either active or passive. Tuned mass damper（TMD）

both passive and active

have been found to be effective in reducing the response of structures subjected to dynamic loads since 1970 s. Tuned mass dampers have been installed in quite a few tall buildings and structures including the Sydney Tower and Chifley Tower in Sydey. The dampers that depend on liquid motion to absorb and dissipate vibration energy

such as tuned liquid dampers （TLD） and tuned liquid column dampers （TLCD） have also been proposed for suppressing structural vibration. Tuned liquid column damper （TLCD） as a passive control device can suppress the structural vibration by the motion of liquid in a column container. The potential advantages of liquid vibration absorbers include: low manufacturing and installation costs; the ability of the absorbers to be incorporated during the design stage of a structure

or to be retrofitted to serve a remedial role; relatively low maintenance requirements; and the availability of the liquid to be used for emergency purposes

or for the everyday function of the structure if fresh water is used.In this paper

the control method for fixed offshore platform using semi-active tuned liquid column damper （TLCD） is presented. The equation of motion for platform-TLCD control system is given and the semi-active control strategy is established. A back propagation Artificial Neural Network （ANN） is used to adjust the orifice opening of TCLD because of the nonlinear motion of liquid in TLCD. The effectiveness of the control method is verified by the numerical examples. The following conclusions according to above studies are drawn as;（l）The vibration can be effectively suppressed with semi-active TLCD installed on the platform.（2）It can avoid the complicated non-linear computation of TLCD and save the calculation time by replacing the control criterion with the ANN and the effectiveness of control is much better.（3）TLCD has the advantage of simplicity

low cost

easy handling

and it is also an economical and effective control device for offshore platform.