Arefe Emami - Faculty of Civil Engineering, Sahand University of Technology, Tabriz, Iran
Ahmad Reza Mostafa Gharabaghi - Faculty of Civil Engineering, Sahand University of Technology, Tabriz, Iran

In this paper, the attempt has been made to analytically solve the coupling problem of a monochromatic linear wave with a semi-submersible platform which is modifiedby attaching Poro-Elastic Plates (PEPs) at the bottom of its pontoons. The PEP is considered to be homogenous, isotropic and saturated. The region around the semi-sub isdivided into different parts and their related governing equations with appropriate boundary conditions (BC s) are developed. By applying Eigenfunction Expansion Method(EEM), these equations with their related BC s for each region are solved numerically. In order to verify the developed model, it is applied to a typical GVA4000 semisubmersibledrilling rig and its heave Response Amplitude Operator (RAO) is extracted and compared with available experimental data. Furthermore, the PEP is attached to therig and its heave RAO is estimated and compared with the original case. It is concluded that using PEP reduces the peak value of the heave motion response as well as theresonance frequency. Therefore, it can be a suitable method in order to improve the performance of a semisubmersibleplatformparticularly its heavemotion response.