Vibration control of jacket offshore platforms subjected to irregular wave loads using damping isolation system

Using control tools is one of the efficient methods to reduce the responses of marine structures. The use of dampers in jacket marine structures can help to reduce the dynamic response of the structure with increasing damping and without changing the structural stiffness. In this research, for vibration control of the Resalat oil platform in the Persian Gulf under irregular wave loads, rubber bearing base isolation system along with viscous dampers are utilized. The Morison equation is used for wave force formulation, as well as to model the time history of irregular waves, Jonswap spectrum is utilized. In this study, rubber bearing base isolator with three different effective damping ratios and viscous damper with different damping coefficients were used to investigate the effect of each control tool on structural responses. In addition, to achieve the optimal response, the structure studied in two different conditions; the structure with rubber bearing isolator, and the structure with rubber bearing isolator plus viscous dampers. The results showed that the use of rubber bearing isolator with viscous damper has a better performance on the jacket platform response. It also reduced the base shear of the structure, which could lead to a reduction in the cross-section of the piles.