Optimized SMA Dampers in Vibration Control of Jacket-type Offshore Structures (Regular Waves)

Abstract

Article History: Received: 6 Dec. 2018 Accepted: 10 Mar. 2019 Undesired oscillations of jacket platform may influence the structural functionality and sometimes fatigue occurs. The main objective of this research is to control wave-induced vibrations of fixed jacket platforms with the use of optimized shape memory alloys dampers. To model the hysteretic behavior of SMA elements and performing dynamic analysis an efficient isothermal idealized constitutive model is developed in this research and direct integration time history analysis is carried out. Dynamic responses of multidegree of freedom system of jacket platform, with 90 m height and equipped with SMA dampers, is estimated and compared with the bare jacket. Furthermore, an optimization algorithm such as Ideal Gas Molecules Movements (IGMM) is implemented in this research to improve the efficiency of the dampers and minimize the deck displacements under the action of extreme wave. The results show that the optimized SMA dampers can improve the structural response by decreasing 47.5 percent of deck displacement, 56.5 percent of deck acceleration and finally 28 percent of base shear. In an SMA damper-equipped platform, reduced wave intensity will reduce the damper efficiency.