The use of seismic isolation with the method of finite element to reduce vibrations caused by the earthquake in the offshore platform

摘要

In this paper, with using Lead Rubber (LR) isolation system, the performance of the offshore platform is evaluated under earthquake excitation. LRIs are known isolators in structural control systems which dissipate the imposed energy at isolation level. For this aim, time history analysis method has been used for seismic assessment of the offshore platform in Persian Gulf location. Nonlinear finite element method is utilized for simulation of the structure in ANSYS software. Because of consideration the randomness nature of ground motions, four earthquakes (ElCentro (1940), Kocaeli (1999), Manjil (1990) and Kobe (1995)) have been studied as the imposed excitation. Engineering Demand Parameters (EDPs) such as displacement and acceleration of deck are compared in both unisolated and isolated state. The results of this study show the application of isolation systems is a practical solution for reducing the seismic and dynamic loads on the jacket.