Rehabilitation of jacket offshore platforms using friction damper device and buckling restrained braces under extreme loads

Some existing platforms may have some problems with probable extreme future loads such as earthquake. From economic point of view, it is preferable to retrofit and continue using of existing jackets in many cases, in comparison to a new installation. Two efficient rehabilitation methods of friction damper device and buckling restrained braces are presented and investigated numerically for seismic loads from far-fault and near-fault earthquakes. As an example, an existing four-leg service platform placed in the Persian Gulf (Ressalat) is considered and the results are presented. Because of low redundancy in jacket platforms (after buckling of compression members), it is important to investigate the effect of friction damper device on the structural behavior. Buckling restrained braces solves the law redundancy because of no buckling and no decrease in strength. The results show the high efficiency of both methods in reducing structural responses and increasing seismic performance level. Such studies are very useful for many existing jacket platforms that their lifetime is to be extended.