Roghayeh Rezaei - student - university of tabriz
Mohammad Ali Lotfollahi - yaghin - professor - university of tabriz

This paper presents the results of a research on water level rise. Although there are different kinds of water level rise (tidal water level rise, water level rise due to seabed’s subsidence, water level rise because of storm surge) exerted on offshore structures, one special water level rise,which is due to global warming, is considered in this study. One Jacket offshore platform is modeled using ANSYS finite element software. It is supposed that this structure has beeninstalled in a medium water depth and the water level rise about 2.5 is exerted on this structure beyond its design water level. For evaluating the effect of design water level on the structural behavior after water level variation, three different models with three different design waterlevels is applied. For this purpose, Von Mises stress is used as an ideal criteria for evaluating steel structures serviceability. More detailed studying is done by assessing variation of utilization ratio because of water level variation. The results of this research show that depend on structuralelements location on the whole structure, different behaviors are possible. For some elements, water level rise causes to increase in Von Mises stress and consequently in Utilization Ration of these elements but for some others the results are vice versa

Jacket platform, Water Level Rise, Time history analysis, Utilization ratio, Von-Mises stress