A CFD-FEA coupled model for simulating dynamic response of offshore jacket platform under earthquake considering wind, wave, current and aftershock loads

Abstract

Offshore platforms as the key equipment in marine oil and gas exploitation are facing challenges from various environmental conditions, such as winds, waves, currents and even earthquakes. Due to the combined action of those concurrent loads, there is potential risk of accidents. The aim of this paper is to systematically study the dynamic response and safety assessment of the large scaled offshore structures against the concurrent loads considering the fluid-structure interaction (FSI) effects. Three-dimensional numerical wave flume including a jacket platform is established by CFD software Fluent, based on which the simulation of wave generation and propagation is carried out. Then the FSI effects between waves and platform are analyzed using the CFD- FEA coupling method. Subsequently, the seismic ground accelerations are inputted into the platform, correspondingly the structural response is analyzed. Moreover, multiple influencing factors including earthquake direction and mainshock-aftershock sequence are discussed. The results show that the structure response under concurrent loads is not a simple linear superposition of different load. The seismic response would be underestimated if wave action is ignored when the earthquake acts on certain angles. The methodology proposed could be regarded as an effective way to analyze the FSI problem under realistic offshore environment.