NONLINEAR SEISMIC SOIL-PILE-STRUCTURE INTERACTION ANALYSIS OF JACKET TYPE OFFSHORE PLATFORMS USING FIBER ELEMENTS

Nonlinear dynamic analysis for offshore structures has been a major challenge in marine structural and earthquake engineering. In this paper, nonlinear dynamic analysis of jacket type offshore platforms considering soil-pile-structure interaction subjected to strong ground motion have been performed. In this paper, nonlinear three-model of jacket and piles have been considered using fiber element (FE) and beam on nonlinear winkler foundation (BNWF) approaches respectively in an integrated model. Both jacket and pile elements have been modeled using fiber cross-sections. In this paper, free field ground motion analysis with respect to bedrock excitations has been done using nonlinear stress-strain relations for soil. This model has been developed using Open System for Earthquake Engineering Simulation (OpenSEES) software. In this paper, nonlinear seismic response analysis of an existing sample offshore platform in Persian Gulf subjected to different levels of earthquake has been performed and the results in terms of topside displacement, maximum drift in intermediate level of jacket, pile responses have been presented.

Keywords:

nonlinear , seismic response , offshore platforms , BNWF , Fiber element , pile-soil-structure interaction , fiber cross-sections