سال انتشار: ۱۳۸۵
محل انتشار: هفتمین همایش بین المللی سواحل، بنادر و سازه های دریایی
تعداد صفحات: ۶
S.A.Kheiri – Ms Graduate of Marine Structure, Faculty of Civil Engineering, University of Tehran
M.R.Bahaari – Ms Graduate of Marine Structure, Faculty of Civil Engineering, University of Tehran
An existing platform should undergo the assessment process if one or more of the following conditions exist: 1) Addition of personnel 2) Increased loading on Structure 3) Damage found during inspection and etc. A structure should be evaluated based on its current status, accounting for any damage, repair, or other factors affecting its performance. Analyses consist of both design level analysis and ultimate strength analysis. The latter is more desired and common in offshore work. Push-over and nonlinear time-domain analysis methods are acceptable in ultimate strength analysis. The main result of such analysis is Reserve Strength Ratio (RSR). Acceptance or rejection of structure fitness is dependant on this ratio. In conventional pushover analysis, wave dynamic loading is simulated by equivalent quasi static load and dynamic affects such as added mass, damping and inertial force are neglected. However, in timedomain analysis, dynamic effects are considered and subsequently ultimate strength can be estimated better with more precision. In this current study, two platforms were selected for case study analysis. Push-over analyses and nonlinear dynamic analyses were applied to both platforms and the relevant results were compared to each other. "ABAQUS" software was used for modeling and analysis. Pile-soil interaction is modeled by nonlinear springs and in the meantime analyses took into account the effect of large displacement, plasticity and strain hardening, as well. In the course of limited investigation, it was concluded that in nonlinear dynamic analysis, reserve strength of jacket structures was estimated to be higher than that of static push-over and that structures can bear more partial failure before global failure.