Seismic reliability analysis of offshore fixed platforms using incremental dynamic analysis

It is generally accepted that performance-based design has to be reliability-based. Seismic performance evaluation is based on nonlinear dynamics and reliability theory taking into account uncertainties during analysis. Considering the economic importance of jacket type offshore platforms, the present research aims to assess the seismic performance of offshore steel platforms. In this study, three platforms located in the Persian Gulf were modeled using three dimensional structural modeling tools. Each platform was modeled and analyzed using both rigid and pinned connections. Reliability analysis was performed in accordance with Federal Emergency Management Agency (FEMA) guidelines using the results of incremental dynamic analysis for the three platforms. The results showed that platforms possessing rigid connections provide the desired confidence level of FEMA for the performance level of collapse prevention while only one platform with pinned connections was able to provide the desired confidence level.