Sensitivity analysis on seismic life-cycle cost of a fixed-steel offshore platform structure

In this study sensitivity analyses were conducted to investigate the relative importance of different uncertain variables on the life-cycle cost (LCC) estimation of a steel jacket offshore platform subjected to seismic loads. The sensitivity analysis was conducted using different methods such as tornado diagram analysis (TDA), first-order second-moment (FOSM) and Latin hypercube sampling (LHS). The analysis results showed that the uncertain variables related to loss estimation and seismic hazard had a more dominant influence on the LCC variability compared to the other variables. Among the structural uncertain parameters, the variability in plastic hinge strength and modal damping ratio had the most significant impact on the LCC. Variability in the initial cost showed higher impact on LCC estimations compared to other cost component variables. It was also observed that the application of members with energy dissipation capability resulted in more economical design compared to use of conventional members.