Long-term stochastic extreme response analysis of floating bridges

For the assessment of extreme responses needed in design of marine structures, a full long-term analysis is recognized as the most accurate approach. However, due to the very large number of structural response analyses traditionally needed for this approach, the computational effort is usually considered to increase above acceptable levels for complex structures such as floating bridges. This paper shows that the first and second order reliability methods (FORM and SORM) found in connection with structural reliability analysis can be used in an inverse manner to efficiently obtain approximate solutions for the full long-term extreme response of structures subjected to environmental loads, and this is demonstrated for floating bridges. Very accurate results are obtained using a limited number of short-term response calculations, and by applying a fast calculation method for the short-term stochastic response, full long-term extreme responses are calculated for two different pontoon floating bridges.