Nonlinear dynamic structural optimization of offshore structures using equiv- alent static models

Resumo

Nonlinear dynamic analyses of offshore structures are well-known for their often expensive computa-
tional cost. Optimizing such models is an even more complex task because it requires many nonlinear dynamic

analyses in sequence. On the other hand, nonlinear static analyses of offshore structures have significant lower
computational cost, and can be used to approximate the nonlinear dynamic nature of the original problem and
come up with a valid optimized solution. This work proposes the use of an equivalent static model to perform
structural optimization applied to anchor systems of offshore structures. The equivalent static model is built based

on the field of displacement of the original model, using a penalization factor to approximate the static displace-
ments field to the dynamic one. To encompass more of the dynamic nature of the problem into the static model,

not only the field of displacement is used, but also its convex hull. This strategy allows minor differences between
the models to be taken into consideration. This penalization factor, chosen at the start of the optimization, as well
as the use of the convex hull of the displacement fields were shown to create a fair correspondence between the
models, allowing the problem to be solved in a fraction of the original time, and resulting in valid, optimized
results.