A contribution to the sensitivity analysis of the sea-bed-structure interaction problem for underwater pipelines

Abstract The sensitivity analysis problem for a pipeline freely resting on a frictionless sea-bed profile is considered. First, the sensitivity problem is formulated for the discrete structure having taken into account the unilateral contact phenomenon, i.e. the possibility, for certain regions of the pipeline to be in contact with the underlying sea-bed profile, whereas the rest to lie above it. The sensitivity problem is thus formulated as a quadratic programming problem with inequality constraints which can be solved by means of the suitable application of the Theil-van de Panne method that transforms the initial sensitivity problem into a sequence of linear problems. The solution of the latter problem leads to the solution of the sensitivity analysis problem under consideration. The applicability of the proposed method is illustrated by means of two numerical examples.