OPTIMAL-CONTROL OF ABOVEGROUND PIPELINES UNDER DYNAMIC EXCITATION

The aim of the present paper is to contribute to the research on the a pplication of computer-controlled devices controlling the dynamic resp onse of aboveground pipelines. To this end, the optimal control proble m of above-ground pipelines loosely resting on steel saddles and under going strong ground shaking is studied. By applying an appropriate spa ce discretization scheme to the continuous system and assuming that th e unilateral contact between the pipe vessel and the saddle is frictio nless, the dynamic behaviour of the pipeline subject to control is inv estigated. Then, by applying an appropriate time discretization scheme , the state relation of the problem arising within each time step is f ormulated as a quadratic optimization problem, thus leading to an equi valent transformation of the initial dynamic problem into a sequence o f quasi-static discrete optimal control problems. For the numerical tr eatment of the formulated problems, a solution scheme is proposed; an efficient quadratic optimization algorithm exhibiting the great advant age to transform the initial quadratic programming problem into a sequ ence of linear problems is applied to the numerical treatment of the s tate relation of each subproblem. The efficiency and the applicability of the proposed method are illustrated by means of a numerical exampl e.