Dynamic analysis of marine risers considering parametric excitation

Abstract

This paper presents a dynamic analysis of marine risers subjected to wave forces. Long cylinderical marine structures such as riser are subjected to several kinds of loadings. The important forces are those due to wave, current and motion of the floating structure to which the risers are attached. The governing partial differential equation for the lateral motion of the riser is transformed into the descrete equation of motion using finite element method. The nonlinear equation caused by the wave drag forces is approximately solved by using undamped free vibration modes. The study focuses on the effect of the parametric excitation caused by the vertical motion of the floating structure and the P-Delta effect induced by the large lateral displacement of the riser. Generally the parametric excitation and P-Delta effect increse maximum bottom angle and induce the rapid increment of bending moment.