Random Vibration of Steel Catenary Riser Conveying Fluid Under Wave Excitation

Abstract

This paper presents a frequency domain approach for the calculation of the random response of fluid-conveying steel catenary risers under random wave force. The partial differential equations of motion of the steel catenary riser under a combination of internal flow and random wave excitation are established based on a series of earlier publications. The mass matrix, stiffness matrix, damping matrix and wave loading for steel catenary riser are derived in frequency domain by using Hamilton's principle. Analysis of free vibrations is then carried out to investigate the effect of flow velocity on natural frequency. By further introducing the pseudo-excitation method, the dynamic analysis of the steel catenary riser subject to wave excitation is performed in frequency domain to see how the flow velocity affects the bending moment response of the steel catenary riser. The parametric studies on the example steel catenary riser show that flow velocity may decrease the natural frequencies and increase the dynamic response of the steel catenary riser. Moreover, the dynamic stability of fluid-conveying steel catenary risers is investigated and the critical fluid velocity is identified.