Marine Riser Vibration Response Determined by Modal Analysis

Marine riser response calculations are usually based on finite element or finite difference methods. This paper outlines the modal analysis method as an alternate approach for calculating marine riser time-dependent stresses. An example problem shows that five natural vibration modes give acceptable convergence and engineering accuracy. Dynamic response calculations are, therefore, greatly simplified as only a limited number of eigenvalues and eigenfunctions are needed. In addition, the time-dependent part of the solution can be determined from elementary single-degree-of-freedom-type equations.