LAUSR

Abstract Using a submerged pipeline section modeling the touchdown zone (TDZ) of a steel catenary riser (SCR), a sequence of contrast experiments were carried out to investigate the influences of seabed stiffness and water damping. Acceleration signals and bending strains at discrete positions along the TDZ pipe model were recorded during the testing, and by dealing with response-only data using the frequency domain decomposition method (FDDM) the results characterizing TDZ dynamic behaviors were acquired. These results indicate that under the excitation from the seabed model the complex modal responses appear with much higher frequencies than the end-loading one, similar to the dynamic response of a SCR TDZ, whose practical vibration frequencies are much higher than the heave motion of a hull. Identifications of complex modal parameters have proven to be effective using experimental response data, and this identification process can be applied in SCR TDZ monitoring to investigate seabed stiffness influences and water damping effects.