Session: 04-04-03 Rigid Pipelines III

Submission Number: 176129

Assessment to the Free Vibration Characteristics of Subsea Jumpers 

 

The free vibration of submerged line structures is crucial in assessing the structure integrity under dynamic loads, such as earthquakes, underwater explosions, vortex-induced vibration loads, etc. Typically, when conducting modal analysis of submerged structures, engineers consider the surrounding water by using constant added mass factors. However, this method has proven to be inaccurate for complex structures based on authors’ earlier work, particularly those with bends and multi-plane topologies such as subsea jumpers or spools. It is shown that a more sophisticated approach is needed to accurately analyze these types of structures with correct consideration of surrounding water effects. We have utilized the coupled structural approach (CASA) in Abaqus, where the surrounding water has been represented by acoustic elements and the coupling between structure and acoustic elements is achieved via auto-contact algorithms. We compared CASA with traditional methods, in which constant added mass was used together with pure beam elements, beam and elbow elements, or shell elements. It is shown that the traditional methods have their limitations in simulating the multiplanar line structures. The advantages and disadvantages of using the CASA and traditional methods have been summarized. Accordingly, recommendations that might be useful for the structural analysis of such structures have been made.

Presenting Author: Zhenhui Liu Aker Solutions

Presenting Author Biography: phd on marine structures since 2011

Authors:

Oskar Ullestad DOF Group
Zhenhui Liu Aker Solutions