A novel casing-pipe type TMD for seismic control of free-spanning submarine pipelines: Shaking table tests and numerical simulations

Abstract

Submarine pipelines are vital lifeline engineering structures for transporting offshore oil and gas resources, which may experience adverse vibrations against structural safe operation when encountering strong offshore earthquakes. This paper proposes an innovative casing-pipe type tuned mass damper (CPTMD) for the seismic control of free-spanning submarine pipelines (FSSPs). The design concept and control mechanism of the CPTMD are firstly presented. Both shaking table tests and numerical simulations are performed to examine the effectiveness of using the CPTMD to reduce seismic-induced vibration of FSSPs, through comparing structural seismic responses with and without damper device. In the experimental and numerical studies, the effect of seawater around submarine pipelines is simplified using the added hydrodynamic mass method. The experimental and numerical results consistently demonstrate that the proposed CPTMD has a good capacity for suppressing seismic-induced vibration of FSSPs. Moreover, the impacts of stiffness, damping coefficient, mass ratio and casing-pipe length on the seismic control effectiveness of the CPTMD device are investigated and discussed comprehensively, and the optimal values of these design parameters are determined. As a result, the proposed CPTMD could be an effective and simple solution for the vibration control of FSSPs induced by offshore seismic motions.