Robust optimization of double pendulum tuned mass damper for vibration control of offshore platforms

Abstract Pendulum tuned mass dampers (PTMDs) have been utilized to suppress the negative effects of vibrations in high-rise structures. In this work, to further improve the performance of a PTMD with a simpler structure, a double pendulum tuned mass damper (DPTMD) is proposed for passive vibration control of structures. A DPTMD includes two PTMDs with different pendulum lengths and masses, and a dashpot is used to connect both pendulum masses. A system including a single-degree-of-freedom (SDOF) structure equipped with a DPTMD under an external force excitation is established. To assess the vibration control capability of this device, the effectiveness and robustness of an optimal DPTMD are computed and compared with those of an optimal PTMD with the same weight. The obtained results show that the DPTMD significantly outperforms the single PTMD across a wider frequency range of excitation force. With the same level of structural vibration reduction, using the DPTMD instead of the PTMD can significantly reduce the absorber’s weight added to the primary structure. The weight reduction achieved by employing the DPTMD rather than the PTMD ranges from 34.8% to 41.2% when aiming for vibration reduction of 60% to 80%. In addition, the DPTMD is less robust than the PTMD in resisting variations in the structural frequency. Nevertheless, if the efficiency is maintained the same as that of the optimal PTMD, the DPTMD offers multiple options for frequency and damping ratio to improve its robustness.