Vortex‐Induced Vibration Mitigation and Design Optimization of a Long‐Span Bridge Using Multiple Nonlinear Energy Sink Inerters

Vortex‐induced vibration (VIV) in long‐span bridges is a typical form of low‐frequency vibration, which is often challenging to address with tuned mass dampers (TMDs) due to their excessive static displacement and poor robustness. Fortunately, this low‐frequency vibration of bridges can be addressed by the nonlinear energy sink inerter (NESI), owing to its exceptional broadband vibration mitigation capability and the characteristic of low static displacement. In this situation, NESI achieves wider frequency tuning by leveraging nonlinear stiffness and effectively reduces static displacement through the utilization of the inerter’s mass amplification effect. However, in the vibration mitigation of large‐scale structures, the stiffness and inertance of the NESI are often required to be of a larger magnitude due to the excessive modal mass characteristics of the primary structure, which is extremely difficult to achieve in a single NESI (SNESI). Considering this, the present study proposes a strategy employing multiple NESIs (MNESIs) for the mitigation of VIV in long‐span bridges. This strategy guarantees that the stiffness and inertance of each NESI unit remain within feasible limits, while simultaneously ensuring effective elimination of VIV. It is identified that several parameters of the MNESI play a crucial role, and an increase in the modal response difference between the two ends of the inerter is beneficial for enhancing its VIV mitigation capability of the five optimization schemes. Scheme 4, which optimizes the mass ratio, inertance, damping, and stiffness of each NESI unit, is identified as the most effective. It provides VIV mitigation comparable to that of the SNESI while reducing costs by 52%. The MNESI configuration obtained through this optimization strategy has been demonstrated to effectively control VIV in long‐span bridges, while ensuring that the static displacement of each NESI unit remains within acceptable limits under low‐frequency conditions.