A Passive Self‐Tuning String‐Mass Absorber and Its Application in Vortex‐Induced Vibration Control: Theory and Numerical Analysis

This study proposes a nongrounded passive self‐tuning string‐mass absorber, consisting of a mass block, a tensioned string, movable hinge fulcrums, an inertial amplification component, and a purely mechanical self‐tuning mechanism. The absorber tunes its frequency by varying the effective length of the tensioned string through automatic adjustment of the hinge fulcrum positions. Specifically, the hinge fulcrums remain fixed when the response of the primary structure is below a prescribed threshold; otherwise, the self‐tuning mechanism is activated and continuously adjusts the fulcrum positions until the structural response is reduced below the threshold. The self‐tuning mechanism integrates sensing, actuation, and transmission functions, and is powered entirely by the vibration energy of the primary structure, eliminating the need for any external power supply. To demonstrate its applicability to long‐span bridges, two case studies involving detuning and multimodal vortex‐induced vibration conditions are conducted. Numerical results indicate that the absorber exhibits robust self‐tuning capability and maintains effective vibration mitigation performance under complex operating conditions.