Vibration Reduction Using Tuned Mass Dampers in Composite Steel Box Girder Footbridge with Self-Anchored Suspension

Owing to the increasing span of pedestrian bridges and the use of new lightweight and high-strength materials, the natural frequency of pedestrian bridges has been reduced significantly. A pedestrian bridge experiences a wide range of vibrations while being walked on by large crowds. This type of vibration affects the comfort of people walking on the footbridge and also the safety of the footbridge. This paper proposes a dynamic design method that is suitable for long-span composite footbridges. The footbridge considered in this study comprises a composite steel box girder with self-anchored suspensions and has a main span of 70.5[Formula: see text]m. The dynamic characteristics of the long-span footbridge were analyzed using the finite element model, and the first 10 frequencies and mode shapes were obtained. Based on the global analysis of comfort standards, the comfort index for a practical evaluation was proposed, along with the walking excitation load. Meanwhile, a tuned mass damper (TMD) was adopted for the vibration reduction of the long-span footbridge constructed using a composite box girder with self-anchored suspensions in order to determine its applicability. Furthermore, the TMD layout was optimized using a GA. The results demonstrated that the proposed method can provide a theoretical basis and reference for the dynamic design of long-span composite pedestrian bridges.