Nesciobrug

The Nesciobrug, with a length of 780 meters, is one of the longest bicycle bridges in the Netherlands. Named after the Dutch writer Nescio, this bridge is located in Amsterdam, spanning the Amsterdam-Rijnkanaal. Its elegant and slim design makes the bridge very flexible. To prevent excessive swaying, Flow Engineering designed a damper system for the first and second resonance frequencies. To maintain the bridge’s elegant design, the damper system is integrated into the structure.

The bridge is equipped with three Tuned Mass Dampers (TMDs) supplied by Flow Engineering. The first TMD, weighing 10,000 kg, is placed in the middle of the span and is responsible for damping the first mode of vibration, achieving a damping ratio of 5% compared to critical damping. The remaining two TMDs, each weighing 1,500 kg, are located at 1/4 and 3/4 of the span and are designed to damp the second mode of vibration, achieving a damping ratio of 7.5% compared to critical damping.

The dampers are placed to mitigate potentially dangerous vibrations caused by pedestrians, primarily in the lateral direction of walking. Without these dampers, a phenomenon known as the lock-in effect could occur when the bridge is walked on by several or many pedestrians. One of the more famous examples of this phenomenon is the Millennium Bridge in London, UK.