Knowing the real dynamic properties of a structure, natural frequencies and vibration modes is essential to ensure comfort and safety for users, as well as predictability for maintenance of public equipment. With this objective in mind, two pedestrian footbridges on the São Paulo subway were monitored by IEME Brasil last March, which used Vibrodina, a mechanical device that makes the structure vibrate at a specific frequency range, in the dynamic forced vibration test.

“The precise determination of the structure’s natural frequency is extremely important for validating theoretical models and ensuring that it does not coincide with the excitation frequencies generated by pedestrian traffic. Avoiding resonance is essential to ensure user comfort and the structural integrity of the footbridge,” explains engineer Marco Juliani, director of IEME.

The footbridges are located at the Santo Amaro station of the São Paulo subway, which is shared by subway lines 5-Lilás (ViaMobilidade) and 9-Esmeralda, of CPTM. They are 111m long and 7.4m wide and are formed by a metal lattice structure with tubular profiles and a steel deck slab. The central span, which crosses the Pinheiros River, is approximately 80m long. The work is the responsibility of EGTC Infra.

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