Dynamic analysis of footbridges excited by pedestrians
In this work, we will discuss the dynamic analysis of two footbridges to be installed next to the Santo Amaro subway station, the Passarela Norte and Passarela Sul, both with 111 meters of span. In particular, the Service State Limit of excessive vibrations excited by pedestrian movement in the vertical and lateral directions will be studied.
In the first part of this work, the concepts necessary for its development will be presented. Later the model used will be presented as well as its results, solutions and conclusion.
The structure was modeled using STRAP structural analysis software. The steel profiles used were provided by the authors of the architectural and structural designs, being typical of these structures. Available footbridges literature provides a deterministic model for dynamic loading due to people's walking.
When the natural frequency of the structure is close to people's walking it can lead to pedestrian discomfort and even a feeling of insecurity. In addition, it can shorten the frame life due to material fatigue and further maintenance may be required.
Processing suggests the presence of accelerations above the desired or anticipated by several international standards on the subject. To mitigate them, passive vibration absorber (TMD's) control is proposed for vertical and lateral vibrations.