Pedestrian loads and dynamic performances of lively footbridges: an overview on measurement techniques and codes of practice

Modern pedestrian bridges are very often lively structures, due to the increasing strength of materials and the request for greater slenderness. Their natural frequencies are usually very close to the characteristic frequencies of the pedestrian dynamic loading, so that they are extremely prone to vibration. Human-induced vibrations reduce the footbridge serviceability and often imply high costs for the assessment of the dynamic behavior of the bridge after the construction. Therefore, it is really important to define comfort criteria, suitable and predictive load models and practical design rules, to avoid the occurrence of uncomfortable oscillations. The scope of this paper is to provide an overview of the state of the art concerning human induced vibrations on footbridges, through a description of the main features of the pedestrian loading, a review of the different types of experimental tests, of comfort criteria and load models provided by codes and guidelines.