Congreso celebrado en la Escuela de Arquitectura de la Universidad de Sevilla desde el 24 hasta el 26 de junio de 2015.In this paper, a case study about a lively footbridge is developed; the vibration levels caused by the
pedestrian action are controlled by the change of the modal parameters of the structure due to the
pedestrian-structure interaction. A detailed finite element model of the structure has been updated
from an operational modal analysis. The updated model has been used to obtain the numerical
acceleration at the mid-span of the footbridge under different pedestrian flows. A relation between
the maximum acceleration and the pedestrian density on the deck has been obtained numerically,
pointing out an improvement in the comfort level of the structure when the number of pedestrians
increases. This result validates a design rule for cable-stayed footbridges in order to avoid vibratory
problems, since the first vertical natural frequency of the structure remains below the range that
characterizes the pedestrian walking action
