ANALYSIS OF PEDESTRIAN CATWALK VIBRATIONS DUE TO HUMAN MOVEMENT

Abstract

The optimal design for pedestrian footbridges often creates light and flexible structures, reducing the overall stiffness and structural mass. As a result, footbridges tend to have low natural frequencies and therefore susceptible to dynamic loading. Dynamic studies evaluate the structure’s response to serviceability limits related to vibrations that are not contemplated in a simplified static analysis. Therefore, common human actions such as walking, running or jumping are important loadings to which a footbridge is subject during its lifespan and must be considered in the design. This paper aims to study the theoretical behaviour of a metallic footbridge built in the city of Itajubá-MG subject to dynamic loads imposed by human movement evaluating its performance in terms of serviceability limits and comfort levels recommended by Brazilian and international design codes. The footbridge was modelled using the computer software SAP2000 and was subject to static, free and forced vibrations loading. The static design was made to compare displacement and load values. The free vibration studies were made to evaluate the natural frequencies and modes of vibration. After applying the pedestrian loading the dynamic response was obtained. The results allowed to verify that the footbridge complies with the serviceability limits imposed by national and international codes due to its high stiffness and lattice shape. The comfort of the users is taken care of in the common situations of use and is satisfactory even in case of vandalism.