Modal and dynamic analysis of a footbridge in service

Civil engineering constructions like pedestrian footbridges are structures increasingly slender, ambitious and complex in which the dynamic effects caused by the loads to which they are subjected (pedestrians) may induce service problems and / or significant or repetitive amplifications of the efforts and deformations. This fact together with the current social demands related to the perception and comfort raise the need to integrate the analysis and computer-aided design in the evaluation of the vibrations generated by the loads this type of structures supports. In the specific case of finite element commercial programs, their use has not proliferated as much as in other engineering fields due to the existence of simplified methodologies in numerous national and international guidelines and regulations and the difficulty of making realistic models in the case of complex structures. However, the knowledge generated by the analysis of this type of numerical models would be especially useful in the earlier phases of the design of similar structures, so much initial as of the necessary modifications to solve existing dynamic problems, since it is in these stages when the best solution could be applied from both a technical and an economic point of view. This article describes the process of generation and updating of the mechanical finite element model (FEM) of a footbridge in service and the simulation of two types of load: an excitation generated by a shaker and a pedestrian load, contrasting the results generated by the numerical model with those obtained experimentally.