Gilvan Lunz Debona

Vibration Analysis and Human Comfort Evaluation of Steel-Concrete Composite Footbridges Based on the Modelling of the PedestrianStructure Dynamic Interaction Effect

This work aims the development of an analysis methodology to investigate the dynamic behaviour of steelconcrete composite footbridges. The composite footbridge dynamic response is analysed based on two different strategies. Firstly, the traditional simulation of human walking, without consideration of the pedestrianfootbridge dynamic interaction effect is considered. On the other hand, the effect of the dynamics of the pedestrians while crossing footbridges in crowd situations is analysed and the pedestrian-footbridge dynamic interaction, based on the use of biodynamic models is investigated using a second strategy. The investigated structural system corresponds to an existing pedestrian footbridge built on Ayrton Senna Av. in the city of Rio de Janeiro/RJ, Brazil, with a central span of 68.6m. The footbridge dynamic response was obtained and compared to the limiting values proposed by several authors and design standards. The results indicate that the biodynamic loading models lead to peak accelerations values lower than those produced by the traditional methods. These results provided evidence that the pedestrian-structure dynamic interaction effect should be considered when composite footbridges are subjected to flow of pedestrians.

Analysis of the Dynamic Behaviour of Steel-Concrete Composite Footbridges Considering the Soil-Structure Interaction

The main objective of this investigation is to present the finite element modelling of the dynamic behaviour of a steel-concrete composite footbridge, when subjected to human walking vibrations. The investigated structural system was based on a tubular steel-concrete composite footbridge, spanning 82.5 m. The structural model consists of tubular steel sections and a concrete slab. This investigation is carried out based on correlations between the experimental results related to the footbridge dynamic response and those obtained with finite element modelling. The soil-structure interaction effect was considered in the dynamic analysis based on the use of Winkler’s theory. The finite element model enabled a complete dynamic evaluation of the tubular footbridge in terms of human comfort and its associated vibration serviceability limit states. The peak accelerations found in this analysis indicated that the investigated footbridge presented problems related with human comfort and it was detected that the structural system can reach vibration levels that compromise the footbridge user’s comfort.

Finite Element Modelling of the Dynamic Behaviour of Tubular Footbridges

Tubular hollow sections are increasingly used in off-shore structures, highway bridges, pedestrian foot-bridges, large-span roofs and multi-storey buildings due to their excellent properties and the associated advances in fabrication technology. The intensive use of tubular structural elements in Brazil, such as the example depicted in Figure 1, mainly due to its associated aesthetical and structural advantages, led designers to be focused on their technologic and design issues.