Analysis of vertical vibrations induced by vehicular traffic on bridge decks made of UHSC (Ultra high strength concrete) for the purpose of comfort for pedestrian traffic. Comparison between numerical models and experimentation on real bridges.

The Municipality of Rotterdam's engineering office is increasingly turning to the use of intelligent products; not just fibre-reinforced polymers, but fresh techniques such as Ultra High Strength Concrete (UHSC). It is now conceivable with the use of these innovative materials to reach higher slenderness ratios. Using these innovative materials, it is now conceivable to achieve greater slender ratios. The resulting weight decrease of a new bridge means that it is more susceptible to vibrations, which can cause pedestrians significant discomfort when using it. The pedestrians’ understanding of such vibrations is complex and not readily measured, but the ranges of accelerations and displacements corresponding to different levels of suitability were investigated. The design of the bridges is currently carried out in accordance with the modern Eurocode regulations and guidelines, which recommend simple load models to simulate the loading of the vehicles and introduce additional acceleration restrictions to certify that the comfort of the pedestrians is met. However, the recommended acceleration limits are excessively small, with no additional description of how they were chosen. It was evident from the literature research that the perception of pedestrian vibrations is a complicated concept, not possible to measure because it varies on countless variables, some of which are the position of the human body, pedestrian age and gender, bridge use, bridge dynamic characteristics. Factors such as structural damping also have an important impact on the structure's reaction and should be examined more thoroughly. Due to the extreme complexity of expressing vibration consciousness and pedestrian discomfort, it was deemed too conservative to cover all the components that influence the comfort threshold in a single acceleration value. It was therefore decided to explore the extent of accelerations and displacements to which active and inactive pedestrians resemble distinct levels of comfort. Experiments were carried out on a bridge for this purpose, where the accelerations and displacements caused by vehicle-induced vibrations were noted and the pedestrians evaluated the comfort level they felt for the various experiments. Subsequently, in a Finite Element Analysis program these studies were simulated and the theoretical and realistic car load models were applied. The structure response obtained from the model was linked to the structure's real action. In addition, an assessment was made between the responses and the classifications of comfort resulting from the application of the codes.