Most modern footbridges are slender and weight structures which are sensitive to pedestrian induced vibration due to less mass and less stiffness. Pedestrian feel uncomfortable or cannot continue to walk when the step frequencies of pedestrians and natural frequency of the structure coincide or have close range of frequencies in the first 2 modes. Opening ceremony of Millennium Bridge sent a clear signal that only static design is not enough for certain structures. There are some guidelines on footbridge vibration design, they set critical frequencies range in both vertical and horizontal with simplified SDOF (Single Degree of Freedom) formulas therefore, this thesis will examine whether a designer could be satisfied with these simplified formulas by comparing with FEM (Finite Element Method) results. In conclusion, the problem which thesis will solve is only confined to this type of bridges i.e. simply supported; other types should be another case to be studied.

Master's thesis in Mechanical engineering

Statens vegvesen