Design Method for the Dynamic Scale Model of Pedestrian Footbridge

Abstract

This paper studies the design method for the dynamic scale model of a pedestrian footbridge. A typical pedestrian footbridge was taken as the prototype and the actual structural properties and dynamic mechanics theoretical analysis based on the dynamic similarity theory for the scaled test model was used so as to deduce structurally similar ratio parameters in the scale model. Then, combined with the practical feasibility, the model is designed and produced. Compared with the dynamic field test, the finite element method analysis shows that the dynamic properties of the scaled model are very similar to the actual prototype. This designed scale model can satisfy the study on the dynamic response of pedestrian footbridges under pedestrian loads or ambient excitation. This design method for the dynamic scale model of pedestrian footbridges supplies a new approach for the study on vibration serviceability of pedestrian footbridges. In current civil engineering construction, more economic and aesthetic factors are considered in the design of all types of buildings and bridges. With the development of calculation methods in the designs and with the widespread use of lightweight and high strength structural materials, these structures are becoming larger, lighter weight, more flexible and lower damping. Although the static performance of these structures can satisfy classical structural requirements, such as bearing capacity and deformation, it brings about another problem. Its dynamic performance of serviceability limit state, especially excessive man-induced vibration of the pedestrian bridge by the overcrowded pedestrian load, will cause the people to feel uncomfortable, or even nervous and panic, while they are walking along the bridges. Man-induced vibration of footbridge structures has been researched for a period of time both at home and abroad, but most of the research is in the form of theoretical studies. For example, Jacobs, Skorecki and Charnley have researched the pedestrian’s vertical load under normal walking and other forms (Jacobs 1972). J.E. Wheeler has proposed that human-induced vibration of footbridges can be treated as forced vibration (Wheeler, 1982). The pedestrian’s walk load relates to its movement