Creative Design and Scientific Investigation

This paper describes the creative design of an aesthetically striking footbridge, and the state-of-the-art investigations involved in the evolution of its design. Details are presented on many aspects of the engineering design, including bridge aerodynamics and wind tunnel testing, second order slenderness, pedestrian induced excitations, and seismic actions. Static, dynamic, and aerodynamic stability and performance are discussed. To integrate design with construction, an envisaged construction method and sequence were developed, and robustly examined and improved as an essential part of the design development. On aerodynamic investigations, stability and performance are discussed. Section model wind tunnel testing and aeroelastic full bridge model testing are described. On seismic analyses, the performance of the S-curve footbridge under seismic events is discussed. The use of an elastic seismic response spectrum analysis and a time-history non-linear analysis is described. On second order effects, the paper describes the potential of second order effects, arising from the dimensions of the footbridge members being relatively small compared to the span involved, and resulting in the member deflections increasing the bending effects considerably. Geometric nonlinearity and susceptibility to buckling is discussed. On pedestrian induced excitation, a general discussion is given on the phenomenon of pedestrian induced excitation in footbridges. Then a detailed description is given on the use of state-of-the-art techniques for eigen-analysis and time-history analysis of pulsating loads, as part of our efforts to explore vibration mitigation.