Coupling coefficient and lateral vibration of slender suspension footbridges

Slender footbridges are known to suffer excessive lateral vibration which is not well understood at present. A suspension footbridge model with reverse profiled cables is proposed to investigate the vibration characteristics of slender shallow suspension footbridges and two types of cable configurations are considered in this paper. It is found that suspension footbridges with shallow cable profiles often have coupled vibration modes which can be described by a “coupling coefficient” defined as the ratio of vertical component to the lateral one. Numerical results show that the coupling coefficient has a significant effect on the lateral dynamic amplification factor (DAF). Small coupling coefficients can induce large DAF in lateral modes.