Coupled flutter mechanism of flexible suspended pedestrian bridges

Flexible suspended pedestrian bridge (FSPB) is a distinctive structure with a taut catenary shape in which separated deck modules are supported by suspension cables. FSPBs are characterized by high flexibility and large deformation arcs due to their low structural stiffness and damping, exhibiting significant aeroelastic interactions between modes. This study focused on flutter, an aeroelastic instability issue, in FSPBs. Wind tunnel tests and numerical analyses were conducted on two deck designs: open grating (OG), which minimizes air resistance, and solid deck (SD), which fully blocks the deck grating. Results showed that SD exhibited relatively vulnerable aeroelastic behavior, while the OG demonstrated greater stability against flutter. Numerical analysis explored the mode coupling of the entire bridge, examining the influence of lateral modes and degrees of freedom (DOF) on the onset of coupled flutter in the SD. The applicability of a two-dimensional (2-D) wind tunnel test setup was also examined. Additionally, the study identified the developing mechanism of torsional-vertical coupled flutter and key parameters influencing critical modes using 2-D wind tunnel tests and time-domain flutter analysis.