Wind-Induced Buffeting Vertical Deformation Control Using Ground-Anchored Hangers for a Main-Cable-Looped Suspension Bridge

As a relatively flexible structural system, main-cable-looped suspension bridges are susceptible to wind-induced buffeting, which causes significant vertical structural deformation. Therefore, it is essential to study the vertical deformation response characteristics of main-cable-looped suspension bridges under wind-induced buffeting, as well as corresponding control measures. In this study, a three-dimensional finite-element model was established for China’s first main-cable-looped suspension bridge. A segmental model of the steel truss girder was fabricated, and wind tunnel tests were conducted at different wind attack angles to determine the aerodynamic coefficients of the steel truss girder. Using the wind field characteristics at the bridge site, the harmonic synthesis method was applied to simulate the three-dimensional fluctuating wind acting on the steel truss girder, which was validated via power spectral density and cross-correlation function analyses. A linear time-domain buffeting analysis accounting for structural nonlinearities was performed to investigate the response of the suspension bridge. A parametric study was also carried out to examine the wind-induced buffeting vertical deformation response of the suspension bridge and the control effectiveness of ground-anchored hangers. Under wind-induced buffeting, the maximum vertical deformation of the main-cable-looped suspension bridge increases nonlinearly with rising average wind speed. Notably, the growth rate of the maximum vertical deformation for both the steel truss girder and the U-shaped main cable changes significantly when the average wind speed reaches 19.5 m/s. Within the range of ±10°, the maximum vertical deformation of the bridge first increases and then decreases as the wind attack angle increases. The maximum upward deformation of both the midspan steel truss girder and the U-shaped main cable peaks at a wind attack angle of −4°, while the maximum downward deformation peaks at a wind attack angle of 0°. Ground-anchored hangers effectively reduce the upward vertical deformation of the main-cable-looped suspension bridge under wind-induced buffeting. The optimal longitudinal position for the ground-anchored hangers is 20–22.5 m from the rotating saddle. The maximum upward vertical deformation of the steel truss girder and the looped main cable can be reduced by approximately 6.2% and 11.1%, respectively.