The stiffness of a long-span cable-stayed bridge under construction may be much lower than that observed in service, making it more susceptible to wind effects, especially for a bridge designed using high piers crossing a deep canyon. To study the buffeting characteristics of such cable-stayed bridges under construction, a long-span cable-stayed bridge (the main span is 575 m) is taken as the engineering background. In this study, the buffeting responses and vibration countermeasures at three different construction states were systematically studied using time-domain analysis. It was found that the buffeting response enlarges with an increase in the wind attack angle. The RMS values of the vertical buffeting of the bridge deck end are relatively greater at the maximum double cantilever construction state and maximum single cantilever state. At maximum double cantilever construction state, the traditional wind-resistant cable connecting the bridge deck end to the bridge pile cap significantly reduces the vertical buffeting response, while the suppression effect on lateral and torsional buffeting is limited. When the bridge deck nears completion, wind-resistant cables installed at both cantilever ending in the ‘soft connection’ method would effectively suppress the vertical, lateral, and torsional buffeting. The suppression effect of cross-arranged wind-resistant cables is superior to that of the parallel arrangement. It is recommended that a reasonable wind-resistant cable layout scheme according to different construction conditions is selected.

A significant aerodynamic interference effect exists between parallel bridges. In this study, a proposed long-span cable-stayed bridge, near which is an existing truss-arch bridge, was considered as the background. The wind characteristics at the proposed bridge site and the wind-induced responses of the bridge deck were investigated with and without the influence of an upstream bridge. The results showed that under aerodynamic interference of the upstream bridge, the downstream bridge site exhibited a noticeable change in the mean wind speed profile within the height range of the main girder and arch. The turbulence intensities significantly increased, especially for u and w components. The integral scales decreased remarkably, and the wind speed spectra redistributed toward higher frequencies. For the wind-induced responses, the mean displacements of the downstream bridge all decreased; in contrast, the buffeting and peak displacements all increased in both the maximum single cantilever state and the completed state, while the variation in buffeting response was much more significant and dominated the peak response. Moreover, under the interference of the upstream bridge, the buffeting displacement spectra redistributed toward high frequencies. This research acts as an effective tool for achieving secure bridge design and finding a better balance between design constraints.