Wind-Induced Stability of a Cable-Stayed Bridge with Double Main Spans of 1,500 m and a Twin-Box Section: Fid-Bau Portal

Wind-Induced Stability of a Cable-Stayed Bridge with Double Main Spans of 1,500 m and a Twin-Box Section

Hu, Chuanxin / Zhou, Zhiyong / Yan, Kangjian

Both aerostatic torsional divergence and flutter are challenging for the wind-resistant performance of long-span cable-stayed bridges. Aiming at a cable-stayed bridge with double main spans of 1,500 m each and a typical twin-box bridge girder, a combination of wind tunnel tests and nonlinear aerostatic analysis was used to investigate the wind-induced stability of the bridge as well as the effects of central grids with 0% installed on the upper surface of the bridge girder for the wind-induced stability of the bridge. Aerostatic torsional divergence was observed both at initial attack angles of $+ 3 °$ and 0° for the twin-box section and the initial attack angle of 0° for the revised section with central grids with 0%, whereas flutter was observed at the initial attack angle of $+ 3 °$ . Therefore, there are clear competitive relationships between aerostatic torsional divergence and flutter for a revised section with central grids with 0%, depending on the initial attack angle. Furthermore, the addition of central grids with 0% led to deteriorated wind-induced stability, including aerostatic torsional divergence and flutter. Then synchronous evolutionary relationships between structural stiffness and displacements in the instability process are presented. It was found that the downstream cable stress at the center node of the main span decreased prior to the twin-box section when central grids with 0% were added, and the upstream cable stress decreased faster than that of the twin-box section, resulting in the deterioration of aerostatic stability at the initial attack angles of $+ 3 °$ and 0°.