DYNAMIC BEHAVIOR OF CABLE-STAYED BRIDGE IN THE WAKE OF AN ARCH BRIDGE

The study of the dynamic behaviour of a cable-stayed bridge located in the close wake of an arch bridge is performed in two ways: a wind tunnel study on an aeroelastic model a theorical computation after preliminary measurements in the wind tunnel of the detailed characteristics of the turbulence in the wake. These two approaches show a very pronounced dynamic behaviour of the cable-stayed bridge caused by vortex shedding on the top of the arches of the existing bridge. Geometrical modifications of the arches of the bridge allow to reduce wind-sollicitations on the cable-stayed bridge. A comparison between these two methods leads to estimate the aerodynamics admittances in this particular high turbulence case. Aerodynamic damping has been also measured on the aeroelastic model and is compared to the quasi-steady assumption.