Monitoring and Assessment of Bridge Cable Stays Consisting of Bundles of Fully Locked Coil Ropes

Abstract

The paper describes the health monitoring of the cables of the largest cable-stayed bridge in Slovakia. The bridge spans the Danube River and is located in Bratislava. It was opened for traffic in 1972. The bridge is known for the restaurant at the top of its inclined pylon. The cables consist of bundles of fully locked coil ropes.The vibration method was used to assess the forces and damping of the cables. The results were compared with the topographical measurement method. The distribution of the total force in the stays among the individual fully locked coil ropes was also investigated by the vibration method. The measurement was performed in the anchor chambers in the bridge beam where the bundles of ropes spread out. Due to the short lengths of the ropes, the influence of their bending stiffness had to be considered. A non-linear fitting procedure with minimising the sum of squares was used.A set of up to nine accelerometers was used to measure the vibration of individual ropes. A study on the number of necessary considered mode shapes was also performed. Ambient vibrations were used for the operational modal analysis and impact loads coming from a hammer were used for excitation as well.