PhD on wind-induced vibrations of long-span bridges in collaboration with NORCOWE
At the University of Stavanger, Etienne Cheynet defended his PhD on the 16th of December. The title was “Wind-induced vibrations of a suspension bridge: a case study in full-scale”, with Professor Jasna Bogunović Jakobsen as the main supervisor and Professor Jonas Thor Snæbjörnsson as the co-supervisor. The study is related to the Coastal Highway Route E39 project where development of new bridge concepts for crossing fjords, which are several kilometers wide and several hundred meters deep, are among the greatest challenges.
Dr. Etienne Cheynet. Photo: Jasna B. Jakobsen
The thesis aims to contribute to an efficient and safe design of such super-long bridges with respect to extreme wind conditions. An extensive set of wind and vibration measurement data, acquired on the Lysefjord Bridge outside of Stavanger, is studied concerning the validity of the current theory for bridge response due to turbulence, as well as methods for identifying the built-in dynamic bridge properties. The thesis shows how the complex surrounding terrain controls the wind conditions at the bridge site, and that the wind flow from the inside of the fjord generates larger bridge vibrations than expected.
A unique part of the work consists of the application of lidars at the Lysefjord bridge site, in collaboration with NORCOWE. The lidar measurement campaign started out by deploying a long-range lidar, with the key involvement of the University of Bergen and Christian Michelsen Research. A follow-up lidar wind measurement campaign was performed in collaboration with Christian Michelsen Research and the Technical University of Denmark who deployed their short-range WindScanner system. The lidar wind data analysis explored and demonstrated how such data can benefit new bridge projects. Long-term wind and vibration recording at the Lysefjord Bridge are performed with the support of and in collaboration with the Norwegian Public Roads Administration.