System identification of Bogazici suspension bridge during hanger replacement

Abstract

Bogazici suspension bridge is one of the long-span bridges crossing over the Bogazici strait. It was opened to traffic in 1973 and from that day on it has been one of the most important links in the traffic network of Istanbul. It has a main span of 1074m and the original configuration of the suspension hangers was inverted - V shape. In 2015, the suspension cables were replaced and the orientation of the cables was changed to vertical. During this campaign, vibration measurements were recorded on the tower, deck and the suspension cables of the bridge. Measurements were taken at different stages of this campaign to have an understanding of the effects of cable replacement on the overall dynamic behaviour. Additionally, measurements were recorded for at least several days to several weeks to observe operational variations on the modal frequencies of vibration. Results show that frequencies of the deck motion dominant modes decreased by 6 to 12% and there were almost no change in the tower motion dominant modal frequencies due to replacement of the hangers.