Structural health monitoring systems of long-span bridges in Turkey and lessons learned from experienced extreme events

Long-span bridges constitute one of the most critical lifelines in countries where they are constructed since they shorten transportation by providing passage through large waterways, such as rivers, channels, dams, and the sea. Owing to its geographical location, Turkey is a transit country between Asia and Europe. As long-span bridges are subject to heavy traffic and seismic hazards in Turkey, monitoring their structural health and performing their maintenance in a timely and cost-effective manner is essential. These bridges pose maintenance challenges due to their sizes. Because of their high towers and hard-to-access cables in general, the most reliable method of monitoring the structural condition of such bridges under service is to build structural health monitoring (SHM) systems. This paper reports on the results of a study in which the SHM systems of long-span bridges in Turkey, which are among the largest bridges across the world, are described. The characteristics of these systems utilized are explained in detail. In addition, SHM data acquired on the Fatih Sultan Mehmet Bridge during a recent offshore event on 26th September 2019, the Silivri Earthquake (M-w 5.8), are analyzed. The findings are validated using experimental research results presented in the literature, and the comparison was indicated good agreement to identify the bridge's dynamic characteristics. Finally, problems encountered in SHM systems because of extreme loads are explained, and recommendations are provided for future applications.