Monitored seismic performance assessment of cable‑stayed bridges during the 2023 Kahramanmaraş earthquakes (M7.7 and M7.6)

The devastating earthquake sequence struck Kahramanmaraş, Turkey, in February 2023, resulting in significant casualties and structural damage to buildings and engineering structures. There is limited research on the real earthquake performance of cable-stayed bridges exposed to severe earthquakes in the literature. This study aims to investigate the monitored seismic performance of cable-stayed bridges in the region during the February 6, 2023, Kahramanmaraş earthquakes (M7.7 and M7.6). Firstly, an overview of the ground motion characteristics of the destructive earthquakes and the damage in the affected region is presented. Subsequently, the monitored seismic performances of the Nissibi, Ağın, and Kömürhan cable-stayed bridges are separately evaluated, considering on-site observations and the strong ground motion data recorded at the accelerometer stations closest to the bridges. Furthermore, a comprehensive analysis of the real monitored structural responses of the Kömürhan cable-stayed bridge during the M7.6 earthquake is conducted. This analysis is based on data collected by the bridge’s fixed monitoring system, including accelerations, strains, and cable strand forces. Additionally, the dynamic characteristics of the Kömürhan Bridge are extracted and evaluated by signal processing of the monitoring data, comparing these characteristics with the bridge design specifications. The results of this investigation offer valuable insights into the actual seismic behavior of cable-stayed bridges situated in the proximity of fault lines during strong earthquakes.