Structural response of cable-stayed bridges exposed to strong earthquakes during construction

This paper investigates the earthquake response of the Kömürhan cable-stayed bridge with a single pylon and steel deck, which was exposed to the Elazığ-Sivrice earthquake (Mw = 6.8) on January 24, 2020, while it was under construction. The distance from the epicenter to the bridge is approximately 23 km. 82% of the Kömürhan bridge deck was completed during the Elazığ-Sivrice earthquake in 2020. The spectral accelerations of the Elazığ-Sivrice earthquake are approximately 2.5 times greater than those of the design earthquake (72-year) considered during the construction stage. This paper first presents the characteristics of the Kömürhan cable-stayed bridge and the Elazığ-Sivrice earthquake (Mw = 6.8). Subsequently, a 3D numerical finite model of the Kömürhan cable-stayed bridge under construction is created. Modal and seismic responses of the deck, pylon and cables of the bridge under construction are compared for the load combinations including the design (72-year) and the Elazığ-Sivrice earthquakes. The result shows that under the 2020 Elazığ-Sivrice earthquake, the maximum vertical displacements, axial forces, and bending moments of the deck, as well as the cable forces, are three times greater than the design values (72-year). Nevertheless, despite the significant increase in the structural response, no visual damage was observed on the structural elements. This highlights the conservative design of the Kömürhan cable-stayed bridge.