Eartquarke performance evaluation of an existing railway bridge by nonlinear metods

The Turkish Bridge Earthquake Code (TKDY) was published in the Official Gazette on October 6, 2020, and came into force on October 6, 2021. This regulation has been implemented for the first time as a standalone code in Turkey and mandates performance-based design for bridges. Prior to this date, bridges were designed and constructed in accordance with the recommendations of either the American Association of State Highway and Transportation Officials (AASHTO) or the International Union of Railways (UIC). The devastating earthquakes that occurred in Türkiye on February 6, 2023, attracted attention with their destructive impact and have been reported in many studies as being of a rarely observed magnitude globally. These earthquakes revealed the critical importance of rapid emergency response across a large region inhabited by approximately 14 million people. The necessity for aid teams to reach the disaster area swiftly was clearly demonstrated. In this context, ensuring that transportation structures serving the public can either continue to function without damage or be repaired quickly with minimal intervention is of great significance. Within the scope of this thesis, the relevant sections of the 2020 TKDY code have been examined in detail. The study evaluates the seismic performance of a railway bridge located between Banaz and Eşme on the Ankara-İzmir High-Speed Train (HST) line using time-history analysis, which is required as the second-stage method for bridges classified as Importance Class 1 and Seismic Design Class 1 according to the code. The bridge consists of 10 spans and 9 piers. The study includes the selection of earthquake records from the Pacific Earthquake Engineering Research Center (PEER) Ground Motion Database. These records were selected considering factors such as earthquake magnitude consistent with the design-level ground motion, fault distances, source mechanisms, and local site conditions. As the viaduct analysis requires three-dimensional modeling, seven earthquake records were selected as per the code. These records were applied to the model in a cross-combination manner using the SAP2000 software, resulting in a total of 14 analyses. Consequently, the seismic performance level of the viaduct was evaluated under various earthquake scenarios.