Kadir OZAKGUL, Mehmet Fatih YILMAZ, Barlas Özden ÇAĞLAYAN

Tarihi betonarme kemer bir demiryolu köprüsünün kırılganlık analizi

Bu çalışmada her biri 35m açıklık geçen 7 kemere sahip toplan 285m açıklık geçen, 34m yüksekliğinde ve 15 ‰ eğimli betonarme kemer köprünün kırılganlık analizi gerçekleştirilmiştir. İncelenen köprü 1928 yılında inşa edilmiş ve halen hizmet vermeye devam etmektedir. Köprü Türkiye’nin güneyinde aktif tektonik faaliyetlerin sıklıkla gözlemlendiği bir bölgede yer alması ve ülkenin tarihi demiryolu hattı için büyük öneme sahip olması nedeni ile olasılık bazlı sismik değerlendirmesinin yapılması gereksinimi ortaya çıkmıştır. Bu amaçla, ilk olarak köprünün 3D sonlu elemanlar modeli SAP-2000 programı yardımı ile imalat paftaları kullanılarak oluşturulmuştur. Oluşturulan sonlu elemanlar modeli köprü testinden elde edilen ivme ölçümleri yardımı ile belirlenen mod şekilleri ve frekans değerleri kullanılarak iyileştirilmiştir. Köprüde oluşan sismik taleplerin belirlenmesi için 60 farklı gerçek deprem kaydı kullanılarak zaman tanım alanında analizler gerçekleştirilmiştir. Sismik talep ile sarsıntı şiddeti arasındaki ilişkinin tanımlanabilmesi için olasılık bazlı sismik talep modeli kullanılmıştır. Üç farklı kullanım hızı için köprü açıklığının orta noktasının yatay yer değiştirmeleri hasar parametresi olarak kullanılmıştır. Bunlara bağlı son olarak köprünün kırılganlık eğrileri elde edilmiştir.

Fragility analysis of a historical reinforced concrete arch railway bridge

In this study, fragility analysis of a reinforced concrete arch railway bridge with a total length of 285 m having seven spans of 35 m, a height of 34 m and 15 ‰ slope were performed. The bridge constructed in 1928 still continues to give service. Because the bridge is located in a seismically active region in the southern part of Turkey and on a road, which is critical and important for national railway transportation, it was aimed to perform a probabilistic seismic assessment of the bridge. For this purpose, firstly, 3D finite-element model of the bridge was generated with the software SAP2000 according to the original constructional drawings. Then, the initial FE model was verified using its natural frequencies and mode shapes obtained from in-situ field acceleration measurements. Nonlinear time-history analyses were performed to obtain the seismic demands for 60 different real earthquake records. Probabilistic seismic demand model (PSDM) was derived to determine relations between engineering demand parameter (EDP) and intensity measure (IM). Lateral displacements of the mid-spans were considered as a damage state for three different service velocities. Finally, fragility curves of the bridge were derived.

Keywords:

Reinforced concrete arch bridge, railway bridge fragility analysis, Intensity measure, engineering demand parameter,

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