Seismic Assessment Of Multi-Span Steel Railway Bridge In TurkeyBase On The Nonlinear Time History Analyses

It has been seen that bridges are vulnerable to earthquakes by the research studies after important earthquakes like the San Fernando earthquake (1971 USA), the Northridge earthquake (1994 USA), Great Hanshin earthquake (1995 Japan), and Chi-Chi earthquake (1999 Taiwan). These studies show that to do the seismic risk assessments for bridges, fragility curves are useful tools. There are the most used two ways to generate the fragility curves; empirically or analytically. If the damage reports from past earthquakes are available then empirical fragility curves may be developed but otherwise seismic response analysis of structures may be used to develop analytical fragility curves. In Turkey, earthquake damage data are very limited so to develop the fragility curves for the Alasehir bridge, the analytical method is used in this study. The bridge that is studied on is lying on the Manisa-Afyon railway line that is very important for both transportation and freightage. As the most of the country land covers the seismically active zones it is a necessity to find out the vulnerability of the Alasehir bridge. The Alasehir bridge is consists of six 30 m length truss system span with a total span length of 189.43 m supported by 2 abutments and 5 truss piers with height of 12.5 m, 19 m, 26 m, 33 m and 40 m. Sap2000 is used for computer model of the Alasehir bridge and the model is refined by using field measurements. Then selected 60 different real earthquake data are used for the analysis by using the refined model. Both material nonlinearity and Δ-δ are considered during the analysis. With this study, seismic behavior of Alasehir steel railway bridge is determined. Truss piers reaction and displacements are used to determine the seismic performance of the Alasehir bridge. Different IMs are compared in terms of efficiency, practicality, and sufficiency. Component and system fragility curve are derived for most proper IMs.