Seismic assessment of a multi-span steel railway bridge in Turkey based on nonlinear time history

In: Natural hazards and earth system sciences: NHESS, Band 18, Heft 1, S. 231-240

Abstract

Abstract. Many research studies have shown that bridges are vulnerable to earthquakes,
graphically confirmed by incidents such as the San Fernando (1971 USA),
Northridge (1994 USA), Great Hanshin (1995 Japan), and Chi-Chi (1999 Taiwan)
earthquakes, amongst many others. The studies show that fragility curves are
useful tools for bridge seismic risk assessments, which can be generated
empirically or analytically. Empirical fragility curves can be generated
where damage reports from past earthquakes are available, but otherwise,
analytical fragility curves can be generated from structural seismic response
analysis. Earthquake damage data in Turkey are very limited, hence this study
employed an analytical method to generate fragility curves for the Alasehir
bridge. The Alasehir bridge is part of the Manisa–Uşak–Dumlupınar–Afyon
railway line, which is very important for human and freight transportation,
and since most of the country is seismically active, it is essential to
assess the bridge's vulnerability. The bridge consists of six 30 m truss
spans with a total span 189 m supported by 2 abutments and 5 truss piers,
12.5, 19, 26, 33, and 40 m. Sap2000 software was used to model the Alasehir
bridge, which was refined using field measurements, and the effect of 60 selected
real earthquake data analyzed using the refined model, considering
material and geometry nonlinearity. Thus, the seismic behavior of Alasehir
railway bridge was determined and truss pier reaction and displacements were
used to determine its seismic performance. Different intensity measures were
compared for efficiency, practicality, and sufficiency and their component
and system fragility curves derived.