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Structural Engineering and Mechanics
  Volume 29, Number 6, August20 2008, pages 689-707
DOI: http://dx.doi.org/10.12989/sem.2008.29.6.689
 


Earthquake risk assessment of seismically isolated extradosed bridges with lead rubber bearings
Dookie Kim, Jin-Hak Yi, Hyeong-Yeol Seo and Chunho Chang

 
Abstract
    This study presents a method to evaluate the seismic risk of an extradosed bridge with seismic isolators of lead rubber bearings (LRBs), and also to show the effectiveness of the LRB isolators on the extradosed bridge, which is one of the relatively flexible and lightly damped structures in terms of seismic risk. Initially, the seismic vulnerability of a structure is evaluated, and then the seismic hazard of
a specific site is rated using an earthquake data set and seismic hazard maps in Korea. Then, the seismic risk of the structure is assessed. The nonlinear seismic analyses are carried out to consider plastic
deformation of bridge columns and the nonlinear characteristics of soil foundation. To describe the nonlinear behaviour of a column, the ductility demand is adopted, and the moment-curvature relation of a
column is assumed to be bilinear hysteretic. The fragility curves are represented as a log-normal distribution function for column damage, movement of superstructure, and cable yielding. And the seismic
hazard at a specific site is estimated using the available seismic hazard maps. The results show that in seismically-isolated extradosed bridges under earthquakes, the effectiveness of the isolators is much more noticeable in the columns than the cables and girders.
 
Key Words
    seismic fragility; seismic hazard; seismic risk; LRB seismic isolator; extradosed bridge.
 
Address
Dookie Kim: Dept. of Civil and Environmental Engineering, Kunsan National University, Kunsan, Jeonbuk 573-701, Korea
Jin-Hak Yi: Coastal Engineering Research Department, Korea Ocean Research and Development Institute, Ansan, Gyeonggi 426-744, Korea
Hyeong-Yeol Seo: Dept. of Civil and Environmental Engineering, Kunsan National University, Kunsan, Jeonbuk 573-701, Korea
Chunho Chang: Dept. of Civil Engineering, Keimyung University 1000 Sindang, Dalseo, Daegu 704-701, Korea
 

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