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Fragility Considerations in Highway Bridge Design

M. Shinozuka, S. Banerjee and S-H. Kim

MCEER-07-0023  | December 14, 2007

This report integrates statistical and analytical methods for the prediction of seismic performance of highway transportation networks. For this purpose, an integrated framework involving the structural engineering module of multilayer simulation scheme is developed. This module is a key component of the performance simulation of such spatially distributed systems. In the analysis, it is assumed that bridges are the only components of the network system vulnerable to earthquake ground motion. Bridge seismic damageability at various damage conditions is expressed in the form of fragility curves associated with the states of minor, moderate, major and collapse damage, mechanistically defined in terms of the extent of ductility rotation of bridge columns at the bottom and top. This report demonstrates the application of fragility curves in the performance-based seismic design of bridges. On the basis of statistical and analytical tools discussed here, a design acceptance criterion is suggested that can verify the target performance level of a newly designed bridge under a prescribed level of seismic hazard.

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