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Structural Engineering and Mechanics Volume 65, Number 5, March10 2018 , pages 633-644 DOI: https://doi.org/10.12989/sem.2018.65.5.633 |
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Component fragility assessment of a long, curved multi-frame bridge: Uniform excitation versus spatially correlated ground motions |
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Jong-Su Jeon, Abdollah Shafieezadeh and Reginald DesRoches
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| Abstract | ||
| This paper presents the results of an assessment of the seismic fragility of a long, curved multi-frame bridge under multi-support earthquake excitations. To achieve this aim, the numerical model of columns retrofitted with elliptical steel jackets was developed and validated using existing experimental results. A detailed nonlinear numerical model of the bridge that can capture the inelastic response of various components was then created. Using nonlinear time-history analyses for a set of stochastically generated spatially variable ground motions, component demands were derived and then convolved with new capacity-based limit state models to obtain seismic fragility curves. The comparison of failure probabilities obtained from uniform and multi-support excitation analyses revealed that the consideration of spatial variability significantly reduced the median value of fragility curves for most components except for the abutments. This observation indicates that the assumption of uniform motions may considerably underestimate seismic demands. Moreover, the spatial correlation of ground motions resulted in reduced dispersion of demand models that consequently decreased the dispersion of fragility curves for all components. Therefore, the spatial variability of ground motions needs to be considered for reliable assessment of the seismic performance of long multi-frame bridge structures. | ||
| Key Words | ||
| long, curved multi-frame bridge; nonlinear numerical bridge model; spatially variable ground motions; multi-support excitation analysis; component fragility curves | ||
| Address | ||
| Jong-Su Jeon: Department of Civil Engineering, Andong National University, 1375 Gyeongdong-ro, Gyeongsangbuk-do 36729, Republic of Korea Abdollah Shafieezadeh: Department of Civil, Environmental and Geodetic Engineering, The Ohio State University, 2070 Neil Ave., Columbus, OH 43210, USA Reginald DesRoches: Department of Civil and Environmental Engineering, Rice University, 6100 Main Street, Houston, TX 77005, USA | ||