Probabilistic Demand Models and Fragility Estimates for Bridges Elevated with Steel Pedestals
Publication: Journal of Structural Engineering
Volume 139, Issue 9
Abstract
Probabilistic seismic demand models are developed for bridges elevated with steel pedestals by adding correction and error terms to commonly used models. Separate probabilistic demand models are developed for the force demand on steel pedestals and the shear and deformation demands on concrete columns. Nonlinear time history analyses on detailed, three-dimensional finite-element models are used to generate virtual experimental data. By applying a Bayesian updating method to the generated data, parameters of the probabilistic models and their correlations are estimated. Comparisons between the demands from the developed probabilistic demand models and the demands from their corresponding demand models without correction and error terms reveal that the developed probabilistic models provide more accurate and unbiased predictions of the demands of interest. As an illustration of the developed framework, fragilities are estimated for a two-span bridge. The results show that pedestals are more vulnerable in the longitudinal direction, and columns are more vulnerable in the transverse direction. A sensitivity analysis on the studied bridges shows that decreasing the pedestal height, increasing the length of the pedestal anchor bolts within the concrete bent, and increasing the concrete cover on the anchor bolts are the most effective ways to decrease the probability of failure.
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Acknowledgments
The authors acknowledge the Texas A&M Supercomputing Facility (http://sc.tamu.edu/) for providing computing resources useful in conducting the research reported in this paper.
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Published In
Journal of Structural Engineering
Volume 139 • Issue 9 • September 2013
Pages: 1515 - 1528
Copyright
© 2013 American Society of Civil Engineers.
History
Received: Mar 5, 2012
Accepted: Sep 12, 2012
Published online: Sep 17, 2012
Published in print: Sep 1, 2013
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