Quantification of the Approximations Introduced by Assumptions on the Marginal Distribution of the Demand for Highway Bridge Fragility Analysis

Fragility analysis is one of the most popular tools for the computation of the probability of reaching each investigated limit state for a given value of the external load intensity. Because of its versatility and computational efficiency, fragility analysis is particularly appropriate for regional loss estimations and risk analyses. Several different techniques have been proposed in the literature to compute the fragility of buildings and bridges. However, most of these techniques rely on simplifications and assumptions which, in some cases, are made more for analytical convenience than for adherence to reality. This paper investigates the effect of three of these common assumptions made on the engineering demand parameters for the case of seismic fragility analyses of bridges: (1) the marginal distribution is lognormal, (2) the median of such distribution follows a power law of the seismic intensity measure of choice, and (3) the dispersion of such distribution is constant for any value of the intensity measure. Numerical analyses have been performed running extensive Monte Carlo simulations on computational clusters, focusing on structural models of different complexity. The results suggest that assumption (1) is not realistic in general, but it does not induce a significant error on the final results, whereas assumptions (2) and (3) significantly corrupt the quality of the results, introducing substantial errors. A comprehensive methodology for the assessment of fragility curves for structural components and systems is then proposed, which does not rely on the above-mentioned assumptions.


  • English

Media Info

  • Media Type: Web
  • Pagination: pp 1321-1330
  • Monograph Title: Vulnerability, Uncertainty, and Risk: Quantification, Mitigation, and Management

Subject/Index Terms

Filing Info

  • Accession Number: 01532722
  • Record Type: Publication
  • ISBN: 9780784413609
  • Files: TRIS, ASCE
  • Created Date: Jul 7 2014 3:02PM