American Society of Civil Engineers

Mitigating Epistemic Uncertainty in Structural Identification: Case Study for a Long-Span Steel Arch Bridge

by Qin Pan, (Civil Engineer, Bechtel Power Corporation, 5275 Westview Dr., Frederick, MD 21703. E-mail:, Kirk Grimmelsman, (Assistant Professor, Dept. of Civil Engineering, Univ. of Arkansas, Fayetteville, AR 72701.), Franklin Moon, (corresponding author), (Assistant Professor, Dept. of Civil, Architectural and Environmental Engineering, Drexel Univ., Philadelphia, PA 19104), and Emin Aktan, (John Roebling Professor and Director of the Drexel Intelligent Infrastructure Institute, Drexel Univ., Philadelphia, PA 19104.)

Journal of Structural Engineering, Vol. 137, No. 1, January 2011, pp. 1-13, (doi:

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Document type: Journal Paper
Abstract: Characterization of constructed civil-engineering systems through structural identification (St-Id) has gained increasing attention in recent years due to its potential to enable more effective infrastructure asset management and performance-based engineering. Although there have been recent advances that mitigate the challenges posed by aleatory (random) uncertainty, there are many remaining challenges associated with epistemic (bias) uncertainty that often have a more critical impact on the reliability of St-Id (especially with applications to constructed systems). The objective of this paper is to illustrate various sources of epistemic uncertainty and describe mitigation approaches by detailing the St-Id of a long-span steel arch bridge. This application includes a priori modeling, ambient vibration monitoring, data processing, feature extraction, and finite-element (FE) model correlation. Following a description of the St-Id, the impact of various modeling uncertainties on the calibrated FE model is evaluated by comparing different identification scenarios. Finally, a simple and rational approach to "truth testing" the identified model is developed and employed to determine its admissibility.

ASCE Subject Headings:
Arch bridges
Case studies
Field tests
Finite element method
Span bridges
Steel bridges
Uncertainty principles

Author Keywords:
Field test
Finite-element modeling