Bridge Deck Replacement for Minimum Expected Cost Under Multiple Reliability Constraints

Mark G. Stewart, University of Newcastle
Allen C. Estes, United States Military Academy
Dan M. Frangopol, University of Colorado at Boulder

Article comments

© American Society of Civil Engineers. The definitive version can be found online at http://dx.doi.org/10.1061/(ASCE)0733-9445(2004)130:9(1414).

NOTE: At the time of publication, the author Allen Estes was affiliated with the United States Military Academy - West Point, NY. Currently, August 2008, he is Head and Professor of Architectural Engineering at California Polytechnic State University - San Luis Obispo.

Abstract

The present paper investigates the effect of limit state selection (strength versus serviceability) on bridge deck life-cycle costs and thus on optimal repair strategies. Such a comparison may then help determine whether safety or functionality (or both) are important criteria when optimizing bridge life-cycle performance and costs. The structural element under consideration is a reinforced concrete bridge deck; namely, a State Highway Bridge in Colorado. Two limit states are considered: ultimate strength and serviceability. The exceedence of either of the limit states considered herein will result in deck replacement; namely, if the reliability index falls below a target reliability index or if widespread cracking and spalling occurs. The life-cycle cost analysis includes expected replacement costs as well as the random variability of material properties, loads, section dimensions, model errors, chloride penetration, and corrosion rates. Life-cycle costs can then be compared for strength and serviceability limit state violations. Life-cycle costs for deck replacement based on a serviceability limit state were generally larger than those obtained for the strength limit states. Hence, an unrealistically optimistic life-cycle cost will result when serviceability is not included in the analysis.