Bridge Deck Replacement for Minimum Expected Cost Under Multiple Reliability Constraints

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. CE Database subject headings: Corrosion; Limit states; Life cycle cost; Reliability; Concrete; Bridge decks; Rehabilitation;