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theses

Bridges are an important part of the nation’s infrastructure and due to the limited budgets available to keep them properly maintained, the methods of evaluation and damage identification must improve in accuracy and cost-effectiveness. For the industry of bridge evaluation and damage identification the research area that provides the greatest potential is multi-modal non-destructive testing (NDT). A multi-modal NDT approach to condition assessment allows for the identification of several different deterioration states, in turn providing a more complete condition assessment. Research was conducted to develop a methodology and program to convert multi-modal NDT data from bare reinforced concrete bridge decks into a condition-based assessment. The NDT methods utilized were electrical resistivity (ER), half-cell potential (HCP), ground penetrating radar (GPR), impact echo (IE), and chain drag (CD). Data for each of these methods was collected on 12 bridge decks located in various geographic locations. Correlations were identified between the NDT methods so as to better understand the relationship between the methods and concrete deterioration. Some of the identified correlations include a strong association of low cover depth with deterioration, ER and HCP measurements being highly related, and GPR attenuation associated with locations of deterioration identify by ER, HCP, and CD. The identified correlations were used to develop a statistics-based approach to threshold identification for ER, HCP, and GPR. Threshold values are highly relative; therefore, a statistical approach provides a more effective and robust threshold identification methodology. Using the identified thresholds, the multi-modal NDT data was fused and converted into a deterioration-based condition assessment that identifies locations of corrosive environment, active corrosion, delamination/lateral cracking, and severe delamination. The condition assessment program also rates the bridge decks using established and federally mandated rating systems created by the National Bridge Inventory and American Association of State Highway and Transportation Officials. This research resulted in a more effective multi-modal NDT condition assessment of bridge decks. Improved multi-modal NDT will provide bridge owners and maintenance personnel an improved tool to assess bridge decks and to make decisions regarding their maintenance.

ETD_5445

Ph.D.

Includes bibliographical references

by Brian M. Pailes

doi:10.7282/T34M92V0

ETD doctoral

The author owns the copyright to this work.