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Steel corrosion on bridges and ancillary structures due to environmental effects and deicing chemicals is a serious problem for Minnesota's infrastructure. The ability to detect; locate; and measure corrosion is an important aspect of structure inspection. Accurate thickness measurements and corrosion mapping are essential for determining load capacity of structural members on bridges and ancillary structures. The Minnesota Department of Transportation purchased an OmniScan Phased Array Corrosion Mapping System. Unlike conventional ultrasonic equipment; this system provides detailed three-dimensional images of structural members including the remaining section of members that exhibit corrosion. This gives engineers better tools to visualize and evaluate the condition of bridges than was previously possible. With the future purchase of additional transducers; the OmniScan can also be used for enhanced inspection of welds and bridge pins.

MnDOT has identified the need to develop a methodology to quantify when a steel bridge system is considered fracture critical based on Federal Highway Administration recommendations. The overall goal of this project was to research existing applicable fracture critical research papers and publications, develop a methodology for determining whether a bridge is fracture critical or not based on this research, then apply this methodology to six different fracture critical steel pier caps as a refined analysis. This refined analysis used advanced computer modeling software to develop a 3-D model of the bridge, and then simulated localized failure modes at the fracture critical steel pier caps. These simulated failures were used to determine the adequacy of load path redundancy to the remaining portion of the bridge and whether a catastrophic failure of the entire bridge would occur.