The following report details a research project comprised of two phases. Phase I included the full-scale experimental testing of two built-up truss chord members removed from service. The members were installed into a reaction frame and loaded to failure to determine remaining capacity in the presence of pack rust, as well as after-failure load redistribution behavior mimicking the member in a state following complete fracture of half the cross section. Phase I also included a finite element–based parametric study calibrated by the experimental work. The study was focused on two-channel axially loaded members for the purpose of developing closed-form solutions intended for evaluation of internal member redundancy. During Phase II of the project, a small round-robin-style inspection and load rating study was performed with certified bridge inspectors and practicing load rating engineers. The purpose was to investigate the variability in the inspection and evaluation of severely corroded steel tension members. This process evaluated two separate, but related, sources of variability within the inspection and load rating process. The variability in each task was controlled such that variability in the load ratings was not compounded by variability in the inspection findings.


steel bridge, fatigue, fracture, internal member redundancy, corrosion, inspection, variability of inspection results, pack rust, built-up member

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