Determination of Steels in Kentucky Bridges

Monday, December 14, 2020 - 16:15

The Kentucky Transportation Cabinet (KYTC) maintains over two hundred steel bridges constructed with types of steel which are unknown. Kentucky Transportation Center (KTC) researchers have developed a procedure for determining steel tensile properties (0.2% yield strength and ultimate tensile strength) which can be used to help identify unknown steels. The procedure involves extracting small coupons from the lower flanges of steel deck girder bridges. Coupons are then machined into sub-sized tensile testing specimens and suitable shapes for chemical analyses. Sub-sized tensile tests returned values generally comparable to those provided in mill certifications of steels purchased for laboratory trials. Several analytical methods — X-ray fluorescence (XRF) spectroscopy, laser-induced breakdown spectroscopy (LIBS) and arc-spark optical emission spectrometry (OES) — were tested for accuracy against chemical analyses in the mill certifications. All of the methods proved capable of characterizing steel chemistries.

Researchers performed an in-depth review of all obtainable ASTM/AASHO/AASHTO standard structural steel specifications issued from 1900 through 2016. These were incorporated into a spreadsheet along with periodic revisions. Catalogued data include year of specification/revision issuance, material type, thickness, yield and tensile strengths, and steel chemistries (including 15 potential elements). This data set was incorporated into a database management program that can be used by agency officials to devise potential classifications based on ASTM/AASHO/AASHTO standard structural steel specifications.

This report can be downloaded from the University of Kentucky website at


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