Iowa Department of Transportation
Brent Pharesbphares@iastate.edu email >
Bridge Research Engineer
Jay Shenjshen@iastate.edu email >
About the research
ASTM A1010 steel is a nominal 12% chromium (10.5% minimum and 12.5% maximum) steel reported to have enhanced corrosion resistance compared to traditional painted structural steels, weathering steels, and galvanized steels. In 2016, the Iowa Department of Transportation (DOT) built a four-span bridge partially constructed using A1010 steel.
Despite the wealth of information on the durability of A1010 steel in corrosive environments, the literature had a gap concerning how this steel responds to the loads that bridge structures experience during their service lives. To investigate this and facilitate the future use of A1010 steel, this study devised a holistic structural testing program.
A 52 ft 9 in. long girder was designed, fabricated, and tested (while subjected to four-point bending), with the results further compared to the current American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) Bridge Design Specifications. Additionally, tensile and fatigue tests were conducted to obtain the mechanical and fatigue behavior for A1010 steel. Furthermore, live load tests for the A1010 bridge were conducted to identify any changes in behavior that occurred with time. Also, data were analyzed for differences in response between the A1010 and A709 steel girders. The research resulted in the following conclusions from the laboratory and field results:
- The predictions obtained utilizing actual material properties were reasonable compared to the results obtained from the laboratory test, which indicates the A1010 girder’s ability to meet AASHTO design requirements.
- No apparent differences were observed between the A1010 and A709 girders during field testing. Additionally, for all load cases, the maximum measured distribution factors were less than those calculated using the AASHTO equations.
- The live-load tests performed on the A1010 steel bridge over two years indicated that the changes in structural performance were minimal.
Long-term monitoring of an A1010 steel cross frame and a research panel will be carried out to provide essential information on galvanic corrosion throughout the serviceable lifetime of the bridge. The results will help in understanding the importance of controlling and reducing galvanic corrosion for future A1010 steel bridges in the region.