High strength reinforcing steel bars : low-cycle fatigue behavior : final report - part B.

PDFTech ReportFHWA-OR-RD-17-09SPR 762 - Part BHigh strength steelReinforcing barsReinforced concrete bridgesFatigue (Mechanics)OregonOregon. Dept. of Transportation. Research SectionBarbosa, Andr\ue9 R.Trejo, DavidNielson, DrewMazerei, VandadTibbits, CodyOregon State UniversityOregon. Dept. of Transportation. Research SectionUnited States. Federal Highway AdministrationUS Transportation CollectionHigh-strength steel (HSS) reinforcing steel, specifically ASTM A706 Grade 80 (550), is now permitted by the AASHTO LRFD Bridge Design Specifications for use in reinforced concrete bridge components in non-seismic regions. Using Grade 80 (550) reinforcing steel bars instead of Grade 60 (420) reinforcing steel bars reduces material and construction costs. However, state highway agencies (SHAs) only allow Grade 80 (550) reinforcing steel in bridge structural elements that are not expected to undergo large strain reversals (low cycle fatigue) during an earthquake. AASHTO and SHAs have concerns with using Grade 80 (550) reinforcing steel in elements designed for low cycle fatigue due to the lack of experimental data. The report presented details research done on performance of Grade 80 (550) reinforcing steel under low cycle fatigue, which is crucial to provide designers data on cyclic/seismic performance of bridge columns. Low cycle fatigue testing under a universal testing machine uniaxial material testing was performed to compare toughness fatigue life predictions for the four types of reinforcing steel bar (ASTM A615 and ASTM A706 at Grade 60 and Grade 80). Results in this report provide for benchmark test data for ASTM A706 Grade 80 steel bars for use in design of compression members under flexural loading