Development of Large High-Strength Headed Reinforcing Bars
Development of Large High-Strength Headed Reinforcing Bars
This research expands the available data on the anchorage strength of high-strength headed reinforcing bars to include the largest sizes currently permitted in the ACI Building Code, No. 14 and No. 18, and use those results to verify the applicability of the currently proposed design criteria. Headed reinforcement is permitted under the provisions of ACI 318. Those provisions, however, limit the bar size to No. 11 and smaller. The study includes headed bars in concrete with nominal compressive strengths ranging from 5,000 to 16,000 psi to produce stresses in the bars at anchorage failure ranging from 55 to 148 ksi. Bar spacing ranges from 3 to 10 bar diameters. Heads with bearing areas and multiple configurations matching those permitted in practice are tested. A limited number of tests are also be performed on large-size hooked bars to determine if the relationship developed in previous tests, indicating that headed bar anchorage length equals approximately 80% of that for hooked bars, is appropriate for the largest size bars.
Results of the tests will be used to propose modifications to current code provisions with the goal of broadening the application of headed bars and significantly reducing congestion in reinforced concrete members. This final report describes the test methods, test results, and development of the design criteria and recommendations.
Project Co-funders: ACI Foundation $50,000, BarSplice Products $45,000, Headed Reinforcement Corporation $45,000, nVENT Lenton, CRSI Education and Research Foundation $45,000, Precast/Prestressed Concrete Institute $25,000
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Grant Details
ProjectDevelopment of Large High-Strength Headed Reinforcing BarsGranteeUniversity of KansasCategoryConcreteSubcategoryHigh-Strength RebarGrant #05-18Award Amount$380,000Grant PeriodAugust 2018 - July 2023Grant StatusCompletePrincipal InvestigatorsDavid Darwin, Professor, University of Kansas; Matthew O’Reilly, Associate Professor, University of Kansas; Rémy D. Lequesne, Associate Professor, University of Kansas; Andres Lepage, Professor, University of KansasIndustry ChampionsDominic Kelly, Simpson Gumpertz & Heger; Ron Klemencic, Magnusson Klemencic and Associates; Jack Moehle, University of California, Berkeley; Amy Trygstad, CRSI; Javeed Munshi, Bechtel; Andrew Taylor, KPFF Consulting EngineersCPF AlliesCRSI Education and Research Foundation (CRSI), ACI Foundation, BarSplice Products, Headed Reinforcement Corporation, nVENT Lenton, Precast/Prestressed Concrete Institute, Commercial Metals Company, Nucor Corporation -
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