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Structural Concrete Design with High-Strength Steel Reinforcement

Reis, Jonathan M.

Abstract Details

2010, MS, University of Cincinnati, Engineering : Civil Engineering.

This report provides an evaluation of existing AASHTO LRFD Design Specifications relevant to the use of high-strength reinforcing steel and other grades of reinforcing steel having no discernable yield plateau. The report identifies aspects of reinforced concrete design and of the Specifications that may be affected by the use of high-strength reinforcing steel. An integrated experimental and analytical program intended to develop the data required to permit the integration of high-strength reinforcement into the LRFD Specifications is presented. In addition, a number of ‘proof tests’ intended to validate existing Specifications provisions applied to higher-strength reinforcing steel are presented.

The analytical portion of this report surrounds flexural behavior of concrete members reinforced with high-strength steel and other steels which lack a well-defined yield point. One aspect focuses on identifying an appropriate steel strength and/or stress-strain model to capture the behavior of high-strength reinforcing steel while respecting the tenets of design. A value of yield strength, fy, not exceeding 100 ksi is found to be permissible without requiring significant changes to the Specifications. It is also recommended that yield strength be determined based on the stress corresponding to a strain of 0.0035 rather than at a strain of 0.005 or the 0.2% offset approach. Parametric studies suggest less statistical variation using this method and that member capacities are computed conservatively for the range of reinforcement ratios and concrete compressive strengths encountered in practice.

One other aspect of the analytical program evaluates current strain limits defining tension-controlled and compression-controlled behavior of reinforced concrete. New strain limits are developed for high-strength reinforcing steel which reflect an equal amount of ductility captured by the existing strain limits in their application to Grade 60 reinforcement. It is recommended that the strain limits defining tension- and compression-controlled behavior in concrete members reinforced with high-strength steel be set at 0.008 and 0.004, respectively.

The focus of the experimental phase of this study is the use of ASTM A1035 reinforcing steel since it captures both behavioral aspects of interest, i.e., high-strength and no yield point. Three facets of reinforced concrete design are examined: flexural behavior in which A1035 steel is used as longitudinal reinforcement, shear behavior in which A1035 steel is used as transverse reinforcement, and development length of spliced A1035 longitudinal bars. The flexural behavior is found to be adequate under the prescribed strain limits and as designed using fy = 100 ksi. Also, deflections and crack widths exhibited in the flexural members are predictable according to current computation procedures. Shear behavior of high-strength steel is also adequate when designed for the prescribed yield strength. Current AASHTO LRFD development length equations are conservative for determining splice length in ASTM A1035 reinforcing steel.

Bahram Shahrooz, PhD (Committee Chair)
Richard Miller, PhD (Committee Member)
Julienne Cromwell, MS (Committee Member)
394 p.

Recommended Citations

Citations

  • Reis, J. M. (2010). Structural Concrete Design with High-Strength Steel Reinforcement [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1277124990

    APA Style (7th edition)

  • Reis, Jonathan. Structural Concrete Design with High-Strength Steel Reinforcement. 2010. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1277124990.

    MLA Style (8th edition)

  • Reis, Jonathan. "Structural Concrete Design with High-Strength Steel Reinforcement." Master's thesis, University of Cincinnati, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1277124990

    Chicago Manual of Style (17th edition)