Dimitrios Kalliontzis, Waleed Khan, Samvid Parajuli, and Omar Khalid
i Assistant Professor, University of Houston, Houston, Texas, United States, dkallion@central.uh.edu
ii Graduate Student, University of Houston, Houston, Texas, United States, mkhan88@CougarNet.uh.edu
iii Graduate Student, University of Houston, Houston, Texas, United States, sparaju2@CougarNet.uh.edu
iv Formerly at the University of Houston as a Graduate Student, Houston, Texas, United States, onkhalid@CougarNet.uh.edu
ABSTRACT
In the United States, the adoption of high-strength non-prestressed reinforcing bars (HSRBs) in design was initiated by the reinforced concrete industry through ACI 318. The adoption was motivated by several factors including the ability to increase bar spacings, reduce steel congestion, reduce construction materials and costs, and minimize the building carbon footprint. It appears that this trend is continuing with the increasing availability of reinforcement of higher grades, making it imperative that the masonry industry be able to adapt. To ensure that the masonry industry adapts to these new developments, the University of Houston has embarked on a research program to investigate the feasibility of HSRBs in structural masonry design. This paper presents an overview of this program and current findings. So far, the program has completed a series of laboratory tests to evaluate existing TMS 402/602-22 provisions on lap-splice length and flexural design. Lap-splice tests indicated the need to incorporate a reinforcement grade factor of 1.15 for Grade 80 bars in the existing provisions. Lap-splice tests also showed the need to revisit the accuracy of the reinforcement size factor, as it is conservative for smaller and liberal for larger bar diameters. Out-of-plane wall tests were used to evaluate the flexural behavior of masonry walls with longitudinal HSRBs. The test results indicated that TMS 402/602-22, modified to account for Grade 80 bars, can provide satisfactory estimates of nominal strength with sufficient conservatism with respect to the experimental responses. Finally, the research program has performed several prototype beams, columns, walls, and fullscale building designs to investigate the potential benefits of utilizing HSRBs in masonry construction. Findings showed that reductions in reinforcing material costs can reach 25% by using Grade 80 versus Grade 60 bars. These benefits can be further increased considering reductions in material weights and cell grouting.
KEYWORDS: High-strength steel, Grade 80, ASTM 706, ASTM 615, lap splice, flexure, concrete masonry, clay brick.
002-Kalliontzis.pdf
