Experimental Behavior of Concrete Columns Reinforced with Thermomechanically Treated and Cold-Twisted Ribbed Steel Bars

• Type: Article in International Scientific Journal
• Date: 2025

Authors

Khan, MS (Author) Other; Rafi, MM (Author) Other; Humberto Varum (Author) FEUP

Journal

Title: ACI Structural Journal

Vol. 122

Pages: 57-70

ISSN: 0889-3241

Publisher: American Concrete Institute

Indexing

ISI Web of Knowledge - 0 Citations

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Other information

Authenticus ID: P-018-HHE

DOI: 10.14359/51744392

Abstract (EN): This paper presents experimental testing results on full-scale reinforced concrete (RC) column specimens subjected to quasi-static cyclic loading. Two types of lap-spliced steel reinforcing bars were used: hot-rolled thermomechanically treated (TMT) and coldtwisted ribbed bars. The specimens were tested under varying axial load levels: CD-10 and CD-20 specimens, reinforced with TMT bars, were loaded at 10% and 20% of the columns' axial load capacity, respectively, while the CT-20 specimen, reinforced with cold-twisted ribbed bars, was axially loaded at 20% capacity. In contrast to the cold-twisted bars, the TMT bars'yield strength exceeded the specified strength by 38%, leading to an underestimation of the required reinforcing bar splice length and significantly impacting cracking patterns and curvature near the dowel end. The CD-20 and CT-20 specimens showed comparable lateral load capacity and initial stiffness, substantially higher than the CD-10 specimen. The CT-20 specimen exhibited symmetrical hysteretic behavior, indicating a consistent response to reversed cyclic loading, with (on average) 10% and 45% higher peak and ultimate displacement capacity than CD-10 and CD-20, respectively, and 45% higher displacement ductility capacity. Notably, only the CT-20 specimen met the acceptance criteria for structural testing described by the code of practice, while the lower ductility and ultimate rotation capacity of CD-10 and CD-20 resulted from the unintended increase in reinforcing bar yield strength.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 14