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Advances in Concrete Construction
  Volume 14, Number 2, August 2022 , pages 79-92
DOI: https://doi.org/10.12989/acc.2022.14.2.079
 

 open access

Effect of shape and amount of transverse reinforcement on lateral confinement of normal-strength concrete columns
Hyeong-Gook Kim and Kil-Hee Kim

 
Abstract
    The amount and configuration of transverse reinforcement are known as critical parameters that significantly affect the lateral confinement of concrete, the ductility capacity, and the plastic hinge length of RC columns. Based on test results, this study investigated the effect of the three variables on structural indexes such as neutral axis depth, lateral expansion of concrete, and ductility capacity. Five reinforced concrete column specimens were tested under cyclic flexure and shear while simultaneously subjected to a constant axial load. The columns were reinforced by two types of reinforcing steel: rectangular hoops and spiral type reinforcing bars. The variables in the test program were the shape, diameter, and yield strength of transverse reinforcement. The interactive influence of the amount of transverse reinforcement on the structural indexes was evaluated. Test results showed that when amounts of transverse reinforcement were similar, and yield strength of transverse reinforcement was 600 MPa or less, the neutral axis depth of a column with spiral type reinforcing bars was reduced by 28% compared with that of a column reinforced by existing rectangular hoops at peak strength. While the diagonal elements of spiraltype reinforcing bars significantly contributed to the lateral confinement of concrete, the strain of diagonal elements decreased with increases of their yield strength. It was confirmed that shapes of transverse reinforcement significantly affected the lateral confinement of concrete adjacent to plastic hinges. Transverse reinforcement with a yield strength exceeding 600 MPa, however, increased the neutral axis depth of normal-strength concrete columns at peak strength, resulting in reductions in ductility and energy dissipation capacity.
 
Key Words
    lateral confinement; neutral axis depth; plastic hinge; spiral; transverse reinforcement
 
Address
Department of Architectural & Urban System Engineering, Kongju National University, Cheonan 31080, Korea.
 
References
    -acc1402001-
 

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