• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.6
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• pp.1-8
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• 2012

This study estimates the performance of confined concrete according to the configuration of transverse steel bars. The main test variables were the yield strength of spiral reinforcement and configuration of transverse reinforcement. A total of 27 specimens with rectangular cross section were cast and tested under monotonic concentric compression. R-type specimens with rectangular spirals, C-type specimens with circular spirals and O-type specimens with combined shape of rectangular and octagon were designed in this study. From experimental results, it is concluded that the proposed configuration of transverse reinforcement can provided improved ductility to the confined concrete compared to rectangular spiral reinforcement.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.15-16
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• 2009

The purpose of this research is to examine the confinement effect of high-strength transverse reinforcement for concrete cylinders. In this study the behavior of concrete cylinders reinforced with high-strength steel spirals was investigated.

• Journal of the Korea Concrete Institute
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• v.21 no.3
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• pp.311-318
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• 2009

An experimental investigation was conducted to examine the hysteretic behaviors of ultra-high strength concrete tied columns. The purpose of this study is to propose the volumetric ratio of transverse reinforcement for ultra-high strength concrete tied columns with 100 MPa compressive strength. Nineteen 1/3 scaled columns were fabricated to simulate an 1/2 story of actual structural members with the main variables of axial load ratio, configurations and volumetric ratios of transverse reinforcement. The results show that the deformability of columns are affected by the configurations and volumetric ratios of transverse reinforcement. Especially, it has been found that the behavior of columns are affected by axial load ratio rather than the amounts and the configurations of transverse reinforcement. To improve the ductility behavior of RC column using ultra high strength concrete in a seismic region, We suggested the amount of transverse reinforcement for all data that satisfy the required displacement ductility ratio over 4. It is means that the lateral confining reduction factor (${\lambda}^c$) considering the effective legs, configuration and spacing of transverse reinforcement and axial load ratio was reflected for the volumetric ratio of transverse reinforcement.

• Magazine of the Korea Concrete Institute
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• v.7 no.2
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• pp.146-154
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• 1995

I n this paper, an experimental research was carried out to investigate the confinement effect of spiral reinforcements in concrete column specimens subjected to t.he concentric axial corn pressive loads. Main variables were the compressive strengths of concrete of 27.2, 62.4 and 81.2 MPa, and the spacings of spirals of 120, 60, 40, 30, 25 and 20mm. and the yield strengths of spir als of 451 and 1375MPa, respectively. For the same volumetric ratio and yield strength of spir als, it was shown that the strength increment of confined concrete was almost same regardless of the strength of unconfined concrete, however, the axial stram at maximum stress was decreas ed with increasing of the compressive strength of unconfined concrete.

• Journal of the Korea Concrete Institute
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• v.22 no.3
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• pp.357-366
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• 2010

This paper presents experimental results about shear wall with various lateral reinforcement details in boundary elements. The research objective is to study the structural behavior of shear wall with boundary column confined by rectangular spiral hoops and headed cross ties developed to improve workability in the fabrication of boundary columns. These two details can be fabricated in a factory and put together on-site after being delivered so that the construction work may be reduced. Main parameters in the experimental study were the types of hoop and cross tie: rectangular spiral hoop and headed cross tie vs. standard hoop and cross tie with hook. Four half scaled shear wall specimens with babel shape were made and tested by applying horizontal cyclic load under constant axial force, 10% of nominal compressive strength of concrete. Based on the test result, it was shown that the shear wall with rectangular spiral hoop and headed cross tie in boundary columns has structural capacity compatible with conventional shear wall. The specimen SW-Hh which has bigger hoop bar and higher volumetric ratio of transverse reinforcements than other showed improved energy dissipating characteristic but it presented a rapid reduction of strength after peak point. The results indicates that, it is necessary to consider volumetric ratio of transverse reinforcements as well as hoop space in designing of shear wall with boundary columns for improved strength and ductility.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.855-858
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• 2008

A compression lap splice can be calculated longer than a tension lap splice in high strength concrete according to current design codes. Including effects of transverse reinforcement, a compression splice becomes much longer than a tension splice. Effects of transverse reinforcement on strength and behavior of compression lap splice, which always exist in actual structures, have been investigated through experimental study of column tests with concrete strength of 40 and 60 MPa. Confined specimens have twice of calculated strengths by current design codes. New design equations for the compression lap splice including the effects of transverse reinforcement are required for practical purpose of ultra-high strength concrete. End bearing is enhanced by transverse reinforcement placed at ends of splice not by transverse reinforcement within splice length. As more transverse reinforcement are placed, the stresses developed by bond linearly increase. The transverse reinforcements at ends of splice a little improve the strength by bond.

• Journal of the Korea Concrete Institute
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• v.17 no.4 s.88
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• pp.505-511
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• 2005

This experimental investigation was conducted to examine the seismic performance of reinforced concrete bridge columns. The columns were subjected to a constant axial load and a cyclic horizontal load-inducing reversed bending moment. The variables studied in this research were the volumetric ratios of transverse reinforcement (ps=0.96, 1.44 percent) and axial load ratios (P/Po=0.05, 0.1, 0.2) and concrete strengths (35, 60MPa). Test results showed that bridge columns with $44\%$ higher amounts of transverse reinforcement than that required by seismic provisions of ACI 318-02 showed ductile behavior. For bridge columns with axial load ratio(P/Po) less than 0.2, the ratio of $M_{max}\;over\;M_{ACI}$, nominal moment capacity predicted by ACI 318-02 provisions, was consistently greater than 1 with approximately a $20\%$ margin of safety.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.1
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• pp.58-66
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• 2022

In this study, to examine the effect of the transverse thermal expansion behavior of FRP reinforcing bars and concrete on the concrete cover thickness, based on 20℃, when the temperature changes from -70℃ to 80℃, the behavior of concrete was studied theoretically and numerically. Theoretical elastic analysis and nonlinear finite element analysis were performed on FRP reinforced concrete with different diameters and cover thicknesses of FRP reinforcement. As a result, at a negative temperature difference, concrete was compressed, and the theoretical strain result and the finite element result were similar, but at a positive temperature difference, tensile stress and further cracks occurred in the concrete, which was 1.2 to 1.4 times larger than the theoretical result. The ratio of the diameter of the FRP reinforcing bar to the thickness of the concrete cover (c/db) is closely related to the occurrence of cracks. Since the transverse thermal expansion coefficient of FRP reinforcing bars is three times greater than that of concrete, it is necessary to consider this in design.

• Journal of the Korea Concrete Institute
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• v.15 no.2
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• pp.297-304
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• 2003

This paper presents the test results of RCS(Reinforced Concrete Steel) beam-column joint with various types of transverse reinforcements such as small-column-type transverse reinforcements, four-piece ㄱ-shape assembled hoops and four-piece ㄱ-shape welded hoops. Five interior beam-column joint specimens were tested to examine the seismic performance and the shear strengths. From the test results, it was found that all the specimens sustained their strength at large levels of story drift(${\theta}$=0.035) without significant loss of strength and stiffness. Therefore it was concluded that the seismic performance and shear strength of the proposed RCS joint are at least the same as those of the specimen with conventional reinforcing details. Also, the contribution of the outer panel to the shear strength of the joint should be evaluated by the compression strut mechanism rather than compression field mechanism.

• Land and Housing Review
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• v.6 no.1
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• pp.11-19
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• 2015

This paper presents experimental results on detailing of boundary element transverse reinforcement, proposed to alleviate placement detailing of special shear wall experiencing difficulty in construction at the sites due to recently reinforced seismic regulations, according to the type and placement interval of transverse reinforcement. As a result of experiment, crack and destruction aspects of SSWR series specimen that employed the proposed detailing of transverse reinforcement showed similar trend as SSW series specimen that used closed hoop. Predicted maximum strength values were exceeded. Also as a result of comparing energy dissipation ability, SSWR2 specimen that follows alleviated placement detailing was found to have similar seismic performance as special shear wall SSW2 specimen based on the existing design standard. As it satisfies the deformation angle condition of 1.5% provided in the design standard, SSWR2 can be used as the main lateral force resistance element in structures.