• Journal of the Korea institute for structural maintenance and inspection
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• v.3 no.3
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• pp.139-147
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• 1999

Six reinforced concrete shear wall, constructured with fully rigid, slit, and infilled types, were tested under both vertical and cyclic loadings. Experimental programs were carried out to evaluate the seismic performance of such test specimens, such as the hysteretic behavior, the maximum horizontal strength, crack propagation, and ductility, under load reversals. All the specimens were modeled in one-third scale size. Based on the test results, the following conclusions can be made. For the diagonal reinforced slit and infilled shear wall specimens, it was found that the failure mode shows very effective crack control and crushing due to slippage prevention of boundary region and reduction of diagonal tension rathar than the brittle shear and diagonal tension failure. The ductility of specimens designed by the diagonal reinforcement for the slit and infilled shear wall was increased 1.72~1.81 times in comparison with the fully rigid shear wall frame. Maximum horizontal load-carrying capacity of specimens designed by the diagonal reinforcement ratio the slit and infilled shear wall was increased respectively by l.14 times and l.49 times in comparison with the standard fully rigid shear wall frame.

• Journal of Korean Association for Spatial Structures
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• v.17 no.1
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• pp.59-67
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• 2017

In this study, load transfer tests based on KCI-PS101 were conducted to verify the performance of spiral anchorage zone reinforcement for banded post-tensioning (PT) monostrands. With results, the compressive strength of spiral reinforcement was increased by about 20% than that of specimens with two horizontal steel bars and 8% than that of U-shaped bars. Advanced spiral reinforcement for corner increases compressive strength and can resist the spalling forces or fall-out effect at the corner by shear. The ratio of maximum load to amount of steel of the spiral reinforcement is about twice than that of U-shaped reinforcement. With increase of compressive strength capacity and improvement of constructability, the spiral reinforcement is considered to have advantages of promoting the performance of PT anchorage zone compared to conventional methods.

• Journal of Korean Association for Spatial Structures
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• v.18 no.3
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• pp.117-124
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• 2018

In the post-tensioned concrete member, additional reinforcement is required to prevent failure in the anchorage zone. In this study, the details of reinforcement suitable for the anchorage zone of the post-tensioned concrete member using circular anchorage was proposed based on the experimental results. The tests were conducted with the compressive strength of concrete and reinforcement types as variables. The experimental results indicated that the additional reinforcement for the anchorage zone is required when the compressive strength of concrete is less than 17.5 MPa. U-shaped reinforcement shows most effective performance in terms of maximum strength and cracks patterns.

• Nuclear Engineering and Technology
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• v.54 no.2
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• pp.732-740
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• 2022

A piping system stress analysis need to be re-performed for structural integrity assessment after reinforcement of a pipe with significant wall thinning. For efficient stress analysis, a one-dimensional beam element for the wall-thinned pipe with reinforcement needs to be developed. To develop the beam element, this work presents analytical equations for elastic stiffness of the wall-thinned pipe with reinforcement are analytically derived for axial tension, bending and torsion. Comparison with finite element (FE) analysis results using detailed three-dimensional solid models for wall-thinned pipe with reinforcement shows good agreement. Implementation of the proposed solutions into commercial FE programs is explained.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.1
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• pp.101-110
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• 2014

Expansion agent is a very effective admixture for prevention of cracking due to autogenous/drying shrinkage and this can induce internal chemical prestress to embedded reinforcement. In this paper, tension-softening and hardening in cement mortar with steel and CSA expansion agent are experimentally evaluated. Cement mortar with steel reinforcement is prepared and tensile strength test is performed for evaluation of cracking and tensile behavior. In spite of slightly reduced strength and elasticity in CSA mortar, significantly increased tension-hardening behavior is evaluated in CSA mortar with induced chemical prestress. Furthermore previous tension softening models are compared with the test results and improvement are proposed.

• Journal of the Korea Institute of Building Construction
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• v.19 no.1
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• pp.47-57
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• 2019

The purpose of this study is to evaluate the improvement effect of adhesion in tension and flexure of polymer cement mortars that have widely used as a repair-reinforcement material in construction field according to adding of polymer dispersions depending on different three types test methods. From the test results, the adhesion performance is improved with a raise in polymer-cement ratio irrespective of the type of polymer. The maximums of A type adhesion in tension, B type adhesion in tension and adhesion in flexure show 1.90 times, 2.17 times and 1.83 times, respectively that of plain cement mortar. The relative strength ratios, B type adhesion in tension and adhesion in flexure of polymer cement mortars to tensile and flexural strengths of plain mortar respectively are in ranges of 50.1% to 101.7% and 73.8% to 132.9% compared to 46.9% of plain mortar. It is apparent that polymer cement mortars with EVA and polymer cement ratios of 10% to 15% are recommended considering its adhesion performance and cost as a repair-reinforcement material in construction field.

• 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.22 no.6
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• pp.859-866
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• 2010

To overcome weak and brittle tensile characteristics of concrete, many studies have been conducted on fiber reinforced concrete (FRC). Recently, high performance fiber reinforced cementitious composites (HPFRCC), which shows strain hardening behavior, has been actively investigated. However, most of the studies focused on the material behavior of HPFRCC itself. Only a few studies have been conducted on the tensile behavior of HPFRCC with steel reinforcement. Therefore, a tension stiffening test for HPFRCC members has been conducted in this study in order to investigate the effect of a reinforcing bar on the tensile behavior of HPFRCC. Tensile stress-strain relationship of HPFRCC has been derived from the tests. The HPFRCC resisted tensile stress continuously from the first cracking to the yield of reinforcing bar. Through the comparison with the tensile behavior of HPFRCC members without a reinforcement, it was shown the tensile strength and capacity of HPFRCC were reduced due to the combined effect of the high shrinkage of HPFRCC, restraining effect of steel reinforcement, and the strain hardening behavior of HPFRCC. It is expected that the tension stiffening test results can be useful for an application of HPFRCC with steel reinforcement as structural members.

• Journal of the Korea Concrete Institute
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• v.26 no.2
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• pp.143-150
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• 2014

To avoid abrupt torsional failure due to concrete crushing before yielding of torsional reinforcement and control the diagonal crack width, design codes specify the limitations on the yield strength of torsional reinforcement of RC members. In 2012, Korean Concrete Institute design code increased the allowable maximum yield strength of torsional reinforcement from 400 MPa to 500 MPa based on the analytical and experimental research results. Although there are many studies regarding the shear behavior of RC members with high strength stirrups, limited studies of the RC members regarding the yield strength of torsional reinforcement are available. In this study, twelve RC beams having different yield strength of torsional reinforcement and compressive strength of concrete were tested. The experimental test results indicated that the torsional failure modes of RC beams were influenced by the yield strength of torsional reinforcement and the compressive strength of concrete. The test beams with normal strength torsional reinforcement showed torsional tension failure, while the test beams with high strength torsional reinforcement greater than 480 MPa showed torsional compression failure. Therefore, additional analytical and experimental works on the RC members subjected to torsion, especially the beams with high strength torsional reinforcement, are needed to find an allowable maximum yield strength of torsional reinforcement.

• KCI Concrete Journal
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• v.14 no.3
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• pp.102-110
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• 2002

Results of an experimental study on the pullout behavior of the headed reinforcement are presented. A total of 48 pullout tests was performed to evaluate pullout strengths and load-displacement behaviors in pullout of the headed bars. The square steel heads had gross area of 4 $A_{b}$ and thickness of $d_{b}$ The test program consisted of three pullout test groups: Simple and Edge pullout tests using plain concrete slabs, comparison of pullout performances between the standard hooks and the headed reinforcement, and pullout tests of headed reinforcement using reinforced concrete columns. Test variables included concrete strengths ( $f_{c}$' = 27.1MPa, 39.1MPa), reinforcing bar diameters (D16~D29), embedment depths (6 $d_{b}$~12 $d_{b}$), edge conditions, column reinforcement, and single-vs.-multiple bar pullout. Test results revealed that the heads effectively provided the pullout resistances of the deformed bars in tension. The load-displacement behaviors were similar between the 90-degree hooks and the headed reinforcement. When a multiple number of headed bars installed with small head-to-head spacings was pulled out, reinforcement designed to run across the concrete failure surface in a direction parallel to the headed bars helped improve the pullout performances of the headed reinforcement.t.ement.t.