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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korea Concrete Institute
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Journal DOI :
Korea Concrete Institute
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Volume & Issues
Volume 24, Issue 6 - Dec 2012
Volume 24, Issue 5 - Oct 2012
Volume 24, Issue 4 - Aug 2012
Volume 24, Issue 3 - Jun 2012
Volume 24, Issue 2 - Apr 2012
Volume 24, Issue 1 - Feb 2012
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Flexural Performance and Crack Damage Mitigation of Plain Concrete Beams Layered with Reinforced SHCC Materials with Polyethylene Fibers
Kim, June-Su ; Lee, Young-Oh ; Shim, Young-Yong ; Yun, Hyun-Do ;
Journal of the Korea Concrete Institute, volume 24, issue 4, 2012, Pages 361~368
DOI : 10.4334/JKCI.2012.24.4.361
Required performance for repair materials are strength, ductility, durability and bonding with the substrate concrete. Various kinds of fiber-reinforced cement composites (FRCCs) have been developed and used as repair materials. Strain-hardening cement based composites (SHCC) is one of the effective repair materials that can be used to improve crack-damage tolerance of reinforced concrete (RC) structures. SHCC is a superior FRCC that has multiple cracking characteristic and pseudo strain-hardening behavior. The expansive admixture, which can be used to reduce shrinkage in SHCC materials with less workability by controlling interfacial bonding performance between SHCC and substrate concrete. For the application of SHCC as a repair material to RC structures, this study investigates the flexural performance of expansive SHCC-layered concrete beam. Test variables include the replacement levels of expansive admixture (0 and 10%), repair thickness (30 and 40 mm), and compressive strength of SHCC (30, 70 and 100 MPa). Four point bending tests on concrete beams strengthened with SHCCs were carried out to evaluate the contribution of SHCC on the flexural capacity. The result suggested that expansive SHCC materials can be used for repairing and strengthening of concrete infrastructures.
Enhancement of Impact Resistance of Layered Steel Fiber Reinforced High Strength Concrete Beam
Yoo, Doo-Yeol ; Min, Kyung-Hwan ; Lee, Jin-Young ; Yoon, Young-Soo ;
Journal of the Korea Concrete Institute, volume 24, issue 4, 2012, Pages 369~379
DOI : 10.4334/JKCI.2012.24.4.369
The collapse of concrete structures by extreme loads such as impact, explosion, and blast from terrorist attacks causes severe property damage and human casualties. Concrete has excellent impact resistance to such extreme loads in comparison with other construction materials. Nevertheless, existing concrete structures designed without consideration of the impact or blast load with high strain rate are endangered by those unexpected extreme loads. In this study, to improve the impact resistance, the static and impact behaviors of concrete beams caste with steel fiber reinforced concrete (SFRC) with 0~1.5% (by volume) of 30 mm long hooked steel fibers were assessed. Test results indicated that the static and impact resistances, flexural strength, ductility, etc., were significantly increased when higher steel fiber volume fraction was applied. In the case of the layered concrete (LC) beams including greater steel fiber volume fraction in the tensile zone, the higher static and impact resistances were achieved than those of the normal steel fiber reinforced concrete beam with an equivalent steel fiber volume fraction. The impact test results were also compared with the analysis results obtained from the single degree of freedom (SDOF) system anaysis considering non-linear material behaviors of steel fiber reinforced concrete. The analysis results from SDOF system showed good agreement with the experimental maximum deflections.
Crack Control in Beams and One-Way Slabs
Min, Chang-Shik ;
Journal of the Korea Concrete Institute, volume 24, issue 4, 2012, Pages 381~390
DOI : 10.4334/JKCI.2012.24.4.381
The KCI Building Code (2003 and 2007) provisions to control flexural cracking in beams and one-way slabs are discussed for related researches and the development of the provisions. Based on the basic ideas over the development of current provisions, possible problems with cracking control are identified and discussed for the remedies to fix the problems. Simple and clear equations to control flexural cracking in beams and one-way slabs are presented. The presented equations would avoid any conflicts with other provisions for the spacing of reinforcement.
One-Way Shear Strength of Donut Type Biaxial Hollow Slab Considered Hollow Shapes and Materials
Chung, Joo-Hong ; Lee, Seung-Chang ; Choi, Chang-Sik ; Choi, Hyun-Ki ;
Journal of the Korea Concrete Institute, volume 24, issue 4, 2012, Pages 391~398
DOI : 10.4334/JKCI.2012.24.4.391
This paper presents the shear capacities of biaxial hollow slab with donut type hollow sphere. Recently, various types of slab systems which can reduce self-weight of slabs have been studied for increasing constructions of taller and larger building structures. A biaxial hollow slab system is widely known as one of the effective slab system, which can reduce self-weight of slab. According to previous studies, the hollow slab has low shear strength, compared to solid slab. Also, the shear capacities of biaxial hollow slab are influenced by the shapes and materials of hollow spheres. However, the current code does not provide a clear computation method for the shear strength of hollow slab. To verify the shear capacities of this hollow slab, one-way shear tests were performed. Four test specimens were used for test parameters. One was conventional RC slab and others were hollow slabs. The test parameters included two different shapes and materials of plastic balls. The shape parameters were donut and non-donut forms and the material parameters were general plastic and glass fiber plastic. The results showed that the shear strengths varied depending on hollow shapes and materials used in the slab.
A Study for Shear Deterioration of Reinforced Concrete Beam-Column Joints Failing in Shear after Flexural Yielding of Adjacent Beams
Park, Jong-Wook ; Yun, Seok-Gwang ; Kim, Byoung-Il ; Lee, Jung-Yoon ;
Journal of the Korea Concrete Institute, volume 24, issue 4, 2012, Pages 399~406
DOI : 10.4334/JKCI.2012.24.4.399
Beam-column joints are generally recognized as the critical regions in the moment resisting reinforced concrete (RC) frames subjected to both lateral and vertical loads. As a result of severe lateral load such as seismic loading, the joint region is subjected to horizontal and vertical shear forces whose magnitudes are many times higher than in column and adjacent beam. Consequently, much larger bond and shear stresses are required to sustain these magnified forces. The critical deterioration of potential shear strength in the joint area should not occur until ductile capacity of adjacent beams reach the design demand. In this study, a method was provided to predict the deformability of reinforced concrete beam-column joints failing in shear after the plastic hinges developed at both ends of the adjacent beams. In order to verify the deformability estimated by the proposed method, an experimental study consisting of three joint specimens with varying tensile reinforcement ratios was carried out. The result between the observed and predicted behavior of the joints showed reasonably good agreement.
An Experimental Study on Shear Behaviors for Reinforced Concrete Beams Embedded with GFRP Plate with Openings
Choi, Jong-Hoon ; Kim, Min-Sook ; Kim, Hee-Cheul ; Lee, Young-Hak ;
Journal of the Korea Concrete Institute, volume 24, issue 4, 2012, Pages 407~414
DOI : 10.4334/JKCI.2012.24.4.407
The purpose of this study is to experimentally investigate the shear behavior of reinforced concrete beams embedded with GFRP (glass fiber reinforced polymer) plate with openings. In this study, the parameters include the shape of reinforcement, reinforcement area, and thickness and width of reinforcements. The test was performed on 9 specimens with shear spanto-depth ratio of 2.8. When the reinforcement area was varied, the GFRP plate showed 3.6 times greater shear strength than steel stirrup. The test result showed that shear strength increased as reinforcement area increased. Also, when the shape of a parallelogram GFRP plate was used, it showed higher shear strength than that with rectangular shape. Effect of thickness and width of reinforcement showed that shear capacity increased as width increased. For a comparison study, a calculation of the shear strength of reinforced beams with GFRP plate based on the ACI 318M-08 was compared with the test results. The test results were compared with the maximum shear reinforcement areas required by ACI 318M-08, CSA-04, and EC2-02 provision.
Bond Strength of Near Surface-Mounted FRP Plate in RC Member
Seo, Soo-Yeon ;
Journal of the Korea Concrete Institute, volume 24, issue 4, 2012, Pages 415~422
DOI : 10.4334/JKCI.2012.24.4.415
This paper analyzed seventy eight previous test results to evaluate bond strength of Near Surface-Mounted (NSM) FRP and prediction formulas previously proposed by researchers. The results showed that the most reliable bond strength prediction was the one proposed by Seracino, who considered the shape coefficient (ratio of width-thickness) and stiffness of FRP. However, the equation tended to underestimate the bond strength, especially serious when FRP bond length was relatively short, because the equation did not consider the effect of bond length. Based on the analysis of previous test results, the relation between bond length and bond strength and the group effect due to close proximity of FRPs were determined. Based on the findings, the Seracino`s formula was modified and it`s applicability was evaluated. The result showed that the suggested formula can be used effectively to predict the bond strength of NSM FRP.
Ultimate Resisting Capacity of Axially Loaded Circular Concrete-Filled Steel Tube Columns
Kwak, Hyo-Gyoung ; Kwak, Ji-Hyun ;
Journal of the Korea Concrete Institute, volume 24, issue 4, 2012, Pages 423~433
DOI : 10.4334/JKCI.2012.24.4.423
The axial load on the concrete-filled steel tube (CFT) column produces confinement stress, which enhances strength of the core concrete. The amount of strength increase in concrete depends on the magnitude of produced confinement stress. From nonlinear analyses, the ultimate resisting capacity of the CFT columns subjected to axial loads was calculated. Nonlinear material properties such as Poisson`s ratio and stress-strain relation were considered in the suggested model, and the maximum confining stress was obtained by multi axial yield criteria of the steel tube. This proposed model was verified by comparing the analytical results with experimental results. Then, regression analyses were conducted to predict the maximum confining stress according to D/t ratio and material properties without rigorous structural analysis. To ensure the validity of the suggested regression formula, various empirical formulas and Eurocode4 design code were compared.
Chloride Diffusion Coefficient at Reference Time for High Performance Concrete for Bridge Pylons in Marine Environment
Yoon, Chul-Soo ; Kim, Ki-Hyun ; Yang, Woo-Yong ; Cha, Soo-Won ;
Journal of the Korea Concrete Institute, volume 24, issue 4, 2012, Pages 435~444
DOI : 10.4334/JKCI.2012.24.4.435
High performance concrete mixes are selected and corresponding test specimens are made for the study of chloride diffusion coefficient at reference time. The concrete mixes were same designs as those used in construction of bridges located in a marine environment. Mix design variables included binder type, water-to-binder ratio, mineral admixtures to total binder weight substitution ratio, fine aggregate source, chemical water reducer admixture type for high strength and high flowability, and target slump or slump flow. The test results showed that the diffusion coefficients at reference time varied significantly according to the type of mineral admixtures and their substitution ratios. A model for diffusion coefficient at reference time considering the type of mineral admixture and the substitution ratio was developed. Diffusion coefficients from the developed model were compared with those from literature review, a previous model, and additional test results. All of the comparisons verified that the developed model can reasonably predict diffusion coefficients and the application of the model to the durability design against chloride penetration is appropriate.
Evaluation of Structural Performance of Reinforced Concrete Beams Retrofitted by Embedded FRP Rod and Metal Fittings
Ha, Gee-Joo ; Shin, Jong-Hack ; Ha, Young-Joo ; Kang, Hyun-Wook ;
Journal of the Korea Concrete Institute, volume 24, issue 4, 2012, Pages 445~452
DOI : 10.4334/JKCI.2012.24.4.445
In this study, experimental research was carried out to evaluate the structural performance of the reinforced concrete beam using strengthening materials (embedded FRP rod, metal fittings) in existing reinforced concrete buildings. Seven reinforced concrete beams comprised of retrofitted embedded FRP rod (BCR series), embedded FRP rod with metal fittings (BCR-AC series), and standard specimen (BSS) were constructed and tested under monotonic loading. Design parameters of test specimens were amount of embedded FRP rod and metal fittings. The test results showed that the maximum load carrying capacity of specimens with embedded FRP rod (BCR series) and embedded FRP rod with metal fittings (BCR-AC series) increased by 21~55% and 21~63%, respectively, in comparison with the standard specimen BSS. BCR series test specimens failed by the adhesion slip and concrete cover separation. BCR-AC series test specimens failed by the adhesion slip due to the confining effect of metal fittings.
An Experimental Study on the Girder-Abutment Connection for the Steel-Concrete Composite Rigid-Frame Bridge Integrated with PS Bars
Lee, Sang-Yoon ; Ahn, Young-Soo ; Oh, Min-Ho ; Chung, Jee-Seung ; Yang, Sung-Don ;
Journal of the Korea Concrete Institute, volume 24, issue 4, 2012, Pages 453~463
DOI : 10.4334/JKCI.2012.24.4.453
Steel-concrete composite rigid-frame bridge is a type of integral bridge having advantages in bridge maintenance and structural efficiency from eliminating expansion joints and bridge supports, the main problems in bridge maintenance. The typical steel-concrete composite rigid-frame bridge has the girder-abutment connection where a part of its steel girder is embedded in abutment for integrity. However, the detail of typical girder-abutment connection is complex and increases the construction cost, especially when a part of steel girder is embedded. Recently, a new type of bridge was proposed to compensate for the disadvantages of complex details and cost increase. The compensation are expected to improve efficiency of construction by simplifying the construction detail of the girder-abutment connection. In this study, a static load test has been carried out to examine the behavior of the girder-abutment connection using real-scale specimens. The results of the test showed that the girder-abutment connection of proposed girder bridge has sufficient flexural capacity and rebars to control concrete crack should be placed on the top of abutment.
Rational Method of CLSM Mixture with Sewage Sludge Cinder
Kim, Dong-Hun ; Takashi, Horiguchi ; Lim, Nam-Gi ;
Journal of the Korea Concrete Institute, volume 24, issue 4, 2012, Pages 465~472
DOI : 10.4334/JKCI.2012.24.4.465
This research aims to find an effective mixing method for controlled low strength material (CLSM) using diverse recycled industrial byproducts. This study is a fundamental research to develop and commercialize a resource-recycling CLMS that can greatly contribute to cost reduction and environmental stress relief. In the past, few studies have been performed on CLSM in Korea. This research is expected to provide fundamental data not only for development and commercialization of the resource-recycling CLSM satisfying required material performances but also serve as a ground breaking study on utilization of recycled material in construction industry and ultimately leading to advanced resource-recycling practices at national level. From the comprehensive analysis of minimum unit quantity for maximum strength and material segregation prevention, it was found that the optimal mixing condition for mixing FSD, RSID and SD material to filler-aggregate ratio (f/a) was approximately 50.
Strengthening Effects of RC Column using Fiber Reinforced Polymer
Lee, Hyun-Ho ; Kim, Jin-Ho ; Rho, Kwamg-Geun ;
Journal of the Korea Concrete Institute, volume 24, issue 4, 2012, Pages 473~480
DOI : 10.4334/JKCI.2012.24.4.473
In order to develop an effecive seismic strengthening metghod for existing concrete structure, structural tests of aramid FRP reinforced RC columns are performed. The test variables were strengthening methods of aramid sheet and strip. The test results were evaluated by comparing strength and energy dissipation capacities of non-reinforced and reinforced specimens. The test result comparison showed that aramid sheet reinforcement on RC column was evaluated as the most efficient way to increase strength and energy dissipation capacity.
Analysis Technique for Chloride Behavior Using Apparent Diffusion Coefficient of Chloride Ion from Neural Network Algorithm
Lee, Hack-Soo ; Kwon, Seung-Jun ;
Journal of the Korea Concrete Institute, volume 24, issue 4, 2012, Pages 481~490
DOI : 10.4334/JKCI.2012.24.4.481
Evaluation of chloride penetration is very important, because induced chloride ion causes corrosion in embedded steel. Diffusion coefficient obtained from rapid chloride penetration test is currently used, however this method cannot provide a correct prediction of chloride content since it shows only ion migration velocity in electrical field. Apparent diffusion coefficient of chloride ion based on simple Fick`s Law can provide a total chloride penetration magnitude to engineers. This study proposes an analysis technique to predict chloride penetration using apparent diffusion coefficient of chloride ion from neural network (NN) algorithm and time-dependent diffusion phenomena. For this work, thirty mix proportions with the related diffusion coefficients are studied. The components of mix proportions such as w/b ratio, unit content of cement, slag, fly ash, silica fume, and fine/coarse aggregate are selected as neurons, then learning for apparent diffusion coefficient is trained. Considering time-dependent diffusion coefficient based on Fick`s Law, the technique for chloride penetration analysis is proposed. The applicability of the technique is verified through test results from short, long term submerged test, and field investigations. The proposed technique can be improved through NN learning-training based on the acquisition of various mix proportions and the related diffusion coefficients of chloride ion.
Setting Shrinkage, Coefficient of Thermal Expansion, and Elastic Modulus of UP-MMA Based Polymer Concrete
Yeon, Kyu-Seok ; Yeon, Jung-Heum ;
Journal of the Korea Concrete Institute, volume 24, issue 4, 2012, Pages 491~498
DOI : 10.4334/JKCI.2012.24.4.491
This study examines setting shrinkage, coefficient of thermal expansion, and elastic modulus of unsaturated polyester( UP)-methyl methacrylate(MMA) polymer concrete, which is generally used for repair of portland cement concrete pavement and manufacturing of precast products. In this study, a series of laboratory test were conducted with variables such as UP-MMA ratio, shrinkage reducing agent (SRA) content, and test temperature. The results showed that the setting shrinkage ranged from 29.2 to
, which was significantly affected by test temperature. Moreover, the findings revealed that the coefficient of thermal expansion, elastic modulus and ultimate strain of UP-MMA based polymer concrete ranged from 21.6 to
, 2.8 to
MPa, and 0.00381 to 0.00418, respectively. The results of this study will be used as important data for design and application of UP-MMA based polymer concrete.