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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 26, Issue 6 - Dec 2014
Volume 26, Issue 5 - Oct 2014
Volume 26, Issue 4 - Aug 2014
Volume 26, Issue 3 - Jun 2014
Volume 26, Issue 2 - Apr 2014
Volume 26, Issue 1 - Feb 2014
Selecting the target year
Flexural Behavior of Ultra High Performance Fiber Reinforced Concrete Segmental Box Girder
Guo, Qingyong ; Han, Sang-Mook ;
Journal of the Korea Concrete Institute, volume 26, issue 2, 2014, Pages 109~116
DOI : 10.4334/JKCI.2014.26.2.109
The flexural behavior test of UHPC segmental box girder which has 160 MPa compressive strength and 15.4 m length was carried out. The effect of steel fibers in combination with reinforcing bars on improving the ductile performance of UHPC box girder was evaluated by comparing the flexural behavior of the UHPC segmental box girders made by the two kinds of mixing portion. The test variables are volume fraction of steel fibers and the arrangement of reinforcing bars. The behavior of UHPC box girder BF2 composed of 1% volume fraction of steel fibers and longitudinal reinforcing bars in web and upper flange with stirrup showed the similar ductile behavior with the girder BF1 composed of 2% volume fraction without stirrup in elastic stress region. But BF1 had the better stiffness and showed the more ductile behavior in inelastic stress region. Segmental interfaces of UHPC box girder have not any crack and slide until the final flexural collapse load.
Properties of Alkali-Activated Cement Mortar by Curing Method
Kim, Ji-Hoon ; Lee, Jae-Kyu ; Hyung, Won-Gil ;
Journal of the Korea Concrete Institute, volume 26, issue 2, 2014, Pages 117~124
DOI : 10.4334/JKCI.2014.26.2.117
Globally, there are environmental problems due to greenhouse gas emissions.
emissions rate of the cement industry is very high, but the continued demand of cement is needed in the future. In this study, in order to reduce the environmental impact of
emissions from cement production. The experiments were carried out for the development of non-sintered cement (have not undergone firing burning) by granulated ground blast furnace slag. In order to compare the characteristics by curing, an experiment was conducted by changing the curing conditions such as atmospheric steam curing, observe the mechanical properties for the measurement of flexural compressive strength by mortar, observe the chemical properties such as acid resistance,
penetrate resistance and analyzed the mechanism of hydration by XRD, SEM experiments. From the experimental results, as compared with portland cement usually confirm the mechanical and chemical properties excellent, it is expected be possible to apply to the undersea, underwater and underground structures that require superior durability. In addition, based on the excellent compressive strength by steam curing, it is expected to be possible to utilize as a cement replacement material in the secondary product of concrete. In the future, to solve the problem through continued research, it will be expected to reduce the effect of environmental load and to be excellent economics.
Seismic Experiment of Precast Concrete Exterior Beam-Column Joint Using Bolt Type Connection and Prestressing Method
Lee, Dong-Joo ; Lee, Ju-Dong ; Oh, Tae-Soo ; Kang, Thomas H.K. ;
Journal of the Korea Concrete Institute, volume 26, issue 2, 2014, Pages 125~133
DOI : 10.4334/JKCI.2014.26.2.125
In this study, experimental research was carried out to investigate the seismic and structural performance of precast concrete exterior beam-column joints using bolt type connection and prestressing method. A total of five full-scale exterior beam-column joints were constructed and tested under reversed cyclic loading, controlled by displacement. Results of the test are as follows: Energy dissipation capacity and pinching phenomenon of PC beam-column joints showed disadvantageous behavior compared to RC beam-column joints. However, drift capacity of the PC joint was excellent. Also, yield mechanism concentrated on embedded nuts was suitable as an exterior beam-column joint of lateral load resistance frame. Additional application of prestressing method was also very effective to control excessive pinching and cracking in the joint region, and thus improved an overall seismic performance of the PC joint.
Seismic Retrofit of School Facilities Using Rapping and Attaching Composite Material
Park, Choon-Wook ; Kim, Dong-Hwi ; Kwon, Min-Ho ; Choi, Yeol ;
Journal of the Korea Concrete Institute, volume 26, issue 2, 2014, Pages 135~142
DOI : 10.4334/JKCI.2014.26.2.135
In paper after the strong earthquake of recently the Korea neighborhood, the Korean government survey show that the 86% of school buildings in Korea are in potential damage risk and only 14% of them are designed as earthquake-resistance buildings. Earthquake Reinforcing projects of school have been a leading by the ministry of education, however their reinforcing methods done by not proved a engineering by experiment which results in uneconomical and uneffective rehabilitation for the future earthquake. An experimental and analytical study have been conducted for the shear reinforcing method of RC beam by axis and horizontal axis load using attaching composite beam. Based on the previous research, in this study, design examples are given to show the performance evaluation for the column reinforcing of old school buildings using nonlinear analysis is going to be conducted and strengthening method is going to be on the market after their performance is proved by the test.
Failure Modes of RC Beams with High Strength Reinforcement
Yoon, Seok-Kwang ; Lee, Su-Chan ; Lee, Do-Hyeong ; Lee, Jung-Yoon ;
Journal of the Korea Concrete Institute, volume 26, issue 2, 2014, Pages 143~150
DOI : 10.4334/JKCI.2014.26.2.143
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.
Stud and Puzzle-Strip Shear Connector for Composite Beam of UHPC Deck and Inverted-T Steel Girder
Lee, Kyoung-Chan ; Joh, Changbin ; Choi, Eun-Suk ; Kim, Jee-Sang ;
Journal of the Korea Concrete Institute, volume 26, issue 2, 2014, Pages 151~157
DOI : 10.4334/JKCI.2014.26.2.151
Since recently developed Ultra-High-Performance-Concrete (UHPC) provides very high strength, stiffness, and durability, many studies have been made on the application of the UHPC to bridge decks. Due to high strength and stiffness of UHPC bridge deck, the structural contribution of top flange of steel girder composite to UHPC deck would be much lower than that of conventional concrete deck. At this point of view, this study proposes a inverted-T shaped steel girder composite to UHPC deck. This girder requires a new type of shear connector because conventional shear connectors are welded on top flange. This study also proposes three different types of shear connectors, and evaluate their ultimate strength via push-out static test. The first one is a stud shear connector welded directly to the web of the girder in the transverse direction. The second one is a puzzle-strip type shear connector developed by the European Commission, and the last one is the combination of the stud and the puzzle-strip shear connectors. Experimental results showed that the ultimate strength of the transverse stud was 26% larger than that given in the AASHTO LRFD Bridge Design Specifications, but a splitting crack observed in the UHPC deck was so severe that another measure needs to be developed to prevent the splitting crack. The ultimate strength of the puzzle-strip specimen was 40% larger than that evaluated by the equation of European Commission. The specimens combined with stud and puzzle-strip shear connectors provided less strength than arithmetical sum of those. Based on the experimental observations, there appears to be no advantage of combining transverse stud and puzzle-strip shear connectors.
Generalized Lateral Load-Displacement Relationship of Reinforced Concrete Shear Walls
Mun, Ju-Hyun ; Yang, Keun-Hyeok ;
Journal of the Korea Concrete Institute, volume 26, issue 2, 2014, Pages 159~169
DOI : 10.4334/JKCI.2014.26.2.159
This study generalizes the lateral load-displacement relationship of reinforced concrete shear walls from the section analysis for moment-curvature response to straightforwardly evaluate the flexural capacity and ductility of such members. Moment and curvature at different selected points including the first flexural crack, yielding of tensile reinforcing bar, maximum strength, 80% of the maximum strength at descending branch, and fracture of tensile reinforcing bar are calculated based on the strain compatibility and equilibrium of internal forces. The strain at extreme compressive fiber to determine the curvature at the descending branch is formulated as a function of reduction factor of maximum stress of concrete and volumetric index of lateral reinforcement using the stress-strain model of confined concrete proposed by Razvi and Saatcioglu. The moment prediction models are simply formulated as a function of tensile reinforcement index, vertical reinforcement index, and axial load index from an extensive parametric study. Lateral displacement is calculated by using the moment area method of idealized curvature distribution along the wall height. The generalized lateral load-displacement relationship is in good agreement with test result, even at the descending branch after ultimate strength of shear walls.
Experiment and Nonlinear Analysis of DH Beams with Steel Form
Moon, Jeong-Ho ; Oh, Young-Hun ;
Journal of the Korea Concrete Institute, volume 26, issue 2, 2014, Pages 171~179
DOI : 10.4334/JKCI.2014.26.2.171
The purpose of this study is to evaluate the structural performance of DH beams. DH beam construction method uses thin steel plates as form-works and structural elements. The prefabricated plates and rebars of DH beams were transported to a construction site and erected for casting concrete at the site. In this study, the contribution of steel plates to the flexural strength was evaluated since the plates were expected to play a role as reinforcements. Five test specimens were made for experimental and analytical studies. They consisted of two DH beams for the positive moment test and two DH beams for the negative moment test and a RC beam for the comparison purpose. Test results on DH beams were compared with design equations and the RC beam test result. It was proven that DH beams demonstrated the good flexural behavior showing sufficient strengths and deformation capacities. Flexural strengths, principal strains of concrete, and rebar stresses were evaluated through nonlinear finite element analyses for two test beams. The analyses also showed that steel plates can contribute to the enhancement of flexural strength of DH beams. Based on experimental and analytical studies, it was concluded that steel plates of DH beams can be used as good flexural reinforcements.
Analysis of Steel Reinforcement Ratio for Bent Pile Structures Considering Column-Pile Interaction
Kim, Jae-Young ; Jeong, Sang-Seom ; Kim, Jang-Ho Jay ;
Journal of the Korea Concrete Institute, volume 26, issue 2, 2014, Pages 181~188
DOI : 10.4334/JKCI.2014.26.2.181
In this study, an interactive analysis considering column-pile interaction is performed on the basis of an equivalent base spring model for supplementing virtual fixed point design of bent pile structures. Through this analytical method, the application of the minimum steel reinforcement ratio of the pile (0.4%) is analyzed by taking into account the major influencing parameters. Furthermore, the limit depth for steel reinforcement ratio is proposed through the relationships between column and pile conditions. To obtain the detailed information, it is found that an interactive analysis is intermediate in theoretical accuracy between the virtual fixed point model analysis and full-modeling analysis. Base on this study, it is also found that the maximum bending moment is located within cracking moment of the pile when material nonlinearity is considered. Therefore, the minimum steel reinforcement ratio is appropriately applicable for the optimal design of bent pile structures. Finally, the limit depth for steel reinforcement ratio (
) is proposed by considering the field measured results. It is shown that the normalized limit depth ratio for steel reinforcement ratio (
) decreases linearly as the length-diameter ratio of pile (
) increases, and then converges at a constant value.
Shear Strength of PC-CIP Composite Beams with Shear Reinforcement
Kim, Chul-Goo ; Park, Hong-Gun ; Hong, Geon-Ho ; Kang, Su-Min ;
Journal of the Korea Concrete Institute, volume 26, issue 2, 2014, Pages 189~199
DOI : 10.4334/JKCI.2014.26.2.189
Currently, in the precast concrete construction, Precast Concrete (PC) and Cast-In-Place (CIP) concrete with different concrete strengths are frequently used. However, current design codes do not specifically provide shear design methods for PC-CIP hybrid members using dual concrete strengths. In the present study, simply supported composite beams with shear reinforcement were tested. The test variables were the area ratio of the two concretes, spacing of shear reinforcement, and shear span-to-depth ratio. The shear strengths of the test specimens were evaluated by current design codes on the basis of the test results. The results showed that the shear strength of the composite beams was affected by the concrete strength of the compressive zone and also proportional to the flexural rigidity of un-cracked sections. Furthermore, the contribution of shear reinforcements varied according to the concrete strength of the compressive zone.
A Model for Lifecycle CO
Assessment of Building Structures Considering the Mixture Proportions of Concrete
Yang, Keun-Hyeok ; Seo, Eun-A ;
Journal of the Korea Concrete Institute, volume 26, issue 2, 2014, Pages 201~210
DOI : 10.4334/JKCI.2014.26.2.201
The present study proposes a phased model to assess the lifecycle
amount of concrete structures. The considered system boundary is from cradle to recycling, which includes constituent material, transportation, batching and mixing in ready-mixed concrete plant, use and demolition of structure, and crushing and recycling of demolished concrete. The
uptake of concrete by carbonation during lifetime (40 years) of a structure and the recycling life (20 years) after demolition is estimated using a simple approach generalized to predict the carbonation depth from the surfaces of concrete element and recycled aggregates. Based on the proposed phased model, a performance evaluation table is realized to straightforwardly examine the lifecycle
amount of concrete structures. The proposed model demonstrates that the contribution of ordinary portland cement (OPC) to lifecycle
emission of the concrete structure occupies approximately 85%. Furthermore, the
uptake is estimated to be approximately 15~18% of the lifecycle
emissions of concrete structures, which corresponds to be 19~22% of the emissions from OPC production. Overall, the proposed
performance table is expected to be practically useful as a guideline to determine the
emission or uptake at each phase of concrete structures.
A Study on the Flexural Minimum Reinforcement for Prevention of Brittle Failure Specified in KCI and EN Codes
Park, Sung-Jae ; Kang, Tae-Sung ; Moon, Do-Young ;
Journal of the Korea Concrete Institute, volume 26, issue 2, 2014, Pages 211~218
DOI : 10.4334/JKCI.2014.26.2.211
In the design of reinforced rectangular concrete beam structure, the minimum amount of flexural reinforcement is required to avoid brittle failure. KCI code is based on concept of ultimate strength and usually used as a model code. But bridge design code enacted by Ministry of land, transportation and maritime affairs in 2012 is based on concept of limit state and similar to Euro code EN 1992-2. This means that the minimum reinforcement presented in both design codes has different origination and safety margin. When rectangular concrete beams with minimum reinforcement are designed according to EN and KCI codes, the amount of minimum reinforcement specified in EN code is only 76% of that in KCI code. This makes the design engineers to be confused. In this study, flexural tests were conducted on nine beams with the two different minimum reinforcement specified in KCI and EN design codes. In results, the measured ratios of nominal strength to crack strength from the test were about 25% greater than those evaluated from the equations presented in KCI and EN codes. The EN beams having only 76% of the minimum reinforcement for the KCI beams were fractured by rupture of steel reinforcement but in ductile manner. It is confirmed that the minimum reinforcement concrete beams designed according to both codes have enough safety margin in flexural capacity and moreover in ductility.
Investigation on Water Purification Effect Through Long-Term Continuous Flow Test of Porous Concrete Using Effective Microorganisms
Park, Jun-Seok ; Kim, Bong-Kyun ; Kim, Woo-Suk ; Seo, Dae-Sok ; Kim, Wha-Jung ;
Journal of the Korea Concrete Institute, volume 26, issue 2, 2014, Pages 219~227
DOI : 10.4334/JKCI.2014.26.2.219
The purpose of this study is to investigate water purification properties of porous concrete by using effective microorganisms through the long-term continuous flow test. To solve the problems such as desorption of conventional microorganisms, in this study, tertiary treatment of the effective microorganisms identified by 16S rDNA sequence analysis was adopted per each step in the manufacturing process of porous concrete. And concentration for optimum continuous flow test and operation conditions through basic experiments according to retention time were investigated. Based on the experimental results, the porous concrete applying effective microorganisms showed no toxicity on the biological water quality and exhibited excellent removal efficiency than normal porous concrete. Therefore, contaminated water quality would be improved by treatment performance investigation of contaminants through long-term continuous flow test. If problems are complemented during the experiment process, it is expected to be able to reduce the non-point pollution sources flowing into river.