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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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Korea Concrete Institute
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Volume & Issues
Volume 18, Issue 6 - Dec 2006
Volume 18, Issue 5 - Oct 2006
Volume 18, Issue 4 - Aug 2006
Volume 18, Issue 3 - Jun 2006
Volume 18, Issue 2 - Apr 2006
Volume 18, Issue 1 - Feb 2006
Selecting the target year
Optimized Mix Proportioning of Steel and Hybrid Reinforced Concrete Using Harmony Search Algorithm
Lee, Chi-Hoon ; Lee, Joo-Ha ; Yoon, Young-Soo ;
Journal of the Korea Concrete Institute, volume 18, issue 2, 2006, Pages 151~159
DOI : 10.4334/JKCI.2006.18.2.151
The guide line of the SFRC mix design was not established, and the convenience of the practical application on the spot is not so good. In this paper, hence, the program which is optimized to result the mix proportion by the flexural strength and toughness, was developed to apply to SFRC on the practical spot. This program could minimize the number of trial mixes and get an economical and appropriate mixture. In addition, the theoretical background on which the program is based, will be the basis of the embodied method to mixing SFRC. Additionally, new algorithm, in this paper, was used to develop the mix proportioning program of SFRC. The new algorithm is the Harmony Search which is the heuristic method mimicking the improvisation of music players, Musical performances seek a best state determined by aesthetic estimation, as the optimization algorithms seek a best state determined by objected function value. And, it was developed the program about single fiber reinforced concrete, beside to the hybrid fiber reinforced concrete that two kinds of steel fibers, which have the different geometry, was reinforced. This will be able to keep the world trend to study, hence, offers the basis of the next research about hybrid fiber reinforced concrete.
Experimental Study on Hysteretic Behavior of 100 MPa Ultra High-Strength Concrete Tied Columns
Kim, Jong-Keun ; Shin, Sung-Woo ;
Journal of the Korea Concrete Institute, volume 18, issue 2, 2006, Pages 161~168
DOI : 10.4334/JKCI.2006.18.2.161
An experimental investigation was conducted to examine the hysteretic behaviors of ultra-high strength concrete tied columns. The purpose of this study is to investigate the safety of ultra-high strength concrete columns with 100 MPa compressive strength for the requirement of ACI provisions. Eight 1/3 scaled columns were fabricated to simulate an 1/2 story of actual structural members with the cross section
and the aspect ratio 4. The main variables are 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. Consequently, to secure the ductile behavior of 100 MPa ultra-high strength concrete columns, ACI provisions for the requirement of transverse steel may considered axial load level and the details of transverse reinforcement.
Flexural Behaviors of PSC Composite Girders in Negative Moment Regions
Kang, Byeong-Su ; Ju, Young-Tae ; Lee, Yong-Hak ;
Journal of the Korea Concrete Institute, volume 18, issue 2, 2006, Pages 169~176
DOI : 10.4334/JKCI.2006.18.2.169
Prestressed composite girder with concrete infilled steel tubes(PSC-CFT girder) is new type of bridge girder which enhances the resisting capacities due to the double composite action of PSC composite girder and concrete infilled tube. The flexural behaviors of PSC-CFT girder in the negative moment regions are investigated based on the experimental observations recently performed on two of 3.6m long specimens. The mechanical and structural roles and failure mechanism of the composite action are discussed through comparing the test results with those numerically predicted by the three methods of one and three-dimensional nonlinear finite element analysis, and section analysis method.
Nonlinear Analysis of RC Members Using Truss Model
Eom, Tae-Sung ; Park, Hong-Gun ;
Journal of the Korea Concrete Institute, volume 18, issue 2, 2006, Pages 177~188
DOI : 10.4334/JKCI.2006.18.2.177
Conventional nonlinear finite element analysis requires complicated modeling and analytical technique. Furthermore, it is difficult to interpret the analytical results presented as the stress-strain relationship. In the present study, a design-oriented analytical method using the truss model was developed. A reinforced concrete member to be analyzed was idealized by longitudinal, transverse, and diagonal line elements. Basically, each element was modeled as a composite element of concrete and re-bars. Simplified cyclic models for the concrete and re-bar elements were developed. RC beams and walls with various reinforcement details were analyzed by the proposed method. The inelastic strength, energy dissipation capacity, deformability, and failure mode predicted by the proposed method were compared with those of existing experiments. The results showed that the proposed model accurately predicted the strength and energy dissipation capacities, and to predict deformability of the members, the compression-softening model used for the concrete strut element must be improved.
Effects of Numerical Modeling on Concrete Heterogeneity
Rhee, In-Kyu ; Kim, Woo ;
Journal of the Korea Concrete Institute, volume 18, issue 2, 2006, Pages 189~198
DOI : 10.4334/JKCI.2006.18.2.189
The composition of most engineering materials is heterogeneous at some degree. It is simply a question of scale at which the level of heterogeneity becomes apparent. In the case of cementitious granular materials such as concrete the heterogeneity appears at the mesoscale where it is comprised of aggregate particles, a hardened cement paste and voids. Since it is difficult to consider each separate particle in the topological description explicitly, numerical models of the meso-structure are normally confined to two-phase matrix particle composites in which only the larger inclusions are accounted for. 2-D and 3-D concrete blocks(Representative Volume Element, RVE) are used to simulating heterogeneous concrete meso-structures in the form of aggregates in the hardened mortar with nearly zero-thickness linear or planar interfaces. The numerical sensitivity of these meso-structures are Investigated with respect to the different morphologies of heterogeneity and the different level of coupling constant among fracture mode I, II and III. In addition, a numerically homogenized concrete block in 3-D using Hashin-Shtrikman variational bounds provides an evidence of the effective cracking paths which are quite different with those of heterogenous concrete block. However, their average force-displacement relationship show a pretty close match each other.
Durability and Strength Characteristics of Concrete Using Sludge Water above Specification
Yang, Eun-Ik ; Park, Jin-Ho ; Kim, Kang-Rea ; Jo, Gyou-Jea ;
Journal of the Korea Concrete Institute, volume 18, issue 2, 2006, Pages 199~204
DOI : 10.4334/JKCI.2006.18.2.199
Recently, The sludge water of ready mixed concrete has been investigated because of environmental pollution and disposal cost. So, sludge water is partially reused as mixing water. However, if sludge water is reused too much that would influence the qualify of concrete. KS specification limits the amount of sludge content up to 3% of cement weight. In this study, the effect of ready mixed concrete sludge on the characteristics of concrete is compared to raise the reuse ratio of sludge of ready mixed concrete. According to this experiment results, as blending ratio of re-mi-con sludge increases, workability is decreases. However, the sludge of ready mixed concrete water have a positive effect on the strength development. The drying shrinkage and the resistance of freezing and thawing have a minor effect.
Evaluation on Durability of High Performance Concrete with Expansive Additive and Shrinkage Reducing Admixture
Koh, Kyung-Taek ; Kang, Su-Tae ; Park, Jung-Jun ; Ryu, Gum-Sung ;
Journal of the Korea Concrete Institute, volume 18, issue 2, 2006, Pages 205~211
DOI : 10.4334/JKCI.2006.18.2.205
The objective of this study was to evaluate the durability of low shrinkage high performance concrete(LSHPC), which was combined with expansive additives and shrinkage reducing admixtures. We tested for not only LSHPC but also high performance concrete(HPC) and normal concrete(NC) to be compared with the durability of LSHPC. HPC was made in the same water-binder ratio of LSHPC without expansive additives and shrinkage reducing admixture. As a result, it was found that LSHPC had higher compressive and tensile strength than that of HPC. LSHPC showed more excellent performance than HPC and NC in the case of resistance to chloride ion penetration and resistance to carbonation and also showed nearly 100 durability factor in the freeze-thawing test with 500 cycles. From the examination about the watertightness and the pore distribution, it was found that the durability of LSHPC was improved because its hardened cement paste is organized closer. So we can conclude that when LSHPC is applied to structures in field, it is possible to reduce the shrinkage and crack in concrete and improve the durability.
Autogenous Shrinkage of Cement Paste Considering Disjoining Pressure in Thin Adsorbed Region
Lee, Chang-Soo ; Park, Jong-Hyok ;
Journal of the Korea Concrete Institute, volume 18, issue 2, 2006, Pages 213~218
DOI : 10.4334/JKCI.2006.18.2.213
Meniscus, adsorbed layer thickness, capillary pressure and disjoining pressure was deduced in extended meniscus region in cement paste pore by hydrostatic equilibrium. From the results, the relationship between pore size and adsorbed layer thickness could be derived and adsorbed layer thickness represents
according to pore size
. Especially, disjoining pressure rapidly Increased in less than 10 nm pore size according to adsorbed layer thickness. Therefore, it is interpreted that autogenous shrinkage of cement paste is highly increases in formation of less than 10 nm pore size. Predictions of autogenous shrinkage in cement paste considering driving force for autogenous shrinkage with capillary pressure and disjoining pressure was low in comparison with experiment values between
days and high in later period. These tendency could be thought that pore damage by mercury injection in early age makes shrinkage driving force underestimate and assumption for unsaturated independent pore makes overestimate. These interactions might be needed corrections considering on hydration or pore replacement model.
Strength Properties and Durability of Polymer Concrete Using Mixed Waste Plastics
Joo, Myung-Ki ; Lee, Youn-Su ; Kim, Moon-Chan ; Kim, Youn-Hwan ;
Journal of the Korea Concrete Institute, volume 18, issue 2, 2006, Pages 219~226
DOI : 10.4334/JKCI.2006.18.2.219
The effects of binder content and PA content on the flexural, compressive and impact strengths, water absorption and frezzing and thawing of polymer concrete using mixed waste plastics are examined. As a result the flexural, compressive and impact strengths of the polymer concretes using mixed waste plastics tend to increase with increasing binder content and filler content, regardless of the PA content. The flexural, compressive and impact strengths of the polymer concretes using mixed waste plastics decrease with increasing PA content. The water absorption of the polymer concretes using mixed waste Plastics tend to decreased with increasing binder content, regardless of the PA content. The durability factor of the polymer concretes using mixed waste plastics tend to increased with increasing binder content. However, the durability factor of the polymer concretes using mixed waste plastics tend to decreased with increasing PA content.
Effect of Filter and Shrinkage Reducing Agent Influencing on Setting Shrinkage and Strength Properties of MMA-Modified Polymer Paste
Yeon, Kyu-Seok ; Beck, Jong-Man ; Jin, Xing-Qi ; Lee, Chi-Won ;
Journal of the Korea Concrete Institute, volume 18, issue 2, 2006, Pages 227~232
DOI : 10.4334/JKCI.2006.18.2.227
This article presents the results of experimental study that investigates the effect of filler and shrinkage reducing agent influencing on the strength properties of MMA-modified polymer paste that was produced to develop the surface-repair and coating materials of the concrete structures. Results show that the flexural and compressive strengths of the polymer paste increased 29 and 27%, respectively, when the aluminum hydroxide completely replaced the calcium carbonate as the filler Furthermore, when the shrinkage reducing agent was used 30%, both strengths decreased about 29% comparing to when the agent was not used. As in the cases of flexural and compressive strengths, the adhesive strength increased as the content of aluminum hydroxide as the filler increased, and it decreased as the content of shrinkage reducing agent increased. The adhesive strength with a dry concrete substrate turned out to be
higher than that with a wet concrete substrate.
Estimation of Concrete Cover Failure Time Considering the Corrosion Rate in Reinforced Concrete Structures
Jang, Bong-Seok ;
Journal of the Korea Concrete Institute, volume 18, issue 2, 2006, Pages 233~238
DOI : 10.4334/JKCI.2006.18.2.233
In lifetime estimation, the FEM analysis method is proposed for predicting corrosion failure time of concrete structures exposed to sea-water. This study shows that the corrosion rate of rebar in artificial pore solution can be transferred to the corrosion rate of rebar in concrete using the relationship between pore volume and concrete volume by Jennings` model. And this study considered the pitting corrosion effects of reinforcement bar on corrosion failure analysis, rebar size to cover depth and nonlinear crack analysis. These analysis results have good accordance with the experimental results of Williamson`s work. This methodology can be applied to lifetime prediction procedure of reinforced concrete structures and also gives more reasonable results of concrete cover failure time estimation of reinforced concrete structures exposed to sea-water.
Probability-Based Durability Analysis of Concrete Structures under Chloride Attack Environments
Kim, Jee-Sang ; Jung, Sang-Hwa ; Kim, Joo-Hyung ; Lee, Kwang-Myong ; Bae, Su-Ho ;
Journal of the Korea Concrete Institute, volume 18, issue 2, 2006, Pages 239~248
DOI : 10.4334/JKCI.2006.18.2.239
Recently, a variety of researches has been carried out to obtain a more controlled durability and long-term performance of concrete structures under chloride attack environments. In particular, new procedures for probability-based durability analysis/design have been noticed to be very valuable for the enhancement of service life of concrete structures. Although there is still a lack of relevant data, this approach has been successfully applied to some new concrete structures. In this paper, the diffusion equation based on Fick`s second law has been solved with a time dependent diffusion coefficient and the probabilistic analysis of the durability performance has been carried out by using a Monte Carlo Simulation. From the results, the influence of each parameter on the durability of concrete structures was investigated and the new procedure for durability analysis was demonstrated in terms of chloride penetration data from various concrete structures. The new procedure might be very useful in designing important concrete structures and help to predict the remaining service life of existing concrete structures under chloride attack environments.
Influence of the Type of Fine Aggregate on Drying Shrinkage and Durability for Concrete
Koh, Kyung-Taek ; Ryu, Gum-Sung ; Yoon, Gi-Won ; Han, Cheon-Goo ; Lee, Jang-Hwa ;
Journal of the Korea Concrete Institute, volume 18, issue 2, 2006, Pages 249~255
DOI : 10.4334/JKCI.2006.18.2.249
Recently, interest grew on the quality of aggregates following the diminution of primary resources from river as to grow construction demand and the low grade of nature sand like sea sand. following, need is to diversify the supply sources of fine aggregates which are excessively relying on sea sand and urgency is to find as soon as possible aggregate resources that can substitute sea sand. On the other hand, various fine aggregates we utilized to produce concrete in the domestic construction fields. However, few studies have been systematically investigated on the effects of such fine aggregates on concrete properties. Therefore, this study examined the effects of comparatively widely used fine aggregates in the domestic construction fields on the shrinkage, durability and watertightness of concrete. Results revealed that drying shrinkage increases, and durability and watertightness degrades for concrete using crushed sand than natural fine aggregates like sea sand and river sand. Especially, the use of crushed sand exhibiting bad grain shape and grade was larger adverse effect on the quality of concrete. In addition, appropriate adjustment of the grain shape and grade during the blending of crushed sand exhibiting bad grain shape and grade with natural aggregates appeared to enhance the shrinkage and durability of concrete.
A Study on Strength of Plat-Plate Wall-Column Connections
Lee, Do-Bum ; Park, Hong-Gun ; Lee, Li-Hyung ;
Journal of the Korea Concrete Institute, volume 18, issue 2, 2006, Pages 257~266
DOI : 10.4334/JKCI.2006.18.2.257
Flat-plate building systems are utilized extensively for construction of apartments, hotels and office buildings because of short construction period, low floor-to-floor height and flexibility in plan design. Recently, to increase lateral seismic resistance of flat-plate building systems, wall-columns are used frequently. Therefore, to estimate strength of flat-plate column connection accurately, the effect of column section shape on the behavior of flat-plate column connection should be considered properly, In the present study, a numerical analysis was performed for interior connections of continuous flat-plate to analyze the effect of column section shape. For the purpose, a computer program for nonlinear FE analysis was developed, and the validity was verified. Through the parametric study, the variations of shear stress distribution around the connection were investigated. According to the result of numerical analysis, as the length of the cross section of column in the direction of lateral load increases, the effective area and the maximum shear strength providing the torsional resistance decrease considerably. Therefore, these effects should be considered properly to estimate the strength of flat-plate connection accurately.
Hydration Reaction of Non-Sintering Cement Using Inorganic Industrial Waste as Activator
Mun, Kyoung-Ju ; Lee, Chol-Woong ; So, Seung-Young ; Soh, Yang-Seob ;
Journal of the Korea Concrete Institute, volume 18, issue 2, 2006, Pages 267~274
DOI : 10.4334/JKCI.2006.18.2.267
Greenhouse gas reduction will be highlighted as the most pending question in the cement industry in future because the production of Portland cement not only consumes limestone, clay, coal, and electricity, but also release waste gases such as
, and NOX, which can contribute to the greenhouse effect and acid rain. To meet the increase of cement demand and simultaneously comply with the Kyoto Protocol, cement that gives less
discharge should be urgently developed. This study aims to manufacture non-sintering cement(NSC) by adding phosphogypsum(PG) and waste lime(WL) to granulated blast furnace slag(GBFS) as sulfate and alkali activators. This study also Investigates the hydration reaction of NSC through analysis of scanning electron microscopy(SEM), X-ray diffraction(XRD), differential thermal analysis(DTA), and pH. Results obtained from analysis of the hydrate have shown that the glassy films of GBFS are destroyed by the activation of alkali and sulfate, ions eluted from the inside of GBFS react with PG and produce ettringite, and consequently the remaining component in GBFS slowly produced C-5-H(I) gel. Here, PG is considered not only to play the role of simple activator, but also to work as a binder reacting with GBFS.
Tensile Properties of Hybrid FRP Rods with Glass and Carbon Fibers
You, Yong-Jun ; Park, Ji-Sun ; Park, Young-Hwan ; Kim, Keung-Hwan ;
Journal of the Korea Concrete Institute, volume 18, issue 2, 2006, Pages 275~282
DOI : 10.4334/JKCI.2006.18.2.275
Recently, Fiber Reinforced Polymers(FRP) has been emerged as an alternative material to solve the corrosion of steel reinforcement in reinforced concrete structures. FRP exhibits higher specific strength and lower weight compared to steel reinforcement. Moreover, good resistance to corrosion of the FRP may be useful in aggressive environments causing deterioration such as chloride environment. However, causes for higher initial cost of FRP than that of steel, little information on the long-term behavior of FRP, and brittle failure make the efforts to apply FRP in civil structures slow. Glass fiber among the fibers used to manufacture FRP can be seen as the most beneficial material with regard to initial costs. But its low elastic modulus, which attains barely a quarter of steel, nay thus lead to excessive deflections when used as reinforcement for flexural members. This research was carried out on the tensile properties of hybrid rods made with glass and carbon fibers to improve those of FRP rod made with glass fiber. Parameters were resin type and the arrangement of glass and carbon fibers. The tensile properties of hybrid rods were compared with those of rods manufactured with only glass or carbon fibers. The results indicated that the tensile properties of hybrid rod were good when the carbon fiber was arranged in the core.
Study on the Shear Strengthening of Concrete Beams with Wire Rope Clamped by Bolts
Kim, Sun-Young ; Song, Jin-Gyu ; Lee, Young-Uk ; Byun, Hang-Yong ;
Journal of the Korea Concrete Institute, volume 18, issue 2, 2006, Pages 283~290
DOI : 10.4334/JKCI.2006.18.2.283
The paper describes m experimental study on the shear strengthening of concrete beams with exposed wire rope. The strengthening method is using the mechanical bolting of wire rope tensioned on the exterior of beam section. There are two shear strengthening types. The first is closed type wrapped beam section with wire rope like as closed stirrup. The second is U type tensioned at the anchor located in the side of beam section. The main parameters of specimens are strengthening spacings of wire rope with 150, 200, and 250mm for the closed and U type respectively. The shear span ratio of specimens applied by 3-point loading is 4. The results showed that the ultimate shear strength and ductility of strengthened beams increased significantly compared with non-strengthened beams. Especially, the strengthening effect of closed type was very preferable to U type. Therefore, the shear strengthening method with wire rope is very reasonable in view of repair and rehabilitation of beams.
Strain Monitoring of Strengthened RC Beams with Hybrid Fiber Reinforced Polymer(FRP) Laminates by FBG Sensor
Hong, Geon-Ho ; Shin, Yeong-Soo ; Choi, Eun-Gyu ;
Journal of the Korea Concrete Institute, volume 18, issue 2, 2006, Pages 293~298
DOI : 10.4334/JKCI.2006.18.2.293
The reinforced concrete(RC) structures strengthened with fiber reinforced plastic(FRP) has been accepted by the construction engineering community for rehabilitation. FRP composites can present many advantages like a corrosion resistance, strength-weight ratio, relatively short application time, and cost effectiveness. The beams under design load, however, are cracked and result in degrading the strength. It is difficult to recognize cracks and deflections on the surface of the concrete members retrofitted with FRP through the life cycle. For these reasons, if they result in the effects, which were below the expected strength, we must monitor the state of concrete structures all the time in order to take an appropriate measure. Fiber Bragg Grating(FBG) sensor excel as monitoring of investigating the stress state of the retrofitted beams with FRP. The main objective of this study is to measure strain by experiment and analyze the behavior of RC beams retrofitted with FRP using FBG sensor. The kinds of FRP which were used in research are carbon, glass and improved hybrid FRP(IFRP) that has capacity than any other FRP. Other variables are the length of FRP, the number of sheet.