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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 16, Issue 6 - Dec 2004
Volume 16, Issue 5 - Oct 2004
Volume 16, Issue 4 - Aug 2004
Volume 16, Issue 3 - Jun 2004
Volume 16, Issue 2 - Apr 2004
Volume 16, Issue 1 - Feb 2004
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Finite Element Analysis of Transfer Length in Pretensioned Prestressed Concrete Members
Oh Byung-Hwan ; Lim Si-Nae ; Choi Young-Cheol ;
Journal of the Korea Concrete Institute, volume 16, issue 3, 2004, Pages 293~302
DOI : 10.4334/JKCI.2004.16.3.293
The transfer of prestress force in pretensioned prestressed concrete (PSC) members is of great concern because it affects directly the distribution of stress around the transfer zone. The design provision of current design code on the transfer length considers only the prestress intensity and the diameter of prestressing steels. However, other factors such as concrete compressive strength and concrete cover may affect greatly the transfer length. The purpose of the present paper is to explore the various factors that affect the transfer length in pretensioned PSC members. The bond stress-slip relation between prestressing steel and concrete was modeled first from experimental data and then this model was incorporated into the interface element. The interface element was used to perform the finite element analysis for pretensioned PSC members. The results indicate that the compressive strength and concrete cover are also very important parameters which affect the transfer length greatly. This means that the current design code, which considers only the effective prestress and diameter of prestressing steel, must be improved to take into account the other important variables of compressive strength and concrete cover. The present study allows more realistic analysis and design of pretensioned PSC members.
A Study on Strength Development and Resistance to Sulfate Attack of Mortar Incorporating Limestone Powder
Koh Kyung-Taek ; Yoo Won-Wi ; Han Sang-Mook ;
Journal of the Korea Concrete Institute, volume 16, issue 3, 2004, Pages 303~310
DOI : 10.4334/JKCI.2004.16.3.303
The purpose of this study was to investigate the effect of using method and replacement ratio of limestone powder and water-cement ratio on the compressive strength and the resistance to sulfate attack of mortar incorporating limestone powder as fundamental study to use limestone powder as an addition for concrete. As a results, The method using limestone powder as a part of cement showed decrease of the compressive strength of mortar. The strength of mortar incorporating limestone powder almost decided upon unit cement content. It was recognized that the method replacing limestone powder as a part of cement was effective to decrease the heat of hydration in concrete. The method using limestone powder as a part of fine aggregate showed the considerable increase of the strength and resistance to sulfate attack of concrete. Furthermore, it was recognized that the method using limestone powder as a part of fine aggregate were effective materials as an addition for concrete in view of the improvement of strength and resistance to sulfate attack.
Engineering Properties for Planting of Porous Concrete Block Containing Rice Straw Ash
Sung Chan-Yong ; Kim Young-Ik ;
Journal of the Korea Concrete Institute, volume 16, issue 3, 2004, Pages 311~318
DOI : 10.4334/JKCI.2004.16.3.311
This study was performed to examine engineering properties for planting of porous concrete block containing rice straw ash. Tests for void ratio, compressive and flexural strength, pH by neutralization treatment time and curing method were peformed. As results, the void ratio tends to decrease with increasing rice straw ash content. But, the compressive and flexural strength tends to increase with Increasing rice straw ash content. When the neutralization was treated at the curing age 6 days, the greatest strength was showed. The pH of porous concrete without neutralization treatment in dry and water curing are shown in 10.32
10.55 and 9.41
9.59, respectively. The pH of porous concrete by neutralization treatment in dry and water curing were shown in 9.74
10.10 and 8.13
9.32, respectively. The porous concrete block size was 23
4 cm, and species of planting were Tall fescue, Lespedeza cyrtobotrya and Lespedeza cuneata. At the 6 months after seeding, germination ratio and grown-up length of Tall fescue, Lespedeza cyrtobotrya and Lespedeza cuneata were shown in 90, 60,
, and 40
75 cm, respectively. These porous concrete block containing rice straw ash could be used for planting.
Effect of the Kinds and Replacement Ratios of Mineral Admixtures on the Development of Concrete Resistance against the Penetration of Chloride Ions
Kim Young-Jin ; Lee Sang-Soo ; Kim Dong-Seuk ; Yoo Jae-Kang ;
Journal of the Korea Concrete Institute, volume 16, issue 3, 2004, Pages 319~326
DOI : 10.4334/JKCI.2004.16.3.319
This paper investigates the effect of the concrete containing mineral admixtures(pozzolanic materials such as fly-ash, ground granulated blast-furnace slag, silica fume and meta kaolin) on the resistance properties to chloride ion invasion. The purposed testing procedure was applied to the concrete replaced mineral admixtures for 3
4 replacement ratios under water-binder ratios ranged from 0.40 to 0.55. For the electro-migration test, Tang and Nilsson's method was used to estimate the diffusion coefficient of chloride ion. As a results, the water-binder ratios, kinds of mineral admixtures and replacement ratios, water curing periods had a great effect on the diffusion coefficient of chloride ion, and the optimal replacement ratios had a limitation for each mineral admixtures. Also, the use of mineral admixtures by mass(replacement of OPC) enhance the resistance ability against chloride penetration compared with the plain concrete. The compressive strength was shown related to the diffusion coefficient of chloride ion, the compressive strength increases with the diffusion coefficient of chloride ion decreasing. Below the 50 MPa, the variation of diffusion coefficient of concrete replaced mineral admixtures was bigger than that of plain concrete.
Determination of Removal Time of the Side Form in High Strength Concrete
Han Cheon-Goo ; Han Min-Cheol ;
Journal of the Korea Concrete Institute, volume 16, issue 3, 2004, Pages 327~334
DOI : 10.4334/JKCI.2004.16.3.327
In this paper, method for the determination of removal time of the side forms in high strength concrete are discussed using the estimation model of compressive strength development, the development of bond strength and rebound number of P type Schmidt hammer in order to review the validity of existing regulation as to side form removal and offer effective quality control method. According to the results, as W/B increases by
, the setting time is shortened by about 2 hours. In the scope of the paper, required time to gain 8MPa of compressive strength is determined about 17
20 hours of age and
of maturity. Bond strength between form and concrete shows the highest value around final setting time, but decreases drastically after that. Amount of concrete sticking on the form is large before setting completed, but after that, its amount shows decline tendency. The rebound value test with P type schmidt hammer can be started faster by 2
3 hours than compressive strength test. It is also confirmed that the removal of forms is possible when the rebound value of P type schmidt hammer is more than 32. It is found from the results that existing regulation regarding removal time of the side form of high strength concrete provided in KCI needs no revision because required time to gain the strength provided in KCI has no adverse effect on strength development at early age and surface condition during stripping the side form. Effective procedure to decide the removal time of side form can be performed by applying P type Schmidt hammer.
Design of Additional Tendon Force and Evaluation of Resistant Moment for Prestressed Concrete Composite Section
Yon Jung-Heum ; Kim Do-Goon ;
Journal of the Korea Concrete Institute, volume 16, issue 3, 2004, Pages 335~344
DOI : 10.4334/JKCI.2004.16.3.335
A general composite section of precast and cast-in-place concrete with prestressed and nonprestressed reinforcements was analyzed to calculate residual stresses and loss of prestressing force caused by internal constraints of concrete long-term deformation. From the analytical results, equations to design additional prestressing force and to evaluate resistant moment of the composite section were proposed. The equations shows that the additional prestressing force can be over-estimated if the loss rate of the first prestressing force is over-estimated from the lumped sum of a design code. The analytical procedure with the proposed equations has been applied to a composite section using the AASHTO Type 5 girder. The loss rates of the additional prestressing force appling to the precast concrete girder was less than those appling to the composite girder. However, the resistant moment of the additional prestressing force on the composite girder was much larger than that on the precast concrete girder. The additional prestressing force appling to the composite section was very effective for strengthening of the prestressed concrete composite girder.
Plasticity Model Using Three Orthogonal Stress Components for Concrete in Compression
Kim Jae-Yo ; Park Hong-Gun ;
Journal of the Korea Concrete Institute, volume 16, issue 3, 2004, Pages 345~356
DOI : 10.4334/JKCI.2004.16.3.345
A plasticity model was developed to predict the behavioral characteristics of concrete in multiaxial compression. To extend the applicability of the proposed model to concrete in various stress states, a new approach for failure criteria was attempted. A stress was decomposed into one volumetric and two deviatoric components orthogonal to each other. Three failure criteria wire provided independently for each stress component. To satisfy the three failure criteria, the plasticity model using multiple failure criteria was Implemented. Each failure surface was defined by equivalent volumetric or deviatoric plastic strain. To present dilatancy due to compressive damage a non-associative flow nile was proposed. The proposed model was implemented to finite element analysis, and it was verified by comparisons with various existing test results. The comparisons show that the proposed model predicted well most of the experiments by using three independent failure criteria.
Response Analysis of RC Bridge Piers due In Multiple Earthquakes
Lee Do-Hyung ; Jeon Jong-Su ; Park Tae-Hyo ;
Journal of the Korea Concrete Institute, volume 16, issue 3, 2004, Pages 357~367
DOI : 10.4334/JKCI.2004.16.3.357
In this paper, the effect of cumulative damage for reinforced concrete bridge piers subjected to both single and multiple earthquakes is investigated. For this purpose, selected are three set of accelerograms one of which represents the real successive input ground motions, recorded at the same station with three months time interval. The analytical predictions indicate that piers are in general subjected to a large number of inelastic cycles and increased ductility demand due to multiple earthquakes, and hence more damage in terms of stiffness degradation is expected to occur. In addition, displacement ductility demand demonstrates that inelastic seismic response of piers can significantly be affected by the applied input ground motion characteristics. Also evaluated is the effect of multiple earthquakes on the response with shear. Comparative studies between the cases with and without shear indicate that stiffness degradation and hence reduction in energy dissipation capacity of piers are pronounced due to the multiple earthquakes combined with shear. It is thus concluded that the effect of multiple earthquakes should be taken into account for the stability assessment of reinforced concrete bridge piers.
Preparation and Application of CSA Expansive Additives Using Industrial Wastes
Yoon Sung-Won ; Rho Jae-Seong ;
Journal of the Korea Concrete Institute, volume 16, issue 3, 2004, Pages 369~374
DOI : 10.4334/JKCI.2004.16.3.369
Calcium sulfoalumiante(CSA) was prepared for using natural calcite(
) and industrial by-products and wastes, such as
. The mixture of raw materials was fired at 20, 400, 600,
for 1h and cooled rapidly in air. The cement replaced by
expansive additives was investigated by the measurement of the hydration products and compressive strength, setting time, expansion at wet curing condition.
was found in x-ray diffraction pattern over the temperature
. The setting time or the cement pastes added clinkers fired at different temperature was shorter than ordinary portland cement. The compressive strength was higher than the ordinary portland cement about
. The mainly hydration products were ettringite, and
. The expansion due to the formation of ettringite during hydration decreased the drying shrinkage of hardened cement rather than the ordinary portland cement.
Effect of Specimen Sizes and Shapes on Compressive Strength of Concrete
Yang Eun-Ik ; Choi Joong-Cheol ; Yi Seong-Tae ;
Journal of the Korea Concrete Institute, volume 16, issue 3, 2004, Pages 375~382
DOI : 10.4334/JKCI.2004.16.3.375
The compressive strength of concrete is used as the most basic and important material Property when reinforced concrete structures are designed. It has become a problem to use this value, however, because the control specimen sizes and shapes are different from every country. In this study, the effect of specimen sizes and shapes on compressive strength of concrete specimens was experimentally investigated based on fracture mechanics. Experiments for the Mode I failure was carried out by using cylinder, cube, and prism specimens. The test results are curve fitted using least square method(LSM) to obtain the new parameters for the modified size effect law(MSEL). The analysis results show that the effect of specimen sizes and shapes on ultimate strength is apparent. In addition, correlations between compressive strengths with size, shape, and casting direction of the specimen are investigated. For cubes and prisms the effect of placing direction on the compressive strength was investigated.
The Quality Properties of Mortar for Using Tailings from the Sangdong Tungsten One as Admixture for Concrete
Choi Yun-Wang ; Jung Moon-Young ; Jung Myung-Chae ; Koo Gi-Jung ;
Journal of the Korea Concrete Institute, volume 16, issue 3, 2004, Pages 383~390
DOI : 10.4334/JKCI.2004.16.3.383
This study has focused on the possibility for recycling tailings from the Sangdong tungsten mine as admixture for concrete. The XRD(X-ray diffraction analysis) and PSA(Particle size analysis) were performed to find mineralogical characteristics. As a result of XRD analysis, the tailings from the Sangdong tungsten fine were composed of quartz, chlorite, anorthite and cordierite etc. As a result of KSLT for cement mortar mixed with tailings from the Sangdong tungsten mine, most of heavy metals were determined as below the guide line for waste material. In addition, the setting time and compressive strength of cement mortar mixed with tailings from the Sangdong tungsten mine were investigated. It was indicated that the initial and final set were retarded according to increasing replacement of tailings from the Sangdong tungsten mine. The compressive strength of mortar was decreased with increasing replacement of failings from the Sangdong tungsten mine.
Evaluation of Crack Control and Permeability of Hydrophilic PVA fiber Reinforced Cement Composite
Won Jing-Pil ; Hwang Keum-Sik ; Park Chan-Gi ; Park Hae-Geun ;
Journal of the Korea Concrete Institute, volume 16, issue 3, 2004, Pages 391~396
DOI : 10.4334/JKCI.2004.16.3.391
Plastic shrinkage crack occurs at the exposed surfaces of freshly placed concrete due to consolidation of the concrete mass and rapid evaporation of water from the surface. This so-called shrinkage crack is a major concern for concrete, especially for flat structures such as pavements, slabs for industrial factories and retaining walls. This study has been performed to obtain the plastic shrinkage and the permeability of hydrophilic poly vinyl alcohol(PVA) fiber reinforced mortar and concrete. Test results indicated that PVA fiber reinforced cement composite showed an ability to reduce the total crack area and the maximum crack width (as compared to plain and polypropylene fiber reinforced concrete). Also, according to the permeability test result, it was found that PVA fiber reinforced cement composite was more reducing than polypropylene fiber reinforced cement composite.
Nonlinear Finite Element Analysis of Reinforced Concrete Columns
Kwon Minho ; Chang Chun Ho ;
Journal of the Korea Concrete Institute, volume 16, issue 3, 2004, Pages 397~406
DOI : 10.4334/JKCI.2004.16.3.397
A recently developed three dimensional concrete law is used for the analysis of concrete specimens and reinforced concrete columns subjected to different load patterns. The hypoelastic, orthotropic concrete constitutive model includes coupling between the deviatoric and volumetric stresses, works with both proportional and non-proportional loads and is implemented as a strain driven module. The FE implementation is based on the smeared crack approach with rotating cracks parallel to the principal strain directions. The concrete model is validated through correlated studies with: (a) experimental tests on confined concrete cylinders; (b) experimental results on three reinforced concrete columns tested at the University of California, San Diego. The correlations are overall very good, and the FE responses capture all the main phenomena observed in the experimental tests.
Compressive Strength and Chloride Permeability of High Strength Concrete according to the Variety of Mineral Admixtures
Moon Han-Young ; Kim Byoung-Kwon ;
Journal of the Korea Concrete Institute, volume 16, issue 3, 2004, Pages 407~414
DOI : 10.4334/JKCI.2004.16.3.407
The purpose of this study is to evaluate the ability to resist chloride ions penetration of the concrete structure under marine environment in south-east asia especially. In this study, high strength concrete(HSC) with various combination of ordinary portland cement(OPC), blast-furnace slag(SG) and silica fume(SF) are cured 23 and
considering the site weather, and are cured in water for 3, 7 or 56 days respectively. And to investigate the fundamental properties and the resistance of chloride penetration of various HSC, setting time, slump flow, compressive strength, void and ASTM C 1202 test were conducted. Test results show that the compressive strength of HSC is similar regardless of SG replacement ratio and total charge passed of chloride is the smallest at
replacement of SG. The compressive strength of G4FS HSC is, besides, outstandingly high at early age compare with other HSC, but the compressive strength of G4F HSC, which is vary according to curing temperature and condition, most high at the age after 7 days. Total passed charge of HSC get larger in the order G4FS
Behavior of Steel Fiber Reinforced Concrete Columns under Cyclic Loading
Chang Kug-Kwan ; Lee Hyun-Ho ;
Journal of the Korea Concrete Institute, volume 16, issue 3, 2004, Pages 415~423
DOI : 10.4334/JKCI.2004.16.3.415
To improve the brittle column behavior during seismic excitation, benefits of using steel fiber reinforced concrete in columns were investigated. For experimental study, eight specimens were used to evaluate the shear enhancement effect. The variables in this study were amount of shear reinforcement ratio (i.e., 0.26, 0.21
) and steel fiber volume fraction (i.e., 0.0, 1.0, 1.5, 2.0
). The test results indicated that the maximum enhancement of shear capacity was shown in
steel fiber content. In addition, to predict the maximum shear strength, equations of ACI 318-99, AIJ MB, NZS 3101, Hirosawa and Priestley were reviewed. From the parametric and regression study, modified Priestely equation was proposed by adding steel fiber effect.
Long-Term Performance of High Strength Concrete
Choi Yeol ; Kang Moon-Myung ;
Journal of the Korea Concrete Institute, volume 16, issue 3, 2004, Pages 425~431
DOI : 10.4334/JKCI.2004.16.3.425
This paper describes an experimental investigation of how time-dependent deformations of high strength concretes are affected by maximum size of coarse aggregate, curing time, and relatively low sustained stress level. A set of high strength concrete mixes, mainly containing two different maximum sizes of coarse aggregate, have been used to investigate drying shrinkage and creep strain of high strength concrete for 7 and 28-day moist cured cylinder specimens. Based upon one-year experimental results, drying shrinkage of high strength concrete was significantly affected by the maximum size of coarse aggregate at early age, and become gradually decreased at late age. The larger the maximum size of coarse aggregate in high strength concrete shows the lower the creep strain. The prediction equations for drying shrinkage and creep coefficient were developed on the basis of the experimental results, and compared with existing prediction models.
Sulfate Resistance of Cement Matrix Containing Limestone Powder
Moon Han-Young ; Jung Ho-Seop ; Lee Seung-Tae ; Kim Jong-Pil ;
Journal of the Korea Concrete Institute, volume 16, issue 3, 2004, Pages 433~440
DOI : 10.4334/JKCI.2004.16.3.433
In order to improve the performance of concrete, generally, modern cements often incorporate several mineral admixtures. In this study, the experimental included the flow value, air content of mortar containing limestone powder and length change and compressive strength of mortar specimen immersed in sulfate solutions. From the experimental results, the limestone powder cement matrices improved the physical properties and sulfate resistance of cement matrices at
replacement ratio of limestone powder. The
replacement ratio of limestone powder was significantly deteriorated in sodium sulfate solution. Irrespective of fineness levels of limestone powder, length change and SDF of mortar specimens with only
replacement was much superior to the other replacements.
Predictions of Seismic Behavior of Reinforced Concrete Bridge Columns
Kim Tae-Hoon ; Kim Woon-Hak ; Lee Kwang-Myong ; Shin Hyun-Mock ;
Journal of the Korea Concrete Institute, volume 16, issue 3, 2004, Pages 441~450
DOI : 10.4334/JKCI.2004.16.3.441
The objectives of this study are to investigate the seismic behavior of reinforced concrete bridge columns and to provide the data for developing improved seismic design criteria. The accuracy and objectivity of the assessment process can be enhanced by the use of sophisticated nonlinear finite element analysis program. A computer program, named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The low-cycle fatigue damage of both concrete and reinforcing bars has been also considered in order to predict a reliable seismic behavior. The proposed numerical method for the prediction of seismic behavior of reinforced concrete bridge columns is verified by comparison with the reliable experimental results.