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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korea Concrete Institute
Journal Basic Information
Journal DOI :
Korea Concrete Institute
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Volume & Issues
Volume 12, Issue 6 - Dec 2000
Volume 12, Issue 5 - Oct 2000
Volume 12, Issue 4 - Aug 2000
Volume 12, Issue 3 - Jun 2000
Volume 12, Issue 2 - Apr 2000
Volume 12, Issue 1 - Feb 2000
Selecting the target year
Derivation of Development Length in Pretensioned Prestressed Concrete Members
Journal of the Korea Concrete Institute, volume 12, issue 6, 2000, Pages 3~11
DOI : 10.22636/JKCI.2000.12.6.3
In pretensioned concrete structures, bond between prestressing steel and concrete is an essential component to ensure the integrity of a pretensioned member. The anchorage and development of the prestressing force depend exclusively on bond. The purpose of this study is to investigate the characteristics of bond and development length between pretensioned steel and concrete. To resolve the controversy over the adequacy of the current code provision on development length of prestressing strands, a comprehensive test program has been scheduled and twenty four rectangular prestressed concrete beams have been tested to determine development length. Major test variables include diameter of strands (12.7mm, 15.2mm) and concrete covers (3cm, 4cm, 5cm). The test results indicate that the development length based on the bond stress-slip relation. The proposed model can evaluate realistically the development length of pretensioned prestressed concrete members and can be the good basis for the future basis of code equations on development length of PSC members.
A Study on the Design Parameters of the PSC I-Type Girders for Long Span Bridges
Journal of the Korea Concrete Institute, volume 12, issue 6, 2000, Pages 13~22
DOI : 10.22636/JKCI.2000.12.6.13
In order to resolve the problem of increasing traffic entailed by the economic development, road system is reorganization and new highways are built, and long span bridges over 40m are being constructed in environmental and aesthetic considerations. Most long span bridges that are currently being constructed are in general steel box girder and preflex girder bridges; however these types of breiges are less efficiency than PSC I-type girder bridges in terms of construction cost and maintenance. Therefore, in these study, structural efficiency of PSC I-type girders based on section parameters, concrete compressive strength and other design parameter is observed to develope new PSC I-type girder for long span bridges. As a results of analysis, most important design parameters that control the stress of the girder are found to be the top flange width and the height of girder. In this light, the relationship between the two variables is determined and cross-section details of the girder that most appropriates for the long span bridges are proposed. The use of high strength concrete appears to increase the general design span however the increase rate of the span from increasing concrete ultimate strength appears to be reduced depending on the span. Also, the optimal girder spacing is determined through the parameter studies of design span using the proposed girder.
Effect of Curing Temperature and Aging on the mechanical Properties of Concrete (I) -Experimental Results and Analysis-
Journal of the Korea Concrete Institute, volume 12, issue 6, 2000, Pages 23~34
DOI : 10.22636/JKCI.2000.12.6.23
This paper reports the effects of curing temperature and aging on the strength and the modulus of elasticity. In oder to determine the strength and the modulus of elasticity with curing temperature and aging, experimental and analytical methods are adopted. The tests of 480 cylinders are carried out for type I, V and V with 15 percent replacement of fly ash cement concretes, which are cured at isothermal conditions of 10, 23, 35 and 5
. and the concrete cylinders are tested at the ages of 1, 3, 7 and 28 days. According to the experimental results, the concrete subjected to high temperature at early ages attaines higher early-age compressive and splitting tensile strength but eventually attaines lower later-age compressive and splitting tensile strength. Even if modulus of elasticity has the same tendency, the variation of modulus of elasticity with curing temperature is smaller than that of compressive strength. Based on these experimental results, the relationships among compressive strength, modulus of elasticity and splitting tensile strength are proposed considering the effects of curing temperature, aging and cement type.
Effect of Curing Temperature and Aging on the Mechanical Properties of Concrete (II) -Evaluation of Prediction Models-
Journal of the Korea Concrete Institute, volume 12, issue 6, 2000, Pages 35~42
DOI : 10.22636/JKCI.2000.12.6.35
In paper I, the relationships between compressive strength and splitting tensile strength or modulus of elasticity were proposed. In this paper, new prediction model is investigated from estimating splitting tensile strength and modulus of elasticity with curing temperature and aging without compressive strength. New prediction model is based on the model which was proposed to predict compressive strength, and splitting tensile strength and modulus of elasticity calculated by this model are compared with experimental values of paper I. To evaluate in-situ applicability of the model, strength and modulus of elasticity tested with variable temperatures are estimated by the prediction model. The prediction model reasonably estimates the strength and the modulus of elasticity of type I and V cement concretes tested in paper I and experimental results with variable temperature tested in this paper.
Girder Section of Continuous Bridges Spliced by Partial Post-Tensioning
Journal of the Korea Concrete Institute, volume 12, issue 6, 2000, Pages 43~50
DOI : 10.22636/JKCI.2000.12.6.43
In this paper, a new splicing method was applied to design the girder section of bridges with the span length of 25m, 30m, 35m, 40m and 45m. A U-type precast prestressed section was also determined for each bridge. Additionally, the sectional area, beam depth and Guyon's efficiency factor of the spliced U-type sections in each span were analyzed in comparison with the present I-type PSC bridges. As a result, in spite of an increase of 31%∼50% in the sectional areas compared with the I-type precast girders, the spliced U-type the beam depth of the spliced U-type girder was designed as 2,050 mm compared with the I-type precast girder of 2,600mm in a 40m span bridge. The sectional efficiency factors of the spliced U-type sections were analyzed as 0.76∼0.99. It shows that the spliced U-type sections ar of a superior structural efficiency in contrast to the average sectional efficiency factor of 0.66 value in the I-type girders.
Charactetistics of Cement-Fly Ash Paste Containing High Early Strength Admixtures
Journal of the Korea Concrete Institute, volume 12, issue 6, 2000, Pages 51~56
DOI : 10.22636/JKCI.2000.12.6.51
Fly ash used as a cement replacement material increases the long term strength and also improves the durability of concrete and mortar. However, the use of fly ash is a little in spite of great benefit. In order to increase the consumption of fly ash, it has to be used as a cement replacement materials in the production of mortar and concrete, and the reduction of early strength development due to the use of fly ash also has to be diminished. In this study, many chemical compounds which accelerate the early strength was investigated. The
, Triethanolamine were selected and applied to the production of mortar. It was found that they enhance the early strength development of mortar(1, 3day) and decrease the amount of
, and also increase the production of ettringite. According to the results of mercury instruction test, the pores ranged from 0.01
were decreased and it was also found in the analysis of X ray and SEM that fly ash increases the amount of ettringite at early ages.
Shear Strength of Concrete Members without Transverse Steel
Journal of the Korea Concrete Institute, volume 12, issue 6, 2000, Pages 57~66
DOI : 10.22636/JKCI.2000.12.6.57
The truss analogy for the analysis of beam-columns subjected of shear and flexure is limited by the contribution of transverse and longitudinal steel and diagonal concrete compression struts. However, it should be noted that even though the behavior of reinforced concrete beam-columns after cracking can be modeled with the truss analogy, they are not perfect trusses but still structural elements with a measure of continuity provided by a diagonal tension field. The mere notion of compression field denotes that there should be some tension field coexisting perpendicularly to it. The compression field is assumed to form parallel to the crack plane that forms under combined flexure and shear. Therefore, the concrete tension field may be defined as a mechanism existing across the crack and resisting crack opening. In this paper, the effect of concrete tensile properties on the shear strength and stiffness of reinforced concrete beam-columns is discussed using the Gauss two-point truss model. The theoretical predictions are validated against the experimental observations. Although the agreement is not perfect, the comparison shows the correct trend in degradation as the inelasticity increases.
Correlation between Longitudinal Wave Velocity and Strength of Early-aged Concrete
Journal of the Korea Concrete Institute, volume 12, issue 6, 2000, Pages 67~74
DOI : 10.22636/JKCI.2000.12.6.67
The usage of nondestructive testing on early-aged concrete leads to enhacned safty and allows effective scheduling of construction, thus making it possible to maximize the time and cost efficiencies. In this study, a reliable nondestructive strength evaluation method for early-aged concrete using the longitudinal wave velocity is proposed. Compression tests were performed to examine factors influencing the velocity-strength relationship of concrete, such as water-cement (w/c) ratio, fine aggregate ratio, curing temperature, and curing condition. The test results show that a change in the w/c ratio and curing temperature has minor effect on the velocity-strength relationship/ However, curing condition significantly influences the velocity-strength relationship of early-aged concrete. Moreover, the longitudinal wave velocity increases with decreasing fine aggregate ratio. It is concluded from this study that the strength evaluation of early-age concrete can be achieved by a nonlinear equation which considers the effects of curing condition and fine aggregate ratio.
Comparison on Flexural Behaviors of Architectural Precast Prestressed Rectangular and Inverted-tee Concrete Beams
Journal of the Korea Concrete Institute, volume 12, issue 6, 2000, Pages 75~82
DOI : 10.22636/JKCI.2000.12.6.75
Flexural behaviors of two typical architectural precast beam sections ; inverted tee and rectangular - were compared and investigated. The heights of web in inverted tee beams are generally less than half of beam depth in building structures to accomodate the nib of double-tee where the total building height limited considerably. The inverted-tee beams are designed for parking live load - 500kgf/
and market - 1,200kgf/
according to the currently used typical shape in the domestic market building site in Korea. The bottom dimension and area of rectangular beams are same to those of inverted tee beams to compare the flexural behaviors of two beams. These two beams are also reinforced for similar strength. Four flexural tests are performed on two beams. Following results are obtained from the tests; 1) The rectangular beam is simpler in production, transportation, and election, and more economic than the inverted tee beam for these two beams with same dimension and similar strength. 1) The estimations of flexural strength of two beams by Strength Design Method and Strain Compatibility Method is fully complied with the result of tests. However, Strain Compatibility Method is slightly ore accurate than Strength Design Method. 2) Overall deflections of two type beam under the service loads are less than those of the allowable limit in ACI Code provision. 3) The rectangular beam is failed in large deflection (average 12.56mm large) than those of inverted tee beams. 4) The rectangular and inverted tee beams with 6m span develop initial flexural crackings under the 88% of full service loading even though they designed to satisfy the ACI tensile stress limit provisions.
Analytical Study on Discontinuous Displacement in Reinforced Concrete Column-Footing Joint under Earthquake
Journal of the Korea Concrete Institute, volume 12, issue 6, 2000, Pages 83~90
DOI : 10.22636/JKCI.2000.12.6.83
This paper presents an analytical prediction of the elastic behavior of discontinuous displacement in reinforced concrete column-footing joint under earthquake. Material nonlinearity is taken into account by comprising tensile, compressive and shear models of cracked concrete and a model of reinforcing steel. The smeared crack approach is incorporated. In boundary plane at which each member with different thickness is connected, local discontinuous deformation due to the abrupt change in their stiffness can be taken into account by introducing interface element. The proposed numerical method for hysteretic behavior of discontinuous displacement in reinforced concrete column-footing joint will be verified by comparison with reliable experimental results.
Influence of Mix Factors and Mixing Ratio of Aggregate on the Strength and Water Permeability of Porous Concrete
Journal of the Korea Concrete Institute, volume 12, issue 6, 2000, Pages 91~98
DOI : 10.22636/JKCI.2000.12.6.91
Porous concrete having continuous voids is gaining more interest as an ecological material. It has several useful functions such as water and air permeability, sound absorption, etc. Its strengths are considerably lower than those of conventional concrete due to the large and continuous voids in it. This study has been carried out to investigate the influence of mix factors and mixture proportion of aggregate on the strengths and water permeability of porous concrete. And it has been carried out to investigate the evaluation of void of porous concrete by the ultra-sonic pulse velocity. The results f this study are as follows: 1) The theoretical void ratio has greater influence than any other factor on the strengths and water permeability of porous concrete. And it is a little affected by the replacement proportion of silica-fume and mixture proportion of aggregate. 2) Because the coefficients of correlation between the void ratio and ultra-sonic pulse velocity were relatively high, it will be possible that the void ratio is predicted by the ultra-sonic pulse velocity.
Size Effect on Axial Compressive Strength of Notched Concrete Specimens
Journal of the Korea Concrete Institute, volume 12, issue 6, 2000, Pages 99~108
DOI : 10.22636/JKCI.2000.12.6.99
The size effect on axial compressive strength in notched concrete specimens was experimentally investigated. Based on the concept of the fracture mechanics and size effect law, theoretical studies for axial compressive failure of concrete were reviewed, and two failure modes of concrete specimens under compression were discussed. In this study, experiments of axial compressive failure, which is one of the two failure modes, was carried out by using cylindrical specimens. Adequate notch length was taken from the experimental result of strength variation based on the notch length. And, by taking various sizes of specimens the size effect on axial compressive strength of concrete was investigated. Also, model equations were suggested by modified size effect law (MSEL). The test results show that size effect appears conspicuously for all series of specimens. Additionally, the effect of initial notch length on axial compressive strength was also apparent.
A Study on the Influence Factors on Crack Properties of CFRD Face Slab Concrete
Journal of the Korea Concrete Institute, volume 12, issue 6, 2000, Pages 109~117
DOI : 10.22636/JKCI.2000.12.6.109
CFRD(Concrete Faced Rockfill Dam) face slab concrete has a much capability to occur crack due to drying shrinkage, plastic shrinkage and bad compaction etc. Because of these cracks of concrete induce structural problem and decrease durability of dam, it is need to reduce crack of face slab concrete. This is an experimental study to analyze the influence factors on crack properties of CFRD face slab concrete. For this purpose, various mix proportion of CFRD face slab concrete and concrete using PPF(polypropylene fiber0 and fly ash was selected. And tests for drying shrinkage, bonding strength, water permeability and plastic shrinkage were performed, and then CFRD D and PPC of those mix proportion were placed in CFRD field. According to test results, it was found that the bonding strength of C1(compact sufficiently) was higher about 10~20% than that of C2(compact insufficiently). And the engineering properties of PPC(concrete using PPF) and FAC(concrete using fly ash) were better than those of the others ; the permeability of PPC and FAC after 8 weeks curing was little lower than that of CFRD D, and plastic shrinkage crack of PPC and FAC was lower 40~60% than crack of CFRD D.
Correlation of Experimental and Analytical Inelastic Responses of A 1:12 Scale 10-Story Reinforced Concrete Frame-Wall Structure
Journal of the Korea Concrete Institute, volume 12, issue 6, 2000, Pages 119~126
DOI : 10.22636/JKCI.2000.12.6.119
Reinforced concrete structural walls are widely known to provide an efficient lateral load resistance and drift control. However, many reported researches on them are mostly limited to the RC structural walls reinforced according to seismic details. When the pushover analysis technique is used for the prediction of inelastic behavior of frame-wall structures for the seismic evaluation of existing buildings having non-seismic details, the reliability of this analysis method should be checked by the test results. The objective of this study is to verify the correlation between the experimental and analytical responses of a high-rise reinforced concrete frame-wall structure having non-seismic details by using DRAIN-2DX program and the test results performed previously. It is concluded that the behavior of the frame-wall model is mainly affected by the fixed-end rotation(uplift at base) and bending deformation of the wall and that the analysis with the LINKS model in DRAIN-2DX describes them with good reliability.