Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of the Korea Concrete Institute
Journal Basic Information
Journal DOI :
Korea Concrete Institute
Editor in Chief :
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
Selecting the target year
Inelastic Time History Analysis of a 5-Story RC OMRF Considering Inelastic Shear Behavior of Beam-Column Joint
Kang, Suk-Bong ; Kim, Tae-Yong ;
Journal of the Korea Concrete Institute, volume 24, issue 6, 2012, Pages 633~641
DOI : 10.4334/JKCI.2012.24.6.633
In this study, the effects of the inelastic shear behavior of beam-column joint on the response of RC OMRF are evaluated in the inelastic time history analysis. For an example, a 5-story structure for site class SB and seismic design category C was designed in accordance with KBC2009. Bending moment-curvature relationship for beam and column was evaluated using fiber model and bending moment-rotation relationship for beam-column joint was calculated using simple and unified joint shear behavior model and moment equilibrium relationship. The hysteretic behavior was simulated using three-parameter model suggested in IDARC program. The inelastic time history analysis with PGA for return period of 2400 years showed that the model with inelastic beam-column joint yielded smaller maximum base shear force but nearly equivalent maximum roof displacement and maximum story drift as those obtained from analysis using rigid joint. The maximum story drift satisfied the criteria of KBC2009. Therefore, the inelastic shear behavior of beam-column joint could be neglected in the structural design.
Confinement Effect by Plate Type Lateral Reinforcement and Investigation of the Possibility for Use of High Strength Steel Bars in Reinforced Concrete Columns
Cho, Young-Jae ; Kim, Jin-Keun ;
Journal of the Korea Concrete Institute, volume 24, issue 6, 2012, Pages 643~650
DOI : 10.4334/JKCI.2012.24.6.643
The limitation of the yield strength in reinforced concrete columns is given for the effective use of high-strength steel bar, because very high-strength steel bar does not yield while concrete fails in compression. In order to overcome this limitation, it is required to increase peak strain of the concrete. The objective of this study is to examine the confinement effect of plate type lateral reinforcement in reinforced concrete columns. From this experimental study, the reinforced concrete columns confined by plate type carbon fiber sheets showed higher compressive strength and peak concrete strain comparing to the unconfined columns. The confinement effect is higher when cross-sectional type is a circular one than a square one. Moreover, the confinement effect was also higher for circular type confinement. Based on this study, high-strength steel bars with strength exceeding 800 MPa can be effectively used for reinforced concrete columns confined by plate type lateral reinforcements.
Evaluation of Microcracks in Thermal Damaged Concrete Using Nonlinear Ultrasonic Modulation Technique
Park, Sun-Jong ; Yim, Hong Jae ; Kwak, Hyo-Gyung ;
Journal of the Korea Concrete Institute, volume 24, issue 6, 2012, Pages 651~658
DOI : 10.4334/JKCI.2012.24.6.651
This paper concentrates on the evaluation of microcracks in thermal damaged concrete on the basis of the nonlinear ultrasonic modulation technique. Since concrete structure exposed to high temperature accompanies the development of microcracks due to the physical and chemical changes from temperature and exposed time, the adoption of nonlinear approach is required. Instead of using the conventional ultrasonic nondestructive methods which have the limitation in evaluating excessive microcracks, accordingly, a nonlinear ultrasonic modulation method which shows better sensitivity in quantifying microcracks is introduced. Upon the analysis for the modulation of ultrasonic wave and low frequency impact to measure the nonlinearity parameter, which can be used as an indicator of thermal damage, the verification processes for the introduced technique are followed: SEM investigation and permeable pore space test are performed to characterize thermally induced microcracks in concrete, and ultrasonic pulse velocity tests are performed to confirm the outstanding sensitivity of nonlinear ultrasonic modulation technique. In advance, compressive strength of thermal damaged concrete is measured to represent the effect of microcracks on performance degradation. Correlation studies between experimental data and measured data show that nonlinear ultrasonic modulation technique can effectively be used to quantify thermally induced microcracks, and to estimate the compressive strength of thermally damaged concrete.
The Influence of Specimen Volume on the Adiabatic Temperature Rise of Concrete
Bae, Jun-Young ; Cho, Sung-Hyun ; Shin, Kyung-Joon ; Kim, Yun-Yong ;
Journal of the Korea Concrete Institute, volume 24, issue 6, 2012, Pages 659~666
DOI : 10.4334/JKCI.2012.24.6.659
To secure the thermal crack resistance of mass concrete, researches and the field applications of low heat portland cement (LPC), ternary blended cement (TBC) which is produced by blending ordinary portland cement with blast furnace slag and fly ash, and early strength low heat blended cement (EBC) increased in recent years. Although the model for adiabatic temperature rise is necessary for estimating the risk of thermal cracking of concrete structures, sufficient data have not been accumulated for these mixtures. In addition, the differences in adiabatic test results have been reported for the volume of test specimens. Therefore, the present study evaluated the characteristics of adiabatic temperature rise based on the type of binder and the volume of the adiabatic test specimen. Test results indicated that the maximum temperature rise (
) and the reaction factor (r) of TBC were the lowest. Test results also showed that
and r changed with respect to the volume of test specimen.
and r obtained from 6l equipment were lower than those of 50l equipment. Therefore, corrections with respect to this phenomenon was confirmed and the corrections factors are presented.
The Effect of Anchorage with Shear Reinforcement in Flat Plate System
Choi, Chang-Sik ; Bae, Baek-Il ; Choi, Yun-Cheul ; Choi, Hyun-Ki ;
Journal of the Korea Concrete Institute, volume 24, issue 6, 2012, Pages 667~675
DOI : 10.4334/JKCI.2012.24.6.667
Flat plate are being used more in buildings requiring a high level of technical installations or in buildings needing changeable room arrangements during their life time such as office buildings. The main problem in flat plate is its weak resistance against a punching failure at its slab-column connections. Therefore, in this research, an experimental study on full-scale interior slab-column connection was performed. Three types of shear reinforcements were tested to prevent brittle punching shear failure that could lead to collapse of the structure. A series of four flat plate specimens including a specimen without shear reinforcement and three specimens with shear reinforcements were tested. The slabs were tested up to failure using monotonic vertical shear loading. The presences of the shear reinforcements substantially increased punching shear capacity and ductility of the interior slabcolumn connections. The test results showed that a slab that did not have enough bond length failed before shear reinforcement yielded due to anchorage slip. Also, FEM analyses were performed to study an effect of slab thickness and concrete compressive strength on the flat plate slab. The analytical study results were used to propose a method to calculate performance capacity of shear reinforcement in slab-column connection.
Structural Performance and Usability of Void Slab Established in T-deck Plate
Hong, Eun-Ae ; Chung, Lan ; Paik, In-Kwan ; Yun, Sung-Ho ; Cho, Seung-Ho ;
Journal of the Korea Concrete Institute, volume 24, issue 6, 2012, Pages 677~684
DOI : 10.4334/JKCI.2012.24.6.677
In recent years, extension of life span of buildings is becoming an important issue in our society. To improve the life span of buildings, rhamen structure construction and long-spanned structures are advantageous. And in order to achieve this goal, structural elements of buildings must be light and slender. As an alternative method, general porous slabs are used frequently domestically and internationally. But the study on the porous slabs using T-deck plate and assembly of light weight precast construction is insufficient at present. In this study, flexural and fatigue tests were performed on six specimens to verify structural performance and serviceability. The main parameters of the specimens were light weight and T-deck plate construction possibility as well as slab thickness. The test results indicated that the strength of porous slabs using T-deck plate and assembly of light weight were much better than general RC slabs and porous slabs without T-deck plate. And stiffness was much better than that of other tested slabs.
Evaluation on the Maximum Yield Strength of Steel Stirrups in Reinforced Concrete Beams
Lee, Jin-Eun ; Lee, Jung-Yoon ;
Journal of the Korea Concrete Institute, volume 24, issue 6, 2012, Pages 685~693
DOI : 10.4334/JKCI.2012.24.6.685
The yield strength of shear reinforcement is restricted in the present design codes. In this study, the possibility of the yield strength increase in shear reinforcement is evaluated according to ACI318-08, EC2-02 and CSA-04 by comparing the experimental and calculated results. Three cases were used to analyze the shear strength of the beam. One had no limitation in the yield strength of shear reinforcement, another had restriction on the yield strength of shear reinforcement, and the other had a restriction on the yield strength of shear reinforcement and the shear reinforcement ratio. The study results showed that the case with unlimited shear reinforcement yield strength predicted the test result better than other two cases. Even though the rebar yield strength higher than the strength required in present code was applied to existing shear design equation, the result was reasonable. Therefore, the design equation seemed to be appropriate even if the high-strength shear reinforcement is used in practice based on the existing shear design method.
Experimental Study on Fire-Resistant Characteristics of Bi-Directionally Prestressed Concrete Panel under RABT Fire Scenario
Yi, Na-Hyun ; Lee, Sang-Won ; Kim, Jang-Ho Jay ;
Journal of the Korea Concrete Institute, volume 24, issue 6, 2012, Pages 695~703
DOI : 10.4334/JKCI.2012.24.6.695
Recently, major infrastructure such as bridges, tunnels, PCCVs (Prestressed Concrete Containment Vessel), and gas tanks are Prestressed Concrete (PSC) structure types, which improve their safety by using confining effect from prestressing. Generally, concrete is known to be an outstanding fire resistant construction material. Because of this reason, researches related to extreme fire loaded PSC member behaviors are not often conducted even though PSC behavior under extreme fire loading is significantly different than that of ordinary reinforced concrete (RC) behavior. Therefore, in this study, RABT fire loading tests were performed on bi-directionally prestressed concrete panels with
dimensions. The prestressed specimens were applied with 430 kN prestressing (PS) force using unbonded PS thread bars. Also, residual strength structural tests of fire tested PSC and ordinary RC structures were performed for comparison. The study results showed that PSC behavior under fire loading is significantly different than that of RC behavior.
Seismic Performance of Hollow Rectangular Precast Segmental Piers
Lee, Jae-Hoon ; Park, Dong-Kyu ; Choi, Jin-Ho ; Shin, Sung-Jin ;
Journal of the Korea Concrete Institute, volume 24, issue 6, 2012, Pages 705~714
DOI : 10.4334/JKCI.2012.24.6.705
Precast reinforced concrete bridge columns with hollow rectangular section were tested under cyclic lateral load with constant axial force to investigate its seismic performance. After all the precast column segments were erected, longitudinal reinforcement was inserted in the sheath prefabricated in the segments, which were then mortar grouted. Main variables of the test series were column aspect ratio, longitudinal reinforcement ratio, amount of lateral reinforcement, and location of segment joints. The aspect ratios were 4.5 and 2.5, and the longitudinal steel ratios were 1.15% and 3.07%. The amount of lateral reinforcement were 95%, 55%, 50%, and 27% of the minimum amount for full ductility design requirements in the Korean Bridge Design Code. The locations of segment joints in plastic hinge region were 0.5 and 1.0 times of the section depth from the bottom column end. The test results of cracking and failure mode, axial-flexural strength, lateral load-displacement relationship, and displacement ductility are presented. Then, safety of the ductility demand based seismic design in the Korean Bridge Design Code is discussed. The column specimens showed larger ductility than expected, because buckling of longitudinal reinforcing bar was prevented due to confinement developed not only by transverse steel but also by sheath and infilling mortar.
Experimental Study on the Relationship between Time-Dependent Chloride Diffusion Coefficient and Compressive Strength
Lee, Seung-Hoon ; Kwon, Seung-Jun ;
Journal of the Korea Concrete Institute, volume 24, issue 6, 2012, Pages 715~726
DOI : 10.4334/JKCI.2012.24.6.715
Since strength and diffusion coefficient of concrete, representative concrete properties that in change with age, the time effect must be considered in the analysis of chloride penetration. In this study, an evaluation of correlation between accelerated diffusion coefficient, apparent diffusion coefficient, and compressive strength in high performance concrete with various mineral admixtures such as ground granulated blast furnace slag, fly ash, and silica fume was performed. For this work, thirty mix proportions were prepared. Accelerated diffusion coefficients at the age of 28, 91, 180, and 270 days were evaluated. For apparent diffusion coefficient, submerging test for 6 months was performed. For evaluation of compressive strength with ages, the compressive strength test was carried out at an age of 7, 28, 91, 180 days. The results of accelerated diffusion coefficient, apparent diffusion coefficient, and strength were compared, and the correlation was analyzed considering time dependency. From this study, linear relationship between accelerated diffusion and apparent diffusion coefficient were obtained regardless of concrete age. The linear relations were also observed in strength-accelerated diffusion coefficient and strength-apparent diffusion coefficient regardless of concrete age.
Investigation on Applicability of 2400 MPa Strand for Posttensioned Prestressed Concrete Girders
Park, Ho ; Cho, Jae-Yeol ; Kim, Jee-Sang ;
Journal of the Korea Concrete Institute, volume 24, issue 6, 2012, Pages 727~735
DOI : 10.4334/JKCI.2012.24.6.727
Recently, a high-strength strand of 2400 MPa was developed using domestic technologies. In 2011, KS D 7002 was revised to cover the newly developed high-strength strands to support their practical usage. Presently, however, discussions and evaluations are not sufficient on the mechanical properties of the strands and their performance in structural members. Also, there were no detailed reviews on the need to revise the current design code for practical use of the high-strength strands. In this study, flexural behavior of a member with the high-strength strands was estimated through sectional analysis and a review and comparison of the domestic and foreign design codes were conducted considering the analysis results. Also, the need for the revision of the design code was discussed. Such discussion especially focused on the estimation of the stress in strand, which related with various issues such as determination methods for yield point of strands, time-dependent loss of prestressing force, estimation of stress in strand at member failure, and net strain limit for ductile failure of member. The discussion revealed that some parts in the design code need a revision and the further studies are required.
Structural Behavior of Joints between the Hysteretic Steel Damper Connector and RC Wall Depending on Connection Details
Kang, In-Seok ; Hur, Moo-Won ;
Journal of the Korea Concrete Institute, volume 24, issue 6, 2012, Pages 737~744
DOI : 10.4334/JKCI.2012.24.6.737
Hysteretic steel damper has been applied mainly to steel buildings. However, the usage in RC buildings is rapidly increasing recently. In order to apply the steel hysteretic damper in RC buildings, supporting elements of the damper should have sufficient strength and stiffness suitable for transferring damper forces to beams and walls. But due to the inevitable damage in reinforced concrete elements due to cracking, identification of the load transfer mechanism from damper to supporting element and hysteretic characteristics of the supporting element are extremely important in evaluating the damper behavior. Experiments were carried out on connection details between RC walls and supporting elements of the steel plate typed damper such as EaSy damper. The test results showed that fracture patterns of all specimens were almost identical except in the crack number and pattern associated with shear loading condition. Among the specimens, HD-3 shoed a well distributed cracks patterns along with good performance with respect to energy dissipation capacity, stiffness deterioration, and strength degradation.
The Strength Properties of Alkali-Activated Slag Mortars by Combined Caustic Alkali with Sodium Carbonate as Activator
Kim, Tae-Wan ;
Journal of the Korea Concrete Institute, volume 24, issue 6, 2012, Pages 745~752
DOI : 10.4334/JKCI.2012.24.6.745
This paper studies the effect of the compressive strength for combined alkali-activated slag mortars. The effect of activators such as alkali type and dosage factor on the strength was investigated. The alkalis combinations made using five caustic alkalis (sodium hydroxide (NaOH, A series), calcium hydroxide (
, B series), magnesium hydroxide (
, C series), aluminum hydroxide (
, D series), and potassium hydroxide (KOH, E series)) with sodium carbonate (
) were evaluated. The mixtures were combined in different dosage at 1M, 2M, and 3M. The study results showed that the compressive strength of combined alkali-activated slag mortars tended to increase with increasing sodium carbonate. The strength of combined alkali-activated slag mortars was better than that of control cases (without sodium carbonate). The result from scanning electron microscopy (SEM) analysis confirmed that there were reaction products of calcium silicate hydrate (C-S-H) and alumina-silicate gels from combined alkali-activated slag specimens.
A Study on Improvement of Seismic Performance of High Strength Reinforced Concrete Interior Beam-Column Joints using High Ductile Fiber-Reinforced Mortar
Ha, Gee-Joo ; Hong, Kun-Ho ;
Journal of the Korea Concrete Institute, volume 24, issue 6, 2012, Pages 753~760
DOI : 10.4334/JKCI.2012.24.6.753
In this study, experimental research was carried out to evaluate and improve the constructability and seismic performance of high strength R/C interior beam-column joints regions, with or without the shear reinforcement, using high ductile fiber-reinforced mortar. Six specimens of retrofitted the beam-column joint regions using high ductile fiber-reinforced mortar are constructed and tested for their retrofit performances. Specimens designed by retrofitting the interior beam-column joint regions (IJNS series) of existing reinforced concrete building showed a stable mode of failure and an increase in load-carrying capacity due to the enhancement of crack dispersion by fiber bridging from using new high ductile materials for retrofitting. Specimens of IJNS series, designed by the retrofitting of high ductile fiber-reinforced mortar in beam-column joint regions increased its maximum load carrying capacity by 96~102.8% and its energy dissipation capacity by 0.99~1.11 folds when compared to standard specimen of SIJC with a displacement ductility of 5.
Bond Properties of GFRP Rebar with Cover Thickness and Volume Fraction of Steel Fiber
Choi, Yun-Chul ;
Journal of the Korea Concrete Institute, volume 24, issue 6, 2012, Pages 761~768
DOI : 10.4334/JKCI.2012.24.6.761
The purpose of this study is to investigate bond properties of GFRP used in SFRC (Steel fiber reinforced concrete) and normal concrete. The experimental variables were rebar diameter (D13, D16), steel fiber volume fraction (0~2%) and cover thickness (
). The experimental results showed a different failure mode depending on the cover thickness. Through the tested specimens, splitting failure occurred for the specimens with small cover thickness and pull out failure occurred in the specimens with large cover thickness. Introduction of steel fiber caused the specimens to have more ductile behavior of bond stresss-lip after peak stress, but they did not increase the bond strength significantly. These failure modes were shown in both steel reinforcement and GFRP. However, from the difference of micro structure of bond failure mechanism between steel rebar and GFRP rebar, more ductile behavior was observed in GFRP-specimens after maximum bond strength was reached.