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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
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Analysis Evaluation of Torsional Behavior of Hybrid Truss Bridge according to Connection Systems
Choi, Ji-Hun ; Jung, Kwang-Hoe ; Kim, Tae-Kyun ; Lee, Sang-Won ; Kim, Jang-Ho Jay ;
Journal of the Korea Concrete Institute, volume 26, issue 1, 2014, Pages 3~12
DOI : 10.4334/JKCI.2014.26.1.003
Hybrid Truss Bridge (HTB) uses steel truss webs instead of concrete webs in prestressed box girder bridges, which is becoming popular due to its structural benefits such as relatively light self-weight and good aesthetics appearance. Since the core technology of this bridge is the connection system between concrete slabs and steel truss members, several connection systems were proposed and experimentally evaluated. Also, the selected joint system was applied to the real bride design and construction. The research was performed on the connection system, since it can affect the global behavior of this bridge such as flexural and fatigue behaviors as well as the local behavior around the connection region. The evaluation study showed that HTB applied to a curved bridge or an eccentrically loaded bridge had a weak torsional capacity compared to an ordinary PSC box girder bridge due to the open cross-sectional characteristic of HTB. Therefore, three types of girders with different joint system between truss web member and concrete slab were tested for their torsional capacity. In this study, the three different types of HTB girders under torsional loading were simulated using FEM analysis to investigate the torsional behavior of HTB girders more in detail. The results are discussed in detail in the paper.
Effect of Ground Granulated Blast-Furnace Slag on Life-Cycle Environmental Impact of Concrete
Yang, Keun-Hyeok ; Seo, Eun-A ; Jung, Yeon-Back ; Tae, Sung-Ho ;
Journal of the Korea Concrete Institute, volume 26, issue 1, 2014, Pages 13~21
DOI : 10.4334/JKCI.2014.26.1.013
To quantitatively evaluate the influence of ground granulated blast-furnace slag (GGBS) as a supplementary cementitious material on the life-cycle environmental impact of concrete, a comprehensive database including 3395 laboratory mixes and 1263 plant mixes was analyzed. The life-cycle assesment studied for the environmental impact of concrete can be summarized as follows: 1) the system boundary considered was from cradle to pre-construction; 2) Korea life-cycle inventories were primarily used to assess the environmental loads in each phase of materials, transportation and production of concrete; and 3) the environmental loads were quantitatively converted into environmental impact indicators through categorization, characterization, normalization and weighting process. The life-cycle environmental impacts of concrete could be classified into three categories including global warming, photochemical oxidant creation and abiotic resource depletion. Furthermore, these environmental impacts of concrete was significantly governed by the unit content of ordinary portland cement (OPC) and decreased with the increase of the replacement level of GGBS. As a result, simple equations to assess the environmental impact indicators could be formulated as a function of the unit content of binder and replacement level of GGBS.
Performance of Fresh and Hardened Ultra High Performance Concrete without Heat Treatment
Kang, Sung-Hoon ; Hong, Sung-Gul ;
Journal of the Korea Concrete Institute, volume 26, issue 1, 2014, Pages 23~34
DOI : 10.4334/JKCI.2014.26.1.023
This study investigates the relationship between the performance of fresh and hardened Ultra-High Performance Concrete (UHPC) without heat treatment. The performance of fresh UHPC is determined by the slump flow test related to the fluidity of concrete mixtures, and the air content test. The variables of these tests are the water to binder ratio, superplasticizer dosages and volume fractions of steel fiber. Generally, insufficient fluidity and excessive air contents in concrete mixtures lead to the insufficient packing density related to the performance of harden concrete. The performance of hardened UHPC is determined by the compressive and flexural tensile tests. The results of the fresh UHPC tests show that there is the linear correlation between each variable and the slump flow diameter, and that the slump flow diameter is linearly decreased as the air content ratio increase. Using these results, the formula is developed to predict the fresh performance before mixing UHPC. The results of the hardened UHPC tests show that the hardened performance is not influenced by the air content ratio in the range of 3.2 to 4.2 per cent. However, the flexural tensile strength dominantly influenced by the volume fractions of steel fiber.
Seismic Resistance of Cast-In-Place Concrete-Filled Hollow PC Columns
Lim, Woo-Young ; Park, Hong-Gun ; Oh, Jung-Keun ; Kim, Chang-Soo ;
Journal of the Korea Concrete Institute, volume 26, issue 1, 2014, Pages 35~46
DOI : 10.4334/JKCI.2014.26.1.035
Two types of cast-in-place concrete-filled hollow PC (HPC1, HPC2) columns were developed to reduce lifting load of heavy-weight PC columns and to improve the structural integrity of joints. To form the hollow PC columns, a couple of prefabricated PC panels was used for HPC1, and special hoops were used for HPC2. Lateral pressure of wet concrete on PC faces was measured while placing the concrete inside the columns. To evaluate the seismic resistance, full scale specimens of two HPC columns and a conventional RC column were tested under combined axial compression and lateral cyclic loading. The test results showed that the structural performance of the proposed HPC columns such as intial stiffness, maximum strength, and displacement ductility was comparable to that of the conventional RC column, but the energy dissipation of HPC2 slightly decreased after rebar-buckling. However, all the test specimens satisfied the energy dissipation requirement specified in ACI 374.
An Performance Evaluation of Seismic Retrofitted Column Using FRP Composite Reinforcement for Rapid Retrofitting
Kim, Jin-Sup ; Seo, Hyun-Su ; Lim, Jeong-Hee ; Kwon, Min-Ho ;
Journal of the Korea Concrete Institute, volume 26, issue 1, 2014, Pages 47~55
DOI : 10.4334/JKCI.2014.26.1.047
As increasing number of large-size earthquake around Korean peninsula, many interests have been focused to the earthquake strengthening of existing structures. The brittle fracture of Non-seismic designed columns lead to full collapse of the building. In the past, cross-sectional extension method, a steel plate reinforcing method and fiver-reinforced method are applied to Seismic Rehabilitation Technique mainly. However, the reinforcement methods have drawbacks that induce physical damage to structures, large space, long duration time. So, in this study, performance evaluation of previously developed FRP seismic reinforcement which do not induce physical damage and short duration time was enforced. The specimens were constructed with 80% downscale. FRP seismic reinforcement are manufactured of glass fiber or aluminum plate with holes and glass fiber. From the experiment results, seismic performance of specimens which reinforced with FRP seismic reinforcement were increased.
Analytical Study on Thermal Cracking Control of Mass Concrete by Vertical Pipe Cooling Method
Seo, Tae-Seok ; Cho, Yun-Gu ; Lee, Kewn-Chu ; Lim, Chang-Keun ;
Journal of the Korea Concrete Institute, volume 26, issue 1, 2014, Pages 57~62
DOI : 10.4334/JKCI.2014.26.1.057
In this study, the vertical pipe cooling method was developed to propose the pipe cooling method suited for the vertically long mass concrete structures. FEM (finite element method) analysis was carried out to investigate the validity of the vertical pipe cooling method, and the temperature, the behavior of tensile stress of concrete and the crack index were investigated. In result, it was confirmed that the vertical pipe cooling method was effective in the thermal cracking control of mass concrete member.
Experimental Study on Improving Compressive Strength of MWCNT Reinforced Cementitious Composites
Kang, Su-Tae ; Park, Soon-Hong ;
Journal of the Korea Concrete Institute, volume 26, issue 1, 2014, Pages 63~70
DOI : 10.4334/JKCI.2014.26.1.063
This experimental study was intended to improve the compressive strength of multi-walled CNT reinforced cementitious composites with efficiency. The variables considered are the degree of sonication, the amount of surfactant, the replacement ratio of silica fume, etc. Optical microscope informed that fiber dispersion of CNT was improved with the increase of sonication time, and the compressive strength was proved to be enhanced as the degree of sonication increased. When superplasticizer as a surfactant had SP/CNT ratio of 4~6, the best improvement in strength was obtained. Silica fume was shown to produce the highest compressive strength at 10% replacement. Microstructure of CNT composites was also analyzed; XRD and SEM results indicated that CNT addition hardly changed hydration products and microstructure, and MIP analysis found the reduction of total porosity as well as the increase of nano-pores with the size of tens of nm instead of the decrease of pore distribution in the region of around 10
and 100 nm. The results of microstructure analysis explains that the strength improvement is closely related to physical contribution rather than chemical influence by adding CNT.
Influence of Temperature on Chloride Ion Diffusion of Concrete
So, Hyoung-Seok ; Choi, Seung-Hoon ; Seo, Chung-Seok ; Seo, Ki-Seog ; So, Seung-Young ;
Journal of the Korea Concrete Institute, volume 26, issue 1, 2014, Pages 71~78
DOI : 10.4334/JKCI.2014.26.1.071
The long term integrity of concrete cask is very important for spent nuclear fuel dry storage system. However, there are serious concerns about early deterioration of concrete cask from creaking and corrosion of reinforcing steel by chloride ion because the cask is usually located in seaside, expecially by combined deterioration such as chloride ion and heat, carbonation. This study is to investigate the relation between temperature and chloride ion diffusion of concrete. Immersion tests using 3.5% NaCl solution that were controlled in four level of temperature, i.e. 20, 40, 65, and
, were conducted for four months. The chloride ion diffusion coefficient of concrete was predicted based on the results of profiles of Cl- ion concentration with the depth direction of concrete specimens using the method of potentiometric titration by
. Test results indicate that the diffusion coefficient of chloride ion increases remarkably with increasing temperature, and there was a linear relation between the natural logarithm values of the diffusion coefficients and the reciprocal of the temperature from the Arrhenius plots. Activation energy of concrete in this study was about 46.6 (W/C = 40%), 41.7 (W/C = 50%), 30.7 (W/C = 60%) kJ/mol under a temperature of up to
, and concrete with lower water-cement ratio has a tendency towards having higher temperature dependency.
Analysis on the Interfacial Bond-Slip Relationship between ear Surface-Mounted FRP Plate and Concrete
Seo, Soo-Yeon ;
Journal of the Korea Concrete Institute, volume 26, issue 1, 2014, Pages 79~86
DOI : 10.4334/JKCI.2014.26.1.079
In this paper, a stress transfer mechanism between near surface-mounted (NSM) fiber reinforced polymer (FRP) plate and concrete was investigated and a reliable analytical procedure for it was presented by using bilinear bond-slip model simulating the bond behavior of NSM FRP plate. As a result, critical values in the bi-linear model such as maximum shear strength, slip at that time and failure slip at the initiation of softening de-bonding were suggested for being used in the differential equation considering he interfacial characteristic between NSM FRP and concrete. Also, it was found that the bond-slip behavior could be suitably redicted by using the proposed procedure even in the case of various bond lengths from the comparison with bond test result.
Characteristics of Structural Behavior of Steel Fiber Reinforced Ultra High Performance Concrete Beams Subjected to Torsion
Yang, In-Hwan ; Joh, Changbin ; Lee, Jung-Woo ; Kim, Byung-Suk ;
Journal of the Korea Concrete Institute, volume 26, issue 1, 2014, Pages 87~95
DOI : 10.4334/JKCI.2014.26.1.087
Experimental investigation on the structural behavior of steel fiber-reinforced ultra high performance concrete (UHPC) beams subjected to torsion are presented. Six tests carried out on square beams under torsional moment are presented. The experimental parameters were the volume fraction of the fibers and closed-stirrup ratio. The volume fraction of the fibers was 1.0% and 2.0%. The closed-stirrup ratio was 0, 0.35%, and 0.70%. The test results indicated that ultimate torsional strength increased with increasing fiber volume, and that ultimate torsional strength also increased with increasing the closed-stirrup ratio. In addition, predictive equations for evaluating the ultimate torsional strength of UHPC beams were proposed. The comparison between computed values and the experimentally observed values was shown to validate the proposed analytical equations. It was found that predictions by using proposed equation provides good agreement with test results of UHPC beams.