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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 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
Selecting the target year
Effects of Corrugated GFRP Shear Connector Width and Pitch on In-plane Shear Behavior of Insulated Concrete Sandwich Wall Panels (CSWP)
Jang, Seok-Joon ; Oh, Tae-Sik ; You, Young-Chan ; Kim, Ho-Royng ; Yun, Hyun-Do ;
Journal of the Korea Concrete Institute, volume 26, issue 4, 2014, Pages 421~428
DOI : 10.4334/JKCI.2014.26.4.421
This paper describes the experimental results of insulated concrete sandwich wall panels (CSWP) with corrugated glass fiber-reinforced polymer (GFRP) shear connectors under in-plane shear loading. Corrugated GFRP shear connectors were used to improve the thermal property of insulated CSWP and to achieve composite action between the interior and exterior concrete wall panels. Test specimens were consist of three concrete panels with two insulation layers between concrete panels and middle concrete panels was loaded in the direction of gravity. To evaluate the effects of insulation types (extruded polystyrene, XPSS and expanded polystyrene, EPS), shear connector pitch (300 and 400 mm) and width (10 and 15 mm) on in-plane shear behavior of insulted CSWP, failure mode and shear flow-average relative slip relationship of specimens were investigated. Test results indicate that the bond stress between concrete panel and insulation is considerable initially. Especially in case of insulated CSWP without shear connector, initial stiffness of CSWP with XPSS is superior to that of CSWP with EPS. The shear connector's contribution to in-plane shear performance of insulated CSWP depends on the type of insulation.
Experimental Study on Combined Failure Damage of Bi-directional Prestressed Concrete Panel under Impact-Fire Loading
Yi, Na-Hyun ; Lee, Sang-Won ; Choi, Seung-Jai ; Kim, Jang-Ho Jay ;
Journal of the Korea Concrete Institute, volume 26, issue 4, 2014, Pages 429~440
DOI : 10.4334/JKCI.2014.26.4.429
Since the World Trade Center and Pentagon attacks in 2001, terror, military attack, or man-made disaster caused impact, explosion, and fire accident have frequently occured on civil infrastructures. However, structural behavior researches on major Prestressed Concrete (PSC) infrastructures such as bridges, tunnels, Prestressed Concrete Containment Vessel (PCCVs), and LNG tanks under extreme loading are significantly lacking. Especially, researches on possible secondary fire scenarios after terror, bombing, collision of vehicles and vessels on concrete structures have not been performed domestically where most of the past researches related to extreme loadings on structures focused on an independent isolated extreme loading scenario. Due to the outcry of public concerns and anxiety of potential terrorist attacks on major infrastructures and structures, a study is urgently needed at this time. Therefore, in this study, the bi-directional prestressed concrete
panels applied with 430 kN prestressing force using unbonded prestressing thread bars were experimentally evaluated under impact, fire, and impact-fire combined loadings. Due to test site restrictions, impact tests were performed with 14 kN impactor with drop heights of 10m and 3.5 m to evaluate impact resistance capacity. Also, fire and impact-fire combined loading were tested using RABT fire loading curve. The measured residual strength capacities of PSC and RC specimens applied with impact, fire, impact-fire combined loadings were compared with the residual strength capacity of undamaged PSC and RC specimens for evaluation. The study results can be used as basic research data for related research areas such as protective design and numerical simulation under extreme loading scenarios.
Compressive Behavior of Precast Concrete Column with Hollow Corresponding to Hollow Ratio
Lee, Seung-Jun ; Seo, Soo-Yeon ; Pei, Wenlong ; Kim, Kang-Su ;
Journal of the Korea Concrete Institute, volume 26, issue 4, 2014, Pages 441~448
DOI : 10.4334/JKCI.2014.26.4.441
From several researches, recently, it was found that using hollowed precast concrete (HPC) column made more compact concrete casting in joint region possible than using normal solid PC (Precast concrete) column. Therefore, the rigidity of joints can be improved like those of monolithic reinforced concrete (RC). After filling the hollow with grout concrete, however, it is expected that the HPC column behaviors like composite structure since PC element and grout concrete have different materials as well as there is a contact surface between two elements. These may affect the structural behavior and strength of the composite column. A compressive strength test was performed for the HPC column with parameter of hollow ratio for the case with and without grout in the hollow and the result is presented in this paper. The hollow ratios in the test are 35, 50 and 59% of whole section of column. Concentrated axial force was applied to top of the specimens supported as pin connection for both ends. In addition, finite element (FE) analysis was performed to simulate the failure behavior of HPC column for axial compression. As a result, it was found that the hollow ratio did not affect the initial stiffness of HPC filled with grout regardless of the strength difference of HPC and grout. However the strength was increased inversely corresponding to the hollow ratio. The structural capacity of HPC without grout closely related to the hollow size. Especially, the local collapse governs the overall failure when the thickness of HPC is too thin. Based on these effect, a suitable equation was suggested for calculation of the compressive strength of HPC column with or without grout. FE analysis considering the contact surface between HPC and grout produced a good result matched to the test result.
Effect of Curing Conditions on the Strength of Fly-Ash Based Geopolymer
Cho, Young-Keun ; Moon, Gyu-Don ; La, Jung-Min ; Jung, Sang-Hwa ;
Journal of the Korea Concrete Institute, volume 26, issue 4, 2014, Pages 449~456
DOI : 10.4334/JKCI.2014.26.4.449
Material properties of geopolymer, whose the reaction is very complicated, have been influenced by chemical compositions and particle size distributions of fly ash, concentrations and types of alkali-activators and curing conditions such as temperatures and time. In this research, experiments with several variables such as curing temperatures, preset prior to the high temperature curing and high temperatures have been conducted in order to evaluate to investigate effects on the compressive strengths of geopolymer caused by curing condition. Experiment results were evaluated with compressive strengths and micro-structures such as SEM and MIP of geopolymer pastes. As a result, as higher curing temperature or longer preset time were applied to the pastes, higher compressive strengths were observed. However, compressive strengths of geopolymer pastes declined due to increases in macropores (>50 nm) under high temperatures elapsed after 24 hours. In this sense, it can be considered that strengths and microstructures of geopolymers depends on curing temperature and time.
Influences on Concrete Quality of Residue Content Change of Chemical Admixtures
Kim, Jin-Cheol ; Yoo, Hyeok-Jin ; Kim, Hong-Sam ; Jeong, Ho-Jin ;
Journal of the Korea Concrete Institute, volume 26, issue 4, 2014, Pages 457~463
DOI : 10.4334/JKCI.2014.26.4.457
The permitted limit,
, of the change in solid contents based on ASTM C 494 as an interim standard in Korea Expressway Corporation, can not reflect the kind of chemical admixture and the characteristics of solid content so that it differed depending on the admixture types. In this study, effect of cement concrete quality was investigated by solid changes which can be used chemical admixtures acceptance criteria. As a result of an evaluation of a change in the quality of concrete due to solid content, since Ligno-sulfonate based (LG) had a low water reducing ratio, the range of the change in solid content was great while Naphthalene sulfonated based (PNS) and Poly-carboxylate based (PC) High Range Water-reducing Admixtures (HRWR) had a high water reducing ratio, the permitted limit of the difference in solid content currently used as the acceptance criterion should be readjusted. As a result, it is found that the acceptable range must be managed within 10% and 5% when the solid contents less than 25% and more than 25%, respectively.
A Comparative Study on the Environmental Impacts by Concrete Strength Using End-point LCA methodology
Kim, Sung-Hee ; Tae, Sung-Ho ; Chae, Chang-U ;
Journal of the Korea Concrete Institute, volume 26, issue 4, 2014, Pages 465~474
DOI : 10.4334/JKCI.2014.26.4.465
This is a comparative study that shows the overall environmental impacts from concrete structures when different compressive strength of concrete applied to structural systems having the same reference flow with different durability. A total of 24 MPa, 40 MPa and 60 MPa cases is analyzed to define the characteristic using end-point perspective LCA methodology including the stages of production, construction, maintenance and disposal. As results, global warming, non-renewable energy and respiratory inorganics problems are the major issues for assessing environmental impacts of concrete products.
Cracking Behavior of RC Tension Members Reinforced with Amorphous Steel Fibers
Park, Kyoung-Woo ; Lee, Jun-Seok ; Kim, Woo ; Kim, Dae-Joong ; Lee, Gi-Yeol ;
Journal of the Korea Concrete Institute, volume 26, issue 4, 2014, Pages 475~482
DOI : 10.4334/JKCI.2014.26.4.475
This paper presents the experimental results concentrically reinforced concrete tension members and compares cracking behavior of amorphous steel fiber and normal steel fiber reinforced concrete members. Two kind of steel fibers were included as a major experimental parameter together with the six cover thickness to bar diameter ratio (
). The presence of amorphous steel fibers effectively controlled the splitting cracks initation and propagation. In the amorphous steel fiber reinforced specimens, no splitting cracks were observed that becomes higher with cover thickness to bar diameter ratio is 2.0. Crack spacing of the each specimens reinforced with amorphous steel fibers and normal steel fibers becomes larger with the increase in cover thickness, and also measured maximum and average crack spacing are significantly smaller than current design code provision. Based on the measured crack spacings, a relationships for predicting the crack spacing is proposed using the measured average crack spacing in amorphous steel fiber reinforced concrete tension members.
Flexural Performance Characteristics of Amorphous Steel Fiber-Reinforced Concrete
Ku, Dong-Oh ; Kim, Seon-Du ; Kim, Hee-Seung ; Choi, Kyoung-Kyu ;
Journal of the Korea Concrete Institute, volume 26, issue 4, 2014, Pages 483~489
DOI : 10.4334/JKCI.2014.26.4.483
In this study, the flexural test of amorphous steel fiber-reinforced concrete was performed according to ASTM C 1609 to investigate its flexural performances. The amorphous steel fibers have different configurations from conventional steel fibers : thinner sections and coarser surfaces. Primary test parameters are fiber type (amorphous and conventional steel fibers), concrete compressive strength (27 and 50 MPa), and fiber volume fraction (0.25, 0.50, and 0.75%). Based on the test results, flexural strength and flexural toughness of the amorphous and conventional steel fiber-reinforced concrete were investigated. The results showed that the addition of the amorphous steel fibers into concrete could enhance both flexural strength and toughness while the addition of the conventional steel fibers into concrete was mainly effective to increase the flexural toughness.
Evaluation of Static and Fatigue Performances of Decks Reinforced with GFRP Rebar for Reinfocement Ratio
You, Young-Jun ; Park, Young-Hwan ; Choi, Ji-Hun ; Kim, Jang-Ho Jay ;
Journal of the Korea Concrete Institute, volume 26, issue 4, 2014, Pages 491~497
DOI : 10.4334/JKCI.2014.26.4.491
The corrosion of steel reinforcement in reinforced concrete bridge decks significantly affects the degradation of the capacity. Due to the advantageous characteristics such as high tensile strength and non-corrosive property, fiber reinforced polymer (FRP) has been gathering much interest from designers and engineers for possible usage as a alternative reinforcement for a steel reinforcing bar. However, its application has not been widespread, because there data for short- and long-term performance data of FRP reinforced concrete members are insufficient. In this paper, seven full-scale decks with dimensions of
were prepared and tested to failure in the laboratory. The test parameter was the bottom reinforcement ratio in transverse direction. The decks were subjected to various levels of concentrated cyclic load with a contact area of
to simulate the vehicle loading of DB-24 truck wheel loads acting on the center span of the deck. It was observed that the glass FRP (GFRP) reinforced deck on a restraint girder is strongly effected to the level of the applied load rather than the bottom reinforcement ratio. The study results showed that the maximum load less than 58% of the maximum static load can be applied to the deck to resist a fatigue load of 2 million cycles. The fatigue life of the GFRP decks from this study showed the lower and higher fatigue performance than that of ordinary steel and CFRP rebar reinforced concrete deck. respectively.
Properties of Non-Sintered Hwangtoh Mortar Using Eco-Friendly Inorganic Binding Material
Heo, Jun-Oh ; Lee, Jae-Kyu ; Hyung, Won-Gil ;
Journal of the Korea Concrete Institute, volume 26, issue 4, 2014, Pages 499~506
DOI : 10.4334/JKCI.2014.26.4.499
A number of studies on eco-friendly and healthy building materials are being conducted as modern people are becoming more conscious about health and the environment they live in. Among those materials, studies on Hwangtoh are the most prevalent but due to its strength, crack coming from drying shrinkage, and susceptibility to water, the usage of Hwangtoh is incomplete and limited to be used as a common building material. Cement concrete, considered as one of the most widely used building materials, is extensively used in construction because it is economical, easily accessible and moldable and has proper compressive strength. Due to carbon dioxide created in the process of making cement concrete, it is recognized as pollution. Accordingly, there are a lot of studies on reduction of carbon dioxide in cement concrete industry. There are increasing numbers of researches as well as developments on Hwangtoh or traditional construction materials used in South Korea to reduce the environmental problems. Therefore, this study suggests the basic features of the construction material that can replace cement concrete in the future with the non-sindtered cement mixed with non-sintering hwangtoh which is made with the furnace slag and multiple stimulants.
Assessment of Bond Characteristics between New and Old Concrete in Various Mixtures and Joint Conditions
Cho, Byeong-Du ; Kim, Sang-Hyun ; Jeon, Se-Jin ;
Journal of the Korea Concrete Institute, volume 26, issue 4, 2014, Pages 507~515
DOI : 10.4334/JKCI.2014.26.4.507
Although the construction joints of a concrete structure are properly treated with some measures, leakage has frequently occurred. A series of tests on the bond characteristics between new and old concrete were carried out in this study, assuming that the leakage at the construction joints has certain relationship with the bond of concrete. To assess the bond characteristics under various conditions, a number of specimens were made that have an interface between new and old concrete and bond strength, flexural strength and splitting tensile strength were measured. Main test variables are type and amount of mineral admixtures, treatment method of the interface and type of waterstops. In addition, the effects of placing interval between the concrete and of the age of the strength tests were investigated. The test results showed a slightly increased bond strength when applying mineral admixtures, which can be attributed to the interface filled with the calcium silicate hydrate that is formed by pozzolanic reaction. On the other hand, the bond strength was higher when the interface was treated rough and dry, and the roughness of a waterstop affected the bond capacity of the waterstop. Also, an assessment is required that considers the type of strength test because the bond strength varied according to the test methods.
Corrosion-Inhibition and Durability of Polymer-Modified Mortars Using Bisphenol A and F Type Epoxy Resin with Calumite
Kim, Joo-Young ; Kim, Wan-Ki ;
Journal of the Korea Concrete Institute, volume 26, issue 4, 2014, Pages 517~524
DOI : 10.4334/JKCI.2014.26.4.517
Nitrite-Type hydrocalumite (calumite) is a material that can adsorb chloride ions (
) that cause corrosion of reinforce bars and liberate the nitrite ions (
) that inhibit corrosion in reinforced concrete. In this study, polymer-modified mortars using two types of epoxy resin with calumite are prepared with various polymer binder-ratios of 0, 5, 10, 15, 20% and calumite contents of 0, 5%. The specimens are tested for chloride ion penetration, carbonation, drying shrinkage and corrosion inhibition. As a result, the chloride ion penetration and carbonation depth of PMM using epoxy resin somewhat increases with increasing calumite contents, but those remarkably decreases depending on the polymer-binder ratios. The 28-d drying shrinkage shows a tendency to decrease with increasing polymer-binder ratio and calumite content. Unmodified mortars with calumite content of 5% did not satisfy quality requirement by KS. However, it was satisfied with KS requirement by the modification of epoxy resin in cement mortar. On the whole, the carbonation and chloride ion penetration depth of epoxy-modified mortars with calumite is considerably improved with an increase in the polymer-binder ratio regardless of the calumite content, and is remarkably improved over unmodified mortar. And, the replacement of the portland cement with the calumite has a marked effect in the corrosion-inhibiting property of the epoxy-modified mortars.
Experiment of Shear Behavior of Reinforced Concrete Beams with High Volume Fly Ash
Yoo, Sung-Won ; Lee, Hyung-Jib ;
Journal of the Korea Concrete Institute, volume 26, issue 4, 2014, Pages 525~532
DOI : 10.4334/JKCI.2014.26.4.525
It is known that the best way to recycle fly ash is to use in concrete. It is impossible to bury in the ground this fly ash recently, so it is trying to use high volume fly ash concrete. Nevertheless, recent main research topics are focused in the part of material only, however, it is necessary to perform the research about structural shear behavior. Therefore, in this paper, 27 test members were manufactured with 3 test variables, namely fly ash replacement ratio 0, 35%, 50%, concrete compressive strength 20, 40, 60 MPa and 3 shear stirrups amounts. 27 test members were tested for shear behavior. From the test results, there were no differences between 35%, 50% high volume fly ash cement concrete and ordinary concrete without fly ash (FA=0%).
Shear Strength of Prestressed PC-CIP Composite Beams without Vertical Shear Reinforcements
Kim, Chul-Goo ; Park, Hong-Gun ; Hong, Geon-Ho ; Kang, Su-Min ; Suh, Jung-Il ;
Journal of the Korea Concrete Institute, volume 26, issue 4, 2014, Pages 533~543
DOI : 10.4334/JKCI.2014.26.4.533
Currently, composite construction of prestressed Precast Concrete (PC) and Cast-In-Place (CIP) concrete with different concrete strengths are frequently used in the modular construction. However, current design codes do not clearly define shear design methods for such composite beams. In this present study, simply supported prestressed PC-CIP composite beams without vertical shear reinforcement or only with horizontal shear reinforcement were tested to evaluate the effect of prestressing on the shear strength and the shear design method for such composite members. The test variables were the area ratio of PC and CIP concretes, prestressing force, shear span-to-depth ratio, and shear reinforcement ratio. The results showed that the shear strength was increased by the increase of prestressing force and prestressed PC area, and the decrease of shear span-to-depth ratio.
Classification Schemes of Precast Beam-Column Connections According to Contribution of Deformation Components
Choi, Hyun-Ki ; Choi, Chang-Sik ;
Journal of the Korea Concrete Institute, volume 26, issue 4, 2014, Pages 545~553
DOI : 10.4334/JKCI.2014.26.4.545
This study suggested an integrated classification method for generalized characteristics of PC beam-column connection according to connection details. Quantifying the failure mode of PC-beam column connection and characteristics of corresponding details, this study suggested to use deformation contribution of each element of beam-column assemblage. According to the expected failure mode of beam-column connection assemblage, PC beam-column connection can be classified into 'equivalent monolithic system' and 'jointed system'. In this study, four test specimens were tested for verification of detailed classification method of PC beam-column connections. Test was carried out with typical beam-column connection test method. Load was applied at the top of test specimen and end of beams were restrained by hinge. In order to verify the deformation contribution of each test specimen, 34-LVDTs were mounted on test specimen. According to test results, deformation contribution of each test specimen have different characteristics. Deformation characteristics of joint and other components which are quantified by test results, equivalent monolithic system can be classified into two categories. Strong connection have extremely small deformation contribution of joint and much larger deformation contribution was shown in flexural behavior of beam. The other type of beam-column connection is ductile connection which allows the larger deformation in joint area compared with strong connection.
Research of Residual Strain Calculation of Prestressed Concrete Beam Element
Lee, Duck-Ki ;
Journal of the Korea Concrete Institute, volume 26, issue 4, 2014, Pages 555~562
DOI : 10.4334/JKCI.2014.26.4.555
To perform performance-based seismic design of buildings, it is necessary clear goal for usage and stability after an earthquake. To clear this goal, it requires a review of the constituent material of the building and, in particular, a member used as an indicator of the residual strain is useful. There are more usage of prestressed concrete because of prestressing steel witch has characteristics of the origin-oriented. In this study, the goal is estimating of residual strain on the prestressed concrete beam member. The expression for angle of deformed prestressed concrete beam member was obtained from using of curvature on the critical section and the equivalent plastic hinge length based on 'equivalent plastic hinge length method'. Considering the balance of strength and deformation conditions, suitable analysis values were derived from 'split Element Method'. Through various parametric studies, various factors affecting the residual strain were decided. Based on the results of this study, it is expected many researches will be proceed in the future.