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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 25, Issue 6 - Dec 2013
Volume 25, Issue 5 - Oct 2013
Volume 25, Issue 4 - Aug 2013
Volume 25, Issue 3 - Jun 2013
Volume 25, Issue 2 - Apr 2013
Volume 25, Issue 1 - Feb 2013
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Evaluation of Structural Performance of RC Beams Retrofitted Steel Fiber consequential Replacement of Recycled Coarse Aggregate and Ground Granulated Blast Furnace Slag
Ha, Gee-Joo ; Yi, Dong-Ryul ; Ha, Jae-Hoon ;
Journal of the Korea Concrete Institute, volume 25, issue 5, 2013, Pages 477~484
DOI : 10.4334/JKCI.2013.25.5.477
In this study, eleven reinforced concrete beams, ground granulated blast furnace slag, replacing recycled coarse aggregate (BRS series) and recycled coarse aggregate with steel fiber (BSRS series), and standard specimen (BSS) were constructed and tested under monotonic loading. Experimental programs were carried out to improve and evaluate the shear performance of such test specimens, such as the load-displacement, the failure mode and the maximum load carrying capacity. All the specimens were modeled in 1/2 scale-down size. Test results showed that test specimens (BSRS Series) was increased the compressive strength by 9%, the maximum load carrying capacity by 1~6% and the ductility capacity by 1.02~1.13 times in comparison with the standard specimen (BSS). And the specimens (BSRS Series) showed enough ductile behavior and stable flexural failure.
Experimental Evaluation of Bi-directionally Unbonded Prestressed Concrete Panel Impact-Resistance Behavior under Impact Loading
Yi, Na-Hyun ; Lee, Sang-Won ; Lee, Seung-Jae ; Kim, Jang-Ho Jay ;
Journal of the Korea Concrete Institute, volume 25, issue 5, 2013, Pages 485~496
DOI : 10.4334/JKCI.2013.25.5.485
In recent years, frequent terror or military attacks by explosion or impact accidents have occurred. Examplary case of these attacks were World Trade Center collapse and US Department of Defense Pentagon attack on Sept. 11 of 2001. These attacks of the civil infrastructure have induced numerous casualties and property damage, which raised public concerns and anxiety of potential terrorist attacks. However, a existing design procedure for civil infrastructures do not consider a protective design for extreme loading scenario. Also, the extreme loading researches of prestressed concrete (PSC) member, which widely used for nuclear containment vessel, gas tank, bridges, and tunnel, are insufficient due to experimental limitations of loading characteristics. To protect concrete structures against extreme loading such as explosion and impact with high strain rate, understanding of the effect, characteristic, and propagation mechanism of extreme loadings on structures is needed. Therefore, in this paper, to evaluate the impact resistance capacity and its protective performance of bi-directional unbonded prestressed concrete member, impact tests were carried out on
for reinforced concrete (RC), prestressed concrete without rebar (PS), prestressed concrete with rebar (PSR, general PSC) specimens. According to test site conditions, impact tests were performed with 14 kN impactor with drop height of 10 m, 5 m, 4 m for preliminary tests and 3.5 m for main tests. Also, in this study, the procedure, layout, and measurement system of impact tests were established. The impact resistance capacity was measured using crack patterns, damage rates, measuring value such as displacement, acceleration, and residual structural strength. The results can be used as basic research references for related research areas, which include protective design and impact numerical simulation under impact loading.
A Numerical Model to Evaluate Fire-Resistant Capacity of the Reinforced Concrete Members
Hwang, Jin-Wook ; Ha, Sang-Hee ; Lee, Yong-Hoon ; Kim, Wha-Jung ; Kwak, Hyo-Gyoung ;
Journal of the Korea Concrete Institute, volume 25, issue 5, 2013, Pages 497~508
DOI : 10.4334/JKCI.2013.25.5.497
This paper introduces a numerical model which can evaluate the fire-resistant capacity of reinforced concrete members. On the basis of the transient heat transfer considering the heat conduction, convection and radiation, time-dependent temperature distribution across a section is determined. A layered fiber section method is adopted to consider non-linear material properties depending on the temperature and varying with the position of a fiber. Furthermore, effects of non-mechanical strains of each fiber like thermal expansion, transient strain and creep strain are reflected on the non-linear structural analysis to take into account the extreme temperature variation induced by the fire. Analysis results by the numerical model are compared with experimental data from the standard fire tests to validate an exactness of the introduced numerical model. Also, time-dependent changes in the resisting capacities of reinforced concrete members exposed to fire are investigated through the analyses and, the resisting capacities evaluated are compared with those determined by the design code.
Performance Based Design of Coupling Beam Considering Probability Distribution of Flexural and Shear Strength
Kim, Yun-Gon ; Cho, Suk-Hee ;
Journal of the Korea Concrete Institute, volume 25, issue 5, 2013, Pages 509~516
DOI : 10.4334/JKCI.2013.25.5.509
In this paper, performance based design of coupling beam using non-linear static analysis is proposed considering probability distribution of flexural and shear strength in order to develop flexural hinge. This method considers post-yielding behavior of coupling beam and stress redistribution of system. It can verify the reduced effective stiffness to meet the current design requirement based on linear analysis. It also evaluates the lateral displacement under service load (un-factored wind load) properly. In addition, it can optimize the coupled shear wall system by taking stress redistribution between members into account. For a simplified 30-story building, non-linear static (push-over) analysis was performed and the structural behavior was checked at performance point and several displacement steps. Furthermore, system behavior according to the amount of reinforcement and depth of coupling beam was explored and compared each other.
Flexural & Fatigue Evaluation of Link Slab for Continuous Girder-Type Precast Modular Bridges
Joo, Bong-Chul ; Song, Jae-Joon ; Lee, Sang-Yoon ;
Journal of the Korea Concrete Institute, volume 25, issue 5, 2013, Pages 517~528
DOI : 10.4334/JKCI.2013.25.5.517
The modular technology has been already applied in automotive industry, plant and shipbuilding industry. Recently, the modular technology was applied in bridge construction. The modular bridge is different from the existing precast bridges in terms of standardized design that the detailed design of members is omitted by using the standard modules; the design of the modular bridge is completed by only assembling the standard modules without design in member level. The girder-type precast modular bridge has been developed as a simply supported bridge. The girder-type precast modular bridge could be applied to the multi-span bridges through the continuity method. The continuity of the girder-type precast modular bridge is achieved by using the link slab which is easy to construction and appropriate to the rapid construction. The link slabs have been used as the type of reinforced concrete structure in US from the 1950`s. In 2000`s, the link slab using the engineered cementitious concrete (ECC link slab) has been developed. In this study, the RC type link slab which is more reproducible and economic relative to the ECC link slab was used for the continuity of the girder-type precast modular bridges, and the construction detail of RC type link slab was modified. In addition, the modified iterative design method of RC type link slab was proposed in this study. To verify the proposed design method, the flexural tests were conducted using the RC type link slab specimens. Also, the fatigue test using the mock-up specimen was conducted with cyclic loading condition up to two million cycles.
Nonlinear Analysis of FRP Strengthened Reinforced Concrete Columns by Force-Based Finite Element Model
Cho, Chang-Geun ;
Journal of the Korea Concrete Institute, volume 25, issue 5, 2013, Pages 529~537
DOI : 10.4334/JKCI.2013.25.5.529
The aim of the current study is to develop a nonlinear isoparametric layered frame finite element (FE) analysis of FRP strengthened reinforced concrete (RC) beam or column members by a force-based FE formulation. In sections, concrete is modeled in the triaxial stress-strain relationship state and the FRP sheet is modeled as layered composite materials in two-dimension. The element stiffness matrix derived by the force-based FE has the force-interpolation functions without assuming the displacement shape functions. A lateral load test of RC column strengthened by GFRP sheets was analyzed by the developed force-based FE model. From comparative studies of the experimental and analysis results, it was shown to compare with the stiffness FE method that the force-based FE analysis could give more accurate predictions in the overall lateral load-deflection response as well as in nonlinear deformations and damages in the column plastic hinge region.
The Environmental Safety Evaluation on Heavy Metal Leaching of Deteriorated Concrete under Severe Conditions
Choi, Yun-Wang ; Oh, Sung-Rok ; Park, Man-Seok ; Kim, Sang-Chel ; Jung, Sang-Hwa ;
Journal of the Korea Concrete Institute, volume 25, issue 5, 2013, Pages 539~546
DOI : 10.4334/JKCI.2013.25.5.539
Cement industry in 1997 began to use industrial waste in cement factory for purpose of resource recycling. However recently, environmental hazard of the cement in accordance with recycling of industrial waste have been raised a problem by contamination around the cement factory and heavy metal leaching in cement. In particular, the presence of
in cement has become a critical issue, the studies for minimizing of
in cement have been performed. But, in domestic, most of the research on heavy metal leaching was carried out from the perspective of the cement. Environmental safety assessment in terms of concrete is needed because cement is used to the concrete material. Therefore, this paper was evaluated heavy metals leaching of deteriorated concrete by severe conditions. test result showed that
were not detected from all the variables.
Bond Strength of Steel Fiber Incorporated in Ultra High Performance Fiber-Reinforced Concrete
Kang, Su-Tae ;
Journal of the Korea Concrete Institute, volume 25, issue 5, 2013, Pages 547~554
DOI : 10.4334/JKCI.2013.25.5.547
This study was intended to estimate the bond strength of steel fiber in UHPFRC through pullout test. The pullout test was carried out with the double-sided pullout specimens with multiple fibers. First, the effect of fiber density on the bond strength was investigated, and the experimental result presented that the density range considered in this study was proved not to produce fiber-to-fiber interaction. The bond strength was estimated from several methods, which are based on the pullout load or energy at peak load, and the total energy absorbed until fibers are pulled out completely. the estimated bond strength obtained from the total energy was shown to be under the influence of the embedded length of fiber. the bond strengths obtained from peak load condition was 6.64 MPa in average, which had little difference compared to 6.46 MPa calculated by peak load only. Considering simplicity of test and analysis, it may be no matter to estimate the bond strength from peak load in pullout test.
Structural Behavior of Concrete Girder Continuous Bridges Strengthened with External Tendons Considering the Efficiency at Negative Moment Region
Han, Man-Yop ; Cho, Byeong-Du ; Jeon, Se-Jin ;
Journal of the Korea Concrete Institute, volume 25, issue 5, 2013, Pages 555~564
DOI : 10.4334/JKCI.2013.25.5.555
An effective method was proposed in this study which can improve the strengthening effect of continuous girder bridges by external tendons. The improvement of the proposed strengthening method in comparison with conventional methods was analyzed by applying equivalent load concept. In order to verify the strengthening effect, the enhancement of load-carrying capacity achieved by external prestressing was investigated through the test of continuous beams that were or were not strengthened by the external prestressing. The continuous beams were fabricated by making the deck slab continuous according to general construction practice of an actual concrete girder bridge. The test results showed that the deflections and strains of the strengthened beam were significantly reduced when comparing with those of the non-strengthened beam for the same level of external loads, and the stiffness of the member increased by strengthening. In particular, it was verified that the proposed method can effectively reduce the tensile stresses of the deck caused by negative moment at the intermediate supports of a continuous bridge.
Fundamental Properties and Hydration Characteristics of Mortar Based on MgO Added Industrial By-products
Hong, Sung-Gul ; Kim, Do-Young ; Lee, Dong-Sik ;
Journal of the Korea Concrete Institute, volume 25, issue 5, 2013, Pages 565~572
DOI : 10.4334/JKCI.2013.25.5.565
Hydration and physical characteristics of chemically-bonded phosphate ceramic (CBPC) binder based on dead-burned Mg-O with six different blends are investigated for efficient repair construction material by retarding set phase with
. The test specimen of the blender with silica fume shows higher compressive strength after 75 days. The CBPC with silica fume results in higher modulus of rupture that others. The test specimens of CBPC eludes lower calcium ion than that of OPC (Ordinay Portland Cement). The X-ray diffraction pattern shows that hydration results in the formation of magnesium hydroxide, M-S-H gel and
for the specimen with silica fumes. Combination with calcium for MgO is not desirable due to no formation of chemical bond between two components. Based on the experimental program, the mixture of MgO and silica fume shows efficient performance in strength and durability.
Experimental Study on the Bond Properties between GFRP Reinforcements and Steel Fiber Reinforced Concrete
Choi, Yun-Cheul ;
Journal of the Korea Concrete Institute, volume 25, issue 5, 2013, Pages 573~581
DOI : 10.4334/JKCI.2013.25.5.573
In this paper, an experimental investigation of bond properties between steel fiber reinforced concrete and glass fiber reinforced polymer reinforcements was performed. The experimental variables were diameter of reinforcements, volume fraction of steel fiber, cover thickness and compressive strength of concrete. Bond failure mainly occurred with splitting of concrete cover. Main factor for splitting of concrete is tension force occurred by the displacement difference between reinforcements and concrete. Therefore, in order to prevent the bond failure between reinforcements and concrete, capacity of tensile strength of concrete cover should be upgraded. As a results of test, volume fraction of steel fiber significantly increases the bond strength. Cover thickness changes the failure mode. Diameter of reinforcements also changes the failure mode. Generally, diameter of reinforcement also affects the bond properties but this effect is not significant as volume fraction of fiber. Increase of compressive strength increases the bond strength between concrete and reinforcement because compressive strength of concrete directly affects the tensile strength of concrete.