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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 27, Issue 6 - Dec 2015
Volume 27, Issue 5 - Oct 2015
Volume 27, Issue 4 - Aug 2015
Volume 27, Issue 3 - Jun 2015
Volume 27, Issue 2 - Apr 2015
Volume 27, Issue 1 - Feb 2015
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The Experimental Study of Full-scale Optimized Composite Beam (OCB) Reinforced with Open Strands
Lee, Doo-Sung ; Kim, Tae-Kyun ; Chae, Gyu-Bong ;
Journal of the Korea Concrete Institute, volume 27, issue 5, 2015, Pages 471~480
DOI : 10.4334/JKCI.2015.27.5.471
The building structure is planned to maximize the use of space in recent. It was developed of a hybrid OCB (Optimized Composite Beam) for trying to take advantage of the maximize space. The OCB is composed of the steel h-beam section reinforced by open strands in negative moment zone and the psc concrete section in positive zone. Flexural behaviors of typical architectural bybrid OCB section was investigated. The 15 m OCB specimen was tested under three point static loading system. Following results are obtained from the tests; 1) The OCB with 15 m span develop initial flexural crackings under the 171% of full service loading. 2) Overall deflections of OCB under the service loads are less than those of the allowable limit in KCI Code provision. 3) The crack patterns, failure mode and ultimate load capacity of test specimen and F.E. model in this paper and they are compared to each other. The OCB is verified of structural reliability from the experimental results.
Nonlinear Finite Element Analysis of the Reinforced Concrete Panel using High-Strength Reinforcing Bar
Cheon, Ju-Hyun ; Seong, Dae-Jung ; Cho, Hong-Jae ; Cho, Jae-Yeol ; Shin, Hyun-Mock ;
Journal of the Korea Concrete Institute, volume 27, issue 5, 2015, Pages 481~488
DOI : 10.4334/JKCI.2015.27.5.481
The purpose of this study is to provide analytical method to reasonably predict the overall behavior up to destruction of reinforced concrete panel specimens using high-strength reinforcing bar. A total of 12 specimens of reinforced concrete panels with a wall thickness one-third the size of the actual nuclear containment structures under various loading conditions and design parameters were selected and the analysis was performed using a non-linear finite element analysis program (RCAHEST) was developed by the authors. The mean and coefficient of variation for shear strength at cracking point and maximum shear strength from the experiment and analysis results was predicted 1.03 and 12%, 0.97 and 9%, respectively. For the shear strain at the maximum shear strength from the experiment and analysis results was predicted 0.96 and 30%, respectively. Based on the results, the analysis program that was applied newly modified constitutive equation in this study is judged as having a relatively high reliability for the analysis results.
Shear Strength of Retrofitted RC Squat Wall by Additional Boundary Element
Yi, You-Sun ; Hong, Sung-Gul ; Park, Young-Mi ;
Journal of the Korea Concrete Institute, volume 27, issue 5, 2015, Pages 489~499
DOI : 10.4334/JKCI.2015.27.5.489
This study suggested shear strength prediction model for retrofitted single-layered RC squat wall by providing column element as additional boundary element. This model revised existing shear strength prediction model of shear wall to consider detail and shear deformation capacity of column by assuming the length that concentrated shear deformation of the column is occurred. It was able to suggest additional compatibility condition related to shear strain of retrofitted of retrofitted shear wall at the ultimate state by using this length. Therefore, this study proposed a flow chart for predicting shear strength of the retrofitted shear wall considering this additional condition. Moreover, this study also proposed a method for predicting initial stiffness of the retrofitted shear wall by transforming the wall`s resisting mechanism against to lateral load to a single diagonal strut mechanism. The proposed methods can predict shear strength and initial stiffness of not only the retrofitted shear wall of this study, also infilled RC shear wall in RC frame.
Shear Strength of Steel Fiber Concrete - Plain Concrete Composite Beams
Kim, Chul-Goo ; Park, Hong-Gun ; Hong, Geon-Ho ; Kang, Su-Min ;
Journal of the Korea Concrete Institute, volume 27, issue 5, 2015, Pages 501~510
DOI : 10.4334/JKCI.2015.27.5.501
Composite construction of precast concrete and cast-in-place concrete is currently used for the modular construction. In this case, the use of steel fiber reinforced concrete (SFRC) could be beneficial for precast concrete. However, the shear strength of such composite members (SFRC and cast-in-place concrete) is not clearly defined in current design codes. In the present study, steel fiber composite beam tests were conducted to evaluate the effect of steel fibers on the composite members. The test variables are the area ratio of SFRC and shear reinforcement ratio. The test results showed that when minimum horizontal shear reinforcement was used, the shear strength of composite beams increased in proportion to the area ratio of steel fiber reinforced concrete. However, because of the steel fiber, the composite beams were susceptible to horizontal shear failure. Thus, minimum horizontal shear reinforcement is required for SFRC composite beams.
Experimental Study on Rheological Properties of Alkali Activated Slag Pastes with Water to Binder Ratio
Kim, Byeong-Jo ; Song, Jin-Kyu ; Song, Keum-Il ; Oh, Myeong-Hyeon ; Lee, Bang-Yeon ;
Journal of the Korea Concrete Institute, volume 27, issue 5, 2015, Pages 511~519
DOI : 10.4334/JKCI.2015.27.5.511
Methods such table flow, slump and outflow time have used to be as a main evaluation criteria regards to fluidity of concrete. Since those methods mentioned above have some inaccuracies which are up to its condition of test. Studies that evaluate fluidity applying the rheology has increased its portion in this field. Meanwhile, demands for AAS binder have been increased in accordance with its demand for this market, studies for rheology of AAS binder are little though. Therefore, this paper mainly deals a rheological peculiarity of AAS binder according to its condition of W/B ratio and alkali activators. The fluidity of AAS paste was evaluated with the index of table flow and outflow time. And shear stress following its shear rate was analyzed through rheological test. Rheological parameters were deduced through this rheological test of Bingham model and analyzed its interrelation with fluidity test. As the final outcome, it proposed the interrelation among table flow, yield stress, viscosity and outflow time. In basis of this study, we would like to suggest a reference for mixing AAS mortars and concretes.
Mechanical Characteristics of Ultra High Strength Concrete with Steel Fiber Under Uniaxial Compressive Stress
Choi, Hyun-Ki ; Bae, Baek-Il ; Choi, Chang-Sik ;
Journal of the Korea Concrete Institute, volume 27, issue 5, 2015, Pages 521~530
DOI : 10.4334/JKCI.2015.27.5.521
Design of fiber reinforced ultra-high strength concrete members should be verified with analytical or experimental methods for safety. Members with compressive strength larger than limitation of current design code usually be designed with analytical verification using stress-strain relation of concrete and reinforcements. For this purpose, mechanical characteristics of steel fiber reinforced ultra-high strength concrete were defined under uniaxial compression. Mix proportions of test specimens were based on reactive powder concrete and straight steel fibers were mixed with different volume fraction. Compressive strength of matrix were distributed from 80 MPa to 200 MPa. Effect of fiber inclusion were investigated : increase of compressive strength of concrete, elastic modulus and strain corresponding to peak stress. For the wide range application of investigation, previously tested test specimens were collected and used for investigation and estimation equation. Based on the investigation and evaluation of previous research results and estimation equation of mechanical characteristics of concrete, regression equations were suggested.
Properties of Normal-Strength Mortar Containing Coarsely-Crushed Bottom Ash Considering Standard Particle Size Distribution of Fine Aggregate
Kim, Hyeong-Ki ;
Journal of the Korea Concrete Institute, volume 27, issue 5, 2015, Pages 531~539
DOI : 10.4334/JKCI.2015.27.5.531
Properties of normal-strength mortar containing coarsely-crushed coal bottom ash considering standard particle size distribution of fine aggregate were investigated. Mortar containing raw bottom ash was applied as a reference. By crushing the bottom ash with a particle size larger than fine binder but smaller than fine aggregates, i.e., coarse-crushing, water absorption and specific gravity of the particles could be controlled as similar levels to those of natural fine aggregates. Workability and strength of the mortar were not changed and even increased when the coarsely-crushed bottom ash was added considering standard particle size distribution in Standard Specification for Concrete, while those were decreased when raw bottom ash was added without any treatment. When a replacement ratio of coarsely-crushed bottom ash was less than 30 vol.%, there were no significant decrease in dynamic modulus of elasticity and dry shrinkage of the mortar.
The Seismic Performance of Non-Ductile Reinforced Concrete (RC) Frames with Engineered Cementitious Composite (ECC) Wing Panel Elements
Kang, Dae-Hyun ; Ok, Il-Seok ; Yun, Hyun-Do ; Kim, Jae-Hwan ; Yang, Il-Seung ;
Journal of the Korea Concrete Institute, volume 27, issue 5, 2015, Pages 541~549
DOI : 10.4334/JKCI.2015.27.5.541
This study was conducted to experimentally investigate the seismic retrofitting performance of non-ductile reinforced concrete (RC) frames by introducing engineered cementitious composite (ECC) wing panel elements. Non-ductile RC frame tested in this study were designed and detailed for gravity loads with insufficient or no consideration to lateral loads. Therefore, Non-ductile RC frame were not satisfied on present seismic code requirements. The precast ECC wing panels were used to improve the seismic structural performance of existing non-ductile RC frame. A series of experiments were carried out to evaluate the structural performance of ECC wing panel elements alone a non-ductile RC frame strengthened by adding ECC panel elements. Failure pattern, strength, stiffness and energy dissipation characteristics of specimens were evaluated based on the test results. The test results show that both lateral strength and stiffness were significantly improved in specimen strengthened than non-ductile RC frame. It is noted that ECC wing wall elements application on non-ductile RC frame can be effective alternative on seismic retrofit of non-ductile building.
Evaluation and Adjustment of Lateral Displacement of Complex-shaped RC Tall Buildings Considering the Displacement by Tilt Angle of Each Floor
Kim, Yungon ;
Journal of the Korea Concrete Institute, volume 27, issue 5, 2015, Pages 551~558
DOI : 10.4334/JKCI.2015.27.5.551
Lateral displacement in the most complex-shaped tall buildings is caused by eccentric gravity loads which are induced by the difference in location between a center of mass and a center of stiffness. The lateral displacements obtained from analysis, using conventional procedures, are prone to overestimate the actual values because much of realignment efforts made during construction phase are ignored. In construction sequence analysis, the self-leveling of slab and the verticality of columns/walls could be considered at each construction stage. Moreover, the displacement compensation can be achieved by manual process such as re-centering - locating to global coordinates through surveying. Because the lateral displacement increases with the building height, it is necessary to set up adjustment plan through construction stage analysis in advance in order to result in displacements less than the allowable limits. Because analytical solution includes lots of assumptions, the pre-adjusting displacement should be reasonably controlled with considerations for the uncertainty due to these assumptions.
A Study on the Physical Characteristics of Concrete using Multi-Component Blended Binder According to Warter Reduction Efficiency of Warter Reduction Agent
Kim, Kyung-Hwan ; Oh, Sung-Rok ; Choi, Byung-Keol ; Choi, Yun-Wang ;
Journal of the Korea Concrete Institute, volume 27, issue 5, 2015, Pages 559~568
DOI : 10.4334/JKCI.2015.27.5.559
In this study, multi-component blended concrete mix with fly ash and ground granulated blast furnace slag according to 3 level of type of warter reduction agent (type of 0%, 8% and 16%) and 3 level of water-binder ratio (40%, 45% and 50%) was prepared for evaluation of effect of physical characteristics of concrete using multi-component blended binder according to warter reduction efficiency of warter reduction agent. In addition, concrete mix was carried out repetition test of three times in order to secure the reliability. As a result, compressive strength according to type of warter reduction agent was found that difference of strength was about 20% occurred, warter reduction efficiency of warter reduction agent was showed that a great influence on qualities of concrete. Therefore, reflected the effect of warter reduction efficiency of warter reduction agent, prediction model equations of compressive strength for multi-component blended concrete was proposed, it was found that more than 90% of the high correlation.
A Study on the Cracking Control Effects of Shrinkage Reduction Concrete
Choi, Hyeong-Gil ; Kim, Gyu-Yong ; Noguchi, Takafumi ;
Journal of the Korea Concrete Institute, volume 27, issue 5, 2015, Pages 569~577
DOI : 10.4334/JKCI.2015.27.5.569
The aim of this study is to qualitatively evaluate the cracking control effects of expansive concrete used in reinforced concrete building. The result of experiments in laboratory shows that autogenous shrinkage and drying shrinkage are suppressed by using expansive additive. The tensile stress-strength ratio is lower in expansive concrete than normal concrete under fully restrained condition. Compression stress could be effectively generated in early age in the walls in buildings by the use of expansive additive, and tensile stress due to drying shrinkage at later age eventually decreased. Additionally, visual observation at long-term ages shows that the cracking area of expansive concrete was approximately 35% of normal concrete, which confirms that the use of expansive additive reduces concrete cracking in reinforced concrete buildings.