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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 28, Issue 4 - Aug 2016
Volume 28, Issue 3 - Jun 2016
Volume 28, Issue 2 - Apr 2016
Volume 28, Issue 1 - Feb 2016
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Flexural Capacity of Precast Concrete Triple Ribs Slab
Hwang, Seung-bum ; Seo, Soo-yeon ; Lee, Kang-cheol ; Lee, Seok-hyun ;
Journal of the Korea Concrete Institute, volume 28, issue 1, 2016, Pages 3~11
DOI : 10.4334/JKCI.2016.28.1.003
The concern about hollow core PC slab has been increased to improve the workability during a construction of building by reducing self weight of structural members. In this manner, recently, TRS (Tripple Ribs Slab) was developed as a new type of half PC slab system. TRS member consists of the triple webs and the bottom flange prestressed by strands. The slab system is completed by casting of topping concrete on the TRS after filling styrofoam between the webs. This paper, presents a flexural experiment to investigate the flexural capacity of the TRS. Five full scale TRS members were made and tested under simple support condition to be failed by flexure and their strength was evaluated by code equations; the variables in the test are the depth and the presence of topping or raised spot formed when slip-forming. In addition, a nonlinear sectional analysis was performed for the specimens and the result was compared with the test results. From the study, it was found that the TRS has enough flexural strength and ductility to resist the design loads and its strength can be suitably predicted by using code equations. The raised spot did not affect the strength so that the spot need not to be removed by doing additional work. For the more accurate prediction of TRS's flexural behavior by using nonlinear sectional analysis, it is recommended to consider the concrete's brittle property due to slip-forming process in the modeling.
Evaluation on Flexural Behavior of Hybrid Beams with Rigid Joint Connecting Steel and Precast Concrete Elements
Seo, Eun-A ; Yang, Keun-Hyeok ; Hong, Seung-Hyun ;
Journal of the Korea Concrete Institute, volume 28, issue 1, 2016, Pages 13~21
DOI : 10.4334/JKCI.2016.28.1.013
A hybrid precast concrete beam system with a simple rigid connection was proposed to compensate the limitations and shortcomings of the conventional bolt connection associated with the H-beams embedded into concrete beams. Three beam specimens with fixed both ends were tested under one-point top cyclic loading to explore the effectiveness of the developed hybrid beam system in transferring externally applied flexure to a column. The main parameter considered was the length (
) of H-beam, which was selected to be
is the distance from the support to the point of inflection. All beam specimens showed a better displacement ductility ratio than the reinforced concrete beams with the same longitudinal reinforcement index, indicating that the cyclic load-deflection curve and ductility were insignificantly affected by
. The continuous strain distribution along the beam length and the prediction of the ultimate load based on the collapse mechanism ascertained the structural adequacy of the developed rigid connection.
Estimation of Shrinkage Behavior and Stress of Expansive Concrete on Buildings
Choi, Hyeong-Gil ; Kim, Gyu-Yong ; Noguchi, Takafumi ; Hama, Yukio ;
Journal of the Korea Concrete Institute, volume 28, issue 1, 2016, Pages 23~31
DOI : 10.4334/JKCI.2016.28.1.023
In this study, Based on the constructed model in advance, we suggested the macro prediction method of shrinkage cracking reduction in concrete using expansive additives, and the method was verified. In addition, extended application of model to building, the strain of walls and slabs on building was estimated by model and the generated stress was estimated thereby comparing this with the result by existing method to verify the model's applicability and the validation of our model. From examination of theoretical model for concrete using expansive additives to examination for building levels, furthermore suggests the macro prediction method for shrinkage reduction and cracking control effects was can be supply practical data in application of expansive concrete and utility in the future.
Shear Behavior of Post-tensioning PSC Beams with High Strength Shear Reinforcement
Jun, Byung-Koo ; Lee, Jea-Man ; Lim, Hye-Sun ; Lee, Jung-Yoon ;
Journal of the Korea Concrete Institute, volume 28, issue 1, 2016, Pages 33~40
DOI : 10.4334/JKCI.2016.28.1.033
The KCI-12 and ACI 318-14 design codes limit the maximum yield strength of shear reinforcement to prevent concrete compressive crushing before the yielding of shear reinforcement. The maximum yield strength of shear reinforcement is limited to 420 MPa in the ACI 318-14 design code, while limited to 500 MPa in the KCI-12 design code. A total of eight post-tensioning prestressed concrete beams with high strength shear reinforcement were tested to observe the shear behavior of PSC beams and the applicability of the high strength reinforcement was thus assessed. In the all PSC beam specimens that used stirrups greater than maximum yield strength of shear reinforcement required by the ACI 318-14 design code, the shear reinforcement reached their yield strains. The observed shear strength of tested eight PSC beams was greater than the calculated ones by the KCI-12 design codes. In addition, the diagonal crack width of all specimens at the service load was smaller than the crack width required by the ACI 224 committee. The experimental and analytical results indicate that the limitation on the yield strength of shear reinforcement in the ACI 318-14 design code is somewhat under-estimated and needs to be increased for high strength concrete. Also the application of high strength materials to PSC is available with respect to strength and serviceability.
Effects of Shrinkage Reducing Agent (SRA) Type and Content on Mechanical Properties of Strain Hardening Cement Composite (SHCC)
Han, Seung-Ju ; Jang, Seok-Joon ; Khil, Bae-Su ; Choi, Mu-Jin ; Yun, Hyun-Do ;
Journal of the Korea Concrete Institute, volume 28, issue 1, 2016, Pages 41~48
DOI : 10.4334/JKCI.2016.28.1.041
This research investigates the effects of shrinkage reducing agent (SRA) on the mechanical behavior of strain-hardening cement composite (SHCC). SHCC material with specified compressive strength of 50 MPa was mixed and tested in this study. All SHCC mixes reinforced with volume fraction of 2.2% polyvinyl alcohol (PVA) fiber and test variables are type and dosage of shrinkage reducing agents. The shrinkage reducing materials used in this study are phase change material as the thermal stress reducing materials that have the ability to absorb or release the heat. The effect of SRA was examined based on the change in length caused by shrinkage and hardened mechanical properties, specially compressive, tensile and flexural behaviors, of SHCC material. It was noted that SRA reduces change in length caused by shrinkage at early age. SRA can also improve the tensile and flexural strengths and toughness of SHCC material used in this study.
Evaluation for Fundamental Properties of Concrete mixed with Pyroclastic Flow Deposit
Choi, Hyeong-Gil ; Kim, Gyu-Yong ; Noguchi, Takafumi ;
Journal of the Korea Concrete Institute, volume 28, issue 1, 2016, Pages 49~57
DOI : 10.4334/JKCI.2016.28.1.049
The aim of this study was to investigate the fundamental properties of pyroclastic flow deposit (PFD), and evaluate the fresh and strength properties of concrete mixed with PFD by indoor tests. The fresh properties, strength properties, shrinkage properties, and durability of the concrete mixed with PFD were also evaluated by outdoor plant tests. the harmful alkali-silica reaction did not occur by mixing concrete with PFD. ages. Moreover, no difficulty was found to be associated with concrete manufacture in the plant because no change in air contents and noticeable slump loss occurred by mixing concrete with PFD. The strength properties, shrinkage properties, and durability of the concrete mixed with PFD were also compared with those of normal concrete. With a suitable temperature control and curing method of concrete, the concrete mixed with PFD is considered to be useful in the construction material field.
Microstructure and Properties of Mortar Containing Synthetic Resin using Image Analysis
Lee, Binna ; Min, Jiyoung ; Lee, Jong-Suk ; Lee, Jang-Hwa ;
Journal of the Korea Concrete Institute, volume 28, issue 1, 2016, Pages 59~65
DOI : 10.4334/JKCI.2016.28.1.059
Commercial synthetic resins with great amount of hydrogen atoms were investigated for neutron shielding aggregates. Total three types of resins were considered in this study: high density polyethylene (HDPE), polypropylene (PP), and ultra molecular weight polyethylene (UPE). When these resins replaced 20, 40, 60 vol% of fine aggregates, mechanical properties were first evaluated including compressive and tensile strengths, and then image/microstructure analyses such as cross-section analysis, SEM, and X-ray CT were performed. The results showed that the compressive and tensile strengths decreased with the increase of replacement ratio of HDPE and PP, which was found through image analysis that it was closely related to the distribution of resins at the failure surface of test specimens. The strength reduction of UPE was quite small compared to HDPE and PP but it abruptly increased when the replacement level exceeded 60 vol%. The results of microstructure analyses indicated that the replacement level significantly affected the amount of air void so that it is critical to determine the reasonable amount of UPE to make cementitous materials for neutron shielding.
Flowability and Strength of Cement Composites with Different Dosages of Multi-Walled CNTs
Ha, Sung-Jin ; Kang, Su-Tae ;
Journal of the Korea Concrete Institute, volume 28, issue 1, 2016, Pages 67~74
DOI : 10.4334/JKCI.2016.28.1.067
With several different dosages of multi-walled CNTs which was 0.1, 0.3, and 0.5% of the weight of binder, the fluidity in fresh CNT cement composites, as well as the strength and strength development with age of the hardened composites were investigated in this experimental study. The experimental results from flow test indicated that the increase in the dosage of CNTs badly impacted on the workability of fresh composites, and the results from rheological measurements presented the decrease in plastic viscosity and the increase in yield stress according to the amount of CNTs. In addition, the thixotrophy in the flow curve obtained from the rheology test was observed more noticeably in the composites with higher dosage of CNTs. With the experiments on the strength properties, the improvement of both compressive and tensile strengths with the increase of CNTs dosage could be obtained. Moreover, early strength development by adding CNTs was found when it was compared with plain cementious matrix without CNT.
Performance Assessment of Solid Reinforced Concrete Columns with Triangular Reinforcement Details
Kim, Tae-Hoon ; Lee, Seung-Hoon ; Lee, Jae-Hoon ; Shin, Hyun Mock ;
Journal of the Korea Concrete Institute, volume 28, issue 1, 2016, Pages 75~84
DOI : 10.4334/JKCI.2016.28.1.075
The purpose of this study was to investigate the performance of solid reinforced concrete columns with triangular reinforcement details. The proposed reinforcement details has economic feasibility and rationality and makes construction periods shorter. A model of solid reinforced concrete columns with triangular reinforcement details was tested under a constant axial load and a quasi-static, cyclically reversed horizontal load. A computer program, RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology), for the analysis of reinforced concrete structures was used. The used numerical method gives a realistic prediction of performance throughout the loading cycles for several test specimens investigated. As a result, proposed triangular reinforcement details for material quantity reduction was superior to existing reinforcement details in terms of required performance.
Flexural Performance of Slabs Strengthened by Fiber-Reinforced Polymer Sheet with Hydrophilic Epoxy
Ju, Hyunjin ; Han, Sun-Jin ; Cho, Hae-Chang ; Lee, Deuck Hang ; Kim, Kang Su ;
Journal of the Korea Concrete Institute, volume 28, issue 1, 2016, Pages 85~94
DOI : 10.4334/JKCI.2016.28.1.085
In this study, the hydrophilic chemical grout using silanol (HCGS) was introduced to overcome the limitations of conventional epoxy resin which have been used for strengthening reinforced concrete (RC) structures. Then, flexural tests on the RC slabs strengthened by FRP sheets were conducted. Three slab specimens were tested in this study; a control specimen with no strengthening, and two specimens strengthened by a typical epoxy resin or HCGS, respectively, as a binder between the slabs and the FRP sheets. In addition, an analytical model was developed to evaluate the flexural behavior of strengthened slab members, considering the horizontal shear force at the interface between concrete slabs and FRP sheets. The analysis results obtained from the proposed model indicated that the strengthened specimens showed fully composite behavior before their flexural failure. Especially, the specimen strengthened by HCGS, which can overcome the limitations of conventional epoxy resin, showed a similar flexural performance with that strengthened by a conventional epoxy resin.
Design of Ground Floor Slab According to the Method for Evaluating the Tensile Performance of Steel Fiber Reinforced Concrete
Lee, Jong-Han ; Cho, Baik-Soon ; Cho, Chang-Oh ;
Journal of the Korea Concrete Institute, volume 28, issue 1, 2016, Pages 95~104
DOI : 10.4334/JKCI.2016.28.1.095
Flexural strength of concrete ground slab reinforced with steel fiber is evaluated using the equivalent flexural strength ratio of steel fiber reinforced concrete based on the yield line theory. Recently, the European standard specifies that the tensile performance of the steel fiber reinforced concrete be evaluated directly from the residual flexural strength after the cracking of concrete. Thus, in the study, an experiment was carried out to evaluate the conventional equivalent flexural strength ratio and the residual flexural strength of the steel fiber reinforced concrete. Then the design flexural strength was investigated according to the location of a point load, based on the ratio of the radius of contact area of the load to the radius of relative stiffness. Design flexural capacity obtained from ACI 360R-10 was smaller than that from TR 34 (2003 & 2013). In addition, TR 34 (2013), which evaluates the design flexural capacity based on the residual flexural strength, showed slightly smaller value than TR 34 (2003).
Effect of Recycled Coarse Aggregate on Compressive Strength and Mechanical Properties of Concrete
Yang, In-Hwan ; Jeong, Joon-Young ;
Journal of the Korea Concrete Institute, volume 28, issue 1, 2016, Pages 105~113
DOI : 10.4334/JKCI.2016.28.1.105
Most studies on mechanical properties of concrete with recycled aggregate was focused on the concrete with compressive strength of less than 40 MPa. Therefore, this paper concerns the compressive strength and mechanical properties of concrete with compressive strength of greater than 40 MPa containing recycled coarse aggregate (RCA). The experimental parameters were compressive strength level and replacement ratio of RCA. Compressive strength level was 45 and 60 MPa, and replacement ratio of RCA was 30, 50, 70 and 100%. The results of the test were discussed: compressive strength, elastic modulus, split tensile strength and modulus of rupture. Test results of elastic modulus were compared to the design code predictions. The design code predictions for elastic modulus overestimated the experimental results. However, the design code predictions for modulus of rupture were generally in agreement with the measured values.