• Title/Summary/Keyword: PC beams

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Classification Schemes of Precast Beam-Column Connections According to Contribution of Deformation Components (변형기여분에 따른 프리캐스트 보-기둥 접합부의 분류방안)

  • Choi, Hyun-Ki;Choi, Chang-Sik
    • Journal of the Korea Concrete Institute
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    • v.26 no.4
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    • pp.545-553
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    • 2014
  • 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.

Evaluation of Horizontal Shear Strength for Concrete Composite Members (콘크리트 합성부재의 수평 전단강도 평가)

  • Suh, Jung-Il;Park, Hong-Gun;Hong, Geon-Ho;Kang, Su-Min;Kim, Chul-Goo
    • Journal of the Korea Concrete Institute
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    • v.28 no.4
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    • pp.407-417
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    • 2016
  • In this study, concrete composite beams were tested under two-point loading to evaluate horizontal shear strength. The test variables were a type of composite members (PC+RC, PSC+RC, SFRC+RC), area ratio of high-strength (60MPa) to low-strength concrete (24 MPa), and transverse reinforcement ratio. The test results showed that the contribution of transverse reinforcements and interface conditions had influence on horizontal shear strength. Existing and previous test results were classified according to test methods and the interface conditions and were compared with the predictions of current design codes. On the basis of test results, an improved design method was proposed.

Analysis of Damping Performance of Hysteretic Dampers of Buckling restrained Braced Type According to eccentricity of school buildings with Torsional irregularities (비틀림 비정형을 가지는 학교건물의 편심율에 따른 좌굴방지가새형 이력댐퍼의 제진성능분석)

  • Kim, Yu-Seong;Lee, Joon-Ho;Kim, Gee-Chul
    • Journal of Korean Association for Spatial Structures
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    • v.23 no.2
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    • pp.37-44
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    • 2023
  • In the case of a school building, even though it is a regular structure in terms of plan shape, if the masonry infill wall acts as a lateral load resisting element, it can be determined as a torsionally irregular building. As a result, the strength and ductility of the structure are reduced, which may cause additional earthquake damage to the structure. Therefore, in this study, a structure similar to a school building with torsional irregularity was selected as an example structure and the damping performance of the PC-BRB was analyzed by adjusting the eccentricity according to the amount of masonry infilled wall. As a result of nonlinear dynamic analysis after seismic reinforcement, the torsional irregularity of each floor was reduced compared to before reinforcement, and the beams and column members of the collapse level satisfied the performance level due to the reduction of shear force and the reinforcement of stiffness. The energy dissipation of PC-BRB was similar in the REC-10 ~ REC-20 analytical models with an eccentricity of 20% or less. REC-25 with an eccentricity of 25% was the largest, and it is judged that it is effective to combine and apply PC-BRB when it has an eccentricity of 25% or more to control the torsional behavior.

Effect of Flexural Performance on U-Shaped Precast Concrete Beams with Noncontact Lapped Splice (비접촉 겹침 이음된 프리캐스트 U형 보의 휨성능에 미치는 효과)

  • Ha, Sang-Su;Kim, Seung-Hun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.12 no.6
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    • pp.119-128
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    • 2008
  • In this study, new moment-resisting precast concrete beam-column joint is proposed for moderate seismic regions. It has the connection reinforcing bars, penetrated the joint and lap-spliced with the bottom bars of precast U-shaped PC beam. To evaluate the performance for noncontact lapped splice, experimental and analytical works were conducted. Major variables for tests are the length of lap, the diameter of connection reinforcing bars, and the distance between lapped bars. Analytic research was performed nonlinear finite element method. Analytic research focused on crack pattern, load-deflection curve, comparison of internal force, evaluation of ductility strains of reinforcement bar. Results of experimental and analytical works show that the these variables has much influence on flexural strength and ductility, and joint behavior.

A Study on the Development of High Strength Concrete for Long Span PSC Beam Bridge(II) (장경간 PSC Beam 교량을 위한 고강도콘크리트의 개발에 관한 연구(II))

  • 백상현;이형준;김기수;엄태선;정원기;황은영
    • Proceedings of the Korea Concrete Institute Conference
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    • 1998.10a
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    • pp.291-296
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    • 1998
  • In the present study, the high strength concrete which is adequate for the long span PC beam above 40 meters has been developed. The optimum cement for high strength concerete was selected through laboratory tests and in-situ mock-up applications. The optical concrete mix design was performed, and the properties of fresh concrete and hardened concrete have been investigated. These results of laboratory study are analized and compared to domestic and foregn design codes and specifications. Finally, the developed high strength concrete was applied to half-scale PSC beams and showed good applicability in field conditions. It is conclude that hte developed high strength concrete can be applied to civil and architectural structures in the field applications.

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An Advisory Expert System for the Designer of Reinforced Concrete Structures (철근 콘크리트 구조물 설계자를 위한 전문가 시스템 개발)

  • 정영식;김철환
    • Proceedings of the Korea Concrete Institute Conference
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    • 1995.04a
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    • pp.372-377
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    • 1995
  • Expert systems which represent the appllication of artificial intelligence research are now nearly 20 years old. It is said that the present technology together with ever- increasing computing applicability of Combined Hypertext-Expert System Techniques to the design of reinforced concrete structures. Hypertext systems allow the user to control the system while expert systems alone don't give the user any control over the system. Therefore the combination of these two techniques, offered by KnowledgePro, may bring us closer to real user-expert communication. The system developed in this work offers information on design in general by reorganizing ACI Manual 318-89, detailed stress analysis and cross sectional design of simple PC/RC beams and optimum design of reinforced concrete building frames. The system also includes the author's earlier work on guidance to identify types of cracks in concrete. It is also includes the author's earlier work on guidance to identify types of cracks in concrete. It is also demonstrated how well and conveniently existing programs can be used by reorganizing the user manuals in the context of hypertext.

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Inelastic Behavior of Post-tensioned Wide Beam System with different Reinforcement ratios within Column core (포스트텐션을 도입한 넓은 보에서 기둥 폭 내부에 배근된 보강재의 정착비에 따른 비탄성 거동 평가)

  • Choi Yun-Cheul;Lim Jae-Hyung;Moon Jeong-Ho;Lee Li-Hyung;Kwon Ki-Hyuk
    • Journal of the Korea Concrete Institute
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    • v.17 no.1 s.85
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    • pp.85-94
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    • 2005
  • Post-tensioned Precast concrete System(PPS) consists of U-shaped precast wide beams and concrete column. The continuity of beam-column joint is provided with floor concrete cast on the PC shell beam and post-tensioning. The purpose of this paper is to evaluate the response of PPS interior beam-column joint subjected to cyclic lateral loading. To this end, an experimental investigation was performed with three half-scale specimens of interior connection. The design parameters are the amount of beam reinforcement placed inside the joint core. The test results showed that cracks were distributed well without my significant degradation of strength and ductility. Also, it was found that the prestressing may affect to alter the torsional crack angle. And the specimens sufficiently resist up to limiting drift ratio of 0.035 in accordance with the provisional by ACl of acceptance criteria for concrete special moment frames.

A Numerical and Experimental Study on Structural Performance of Noncomposite and Composite Eco-Arch Structures subjected to Concentrated Loads (집중하중을 받는 비합성.합성 생태아치구조물의 성능평가를 위한 수치해석 및 모형실험 연구)

  • Kim, Yong-Hee;Park, Jong-Sup;Lee, Young-Ho;Oh, Min-Su
    • Journal of Korean Society of Steel Construction
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    • v.22 no.2
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    • pp.173-183
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    • 2010
  • In this study, noncomposite and composite eco-arch structures with I-beams and precast concrete(PC) decks were investigated. Four finite-element models(a steel-girder model, a steel-girder-and-several-PC-panels model, a three-steel-girder model, and a three-steel-girder-and-several-PC-panels model) using a general finite-element program, ABAQUS, were reviewed to predict the strength of the noncomposite and composite arch structures. Based on the results of the finite- element analysis, the behaviors of the four models were investigated, and deflection and strain gauges for the experimental specimen consisting of three steel girders and several PC panels were set up to obtain the ultimate strength. The ultimate strength of the specimen was estimated to be 1,961kN. The ultimate strength was much larger than the 1,380-kN load calculated using AASHTO LRFD Bridge Design Specifications(2007). The noncomposite and composite arch bridges were found to have enough strength for safety.

THE EFFECT OF DIFFERENT CURING MODES ON COMPOSITE RESIN/DENTIN BOND STRENGTH IN CLASS ICAVITIES (1급 와동에서 상아질과 복합레진의 결합강도에 대한 중합방법의 효과)

  • Baek, Shin-Young;Cho, Young-Gon;Song, Byeong-Choon
    • Restorative Dentistry and Endodontics
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    • v.33 no.5
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    • pp.428-434
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    • 2008
  • The purpose of this study was to compare the microtensile bond strength in Class I cavities associated with different light curing modes of same light energy density. Occlusal enamel was removed to expose a flat dentin surface and twenty box-shaped Class I cavities were prepared in dentin. Single Bond (3M Dental product) was applied and Z 250 was inserted using bulk technique. The composite was light-cured using one of four techniques, pulse delay (PD group), soft-start (SS group), pulse cure (PC group) and standard continuous cure (CC group). The light-curing unit capable of adjusting time and intensity (VIP, Bisco Dental product) was selected and the light energy density for all curing modes was fixed at $16J/cm^2$. After storage for 24 hours, specimens were sectioned into beams with a rectangular cross-sectional area of approximately $1mm^2$ Microtensile bond strength $({\mu}TBS)$ test was per- formed using a univel·sal testing machine (EZ Test, Shimadzu Co.). The results were analyzed using oneway ANOVA and Tukey's test at significance level 0.05. The ${\mu}TBS$ of PD group and SS group was higher than that of PC group and CC group. Within the limitations of this in vitro study, modification of curing modes such as pulse delay and soft start polymerization can improve resin/dentin bond strength in Class I cavities by controlling polymerization velocity of composite resin.

Evaluation of Flexural Performance of Eco-Friendly Inorganic Binding Material RC Beams Using Sodium Activator (나트륨계 알칼리 활성화제를 사용한 친환경 무기결합재 철근콘크리트 보의 휨성능 평가)

  • Ha, Gee-Joo;Kim, Jin-Hwan;Jang, Kie-Chang
    • Journal of the Korea Concrete Institute
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    • v.25 no.3
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    • pp.261-269
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    • 2013
  • In this study, it was developed eco-friendly inorganic binding material concrete using ground granulated blast furnace slag and alkali activator (water glass, sodium hydroxides). Eight reinforced concrete beam using inoganic binding material concrete were constructed and tested under monotonic loading. The major variables were mixture ratio of alkali activator, type of admixture and admixture. Experimental programs were carried out to improve and evaluate the flexural performance of such test specimens, such as the load-displacement, the failure mode, the maximum load carrying capacity, and ductility capacity. All the specimens were modeled in scale-down size. The eco-friendly concrete using inorganic binding material encouraged alkali activation reaction was rapidly hardening speed and showed possibility as a high strength concrete. Also, the RC beams using new materials showed similar behavior and failed similarly with RC beam used portland cement. It is thought that eco-friendly inorganic binding material concrete can be used with construction material and product as a basic research to replace cement concrete. If there is application to structures in PC member as well as production of 2nd concrete product, it could be improved the productivity and reduction of construction duration etc.