• Computers and Concrete
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• 제6권6호
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• pp.451-472
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• 2009

Based on a numerical method to analyse the full-range behaviour of prestressed concrete beams with unbonded tendons, parametric studies are carried out to investigate the influence of 11 parameters on the curvature ductility of unbonded prestressed concrete (UPC) beams. It is found that, among various parameters studied, the depth to prestressing tendons, depth to non-prestressed tension steel, partial prestressing ratio, yield strength of non-prestressed tension steel and concrete compressive strength have substantial effects on the curvature ductility. Although the curvature ductility of UPC beams is affected by a large number of factors, rather simple equations can be formulated for reasonably accurate estimation of curvature ductility. Conversion factors are introduced to cope with the difference in partial safety factors, shapes of equivalent stress blocks and the equations to predict the ultimate tendon stress in BS8110, EC2 and ACI318. The same equations can also be used to provide conservative estimates of ductility of UPC beams with compression steel.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.137-138
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• 2009

본 연구는 포스트텐션드 프리스트레스트 콘크리트 포장 (PTCP: Post-Tensioned prestressed Concrete Pavement) 공법의 국내 적용을 위해 수행한 시험 시공 시에 현장 실험을 통해 PTCP의 긴장 시 구조적 거동을 분석하기 위하여 수행되었다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.39-40
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• 2009

본 연구는 교량의 장경간화와 시공단축을 위하여 전구간이 동일한 단면을 가지며 중공이 있는 중공형 프리캐스트 프리스트레스 콘크리트 분절 거더를 개발하고 실용화하기 위한 정착장치를 개발하기 위함이다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회 논문집(I)
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• pp.403-408
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• 1998

The analytical model is developed in order to predict the nonlinear flexural responses of bonded and unbonded prestressed concrete beam which contains advanced composite materials. The block concept is used, which be regarded as an intermediate modeling method between the couple method with one block and the layered method with multiple sliced blocks in a section. The model can successfully predict the flexural behavior of variously reinforced prestressed concrete beams.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1992년도 봄 학술발표회 논문집
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• pp.126-130
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• 1992

Recently, fatigue problem become a critical issue in the design of prestressed concrete bridges due to the increase of traffic volumes and use of high-strength materials. Most existing studies are mainly concerned with the fatigue behavior of component materials only such as concrete, reinforcing bars, and prestressing steels and few studies exist that deals with the fatigue behavior of bridge members. An improved analytic formulation for both uncracked and cracked prestressed concrete composite section with cyclic creep effect is developed to take into account the change of neutral axis with crack propagation. The procedure also enables to investigate serviceability limit states, deflection and crack width. The present study allows more realistic analysis and design of prestressed concrete composite girder bridges under fatigue loadings.

• 한국구조물진단유지관리공학회 논문집
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• 제3권1호
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• pp.113-120
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• 1999

Due to the heterogeneous nature of a concrete, periodic inspections are compulsory to maintenance of quality of concrete structures. The major object of this study is to analyze and investigate experimentally the experimental equation for the estimate of compressive strength of prestressed concrete. In this study, surface hardness method, ultrasonic method are investigated to evaluate strength of concrete specimens. Specimens are cast in laboratory and cores are cut from specimens in order to estimate the accurate strength. These values are used to compare with calculated values from test data. The result shows that the proposed equation can reproduce the results at prestressed concrete beam girders more appropriately than previous equations.

• Structural Engineering and Mechanics
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• 제68권4호
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• pp.475-483
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• 2018

Square tubular columns are commonly used in moment resisting frames, while through-diaphragm connection is the most typical configuration detail to connect the H-shaped beam to the column. However, brittle fracture normally occurs at the complete joint penetration weld between the beam flange and the through-diaphragm due to the stress concentration caused by the geometrical discontinuity. Accordingly, three improved types of through-diaphragm are presented in this paper to provide smooth force flow path comparing to that of conventional connections. Tensile tests were conducted on four specimens and the results were analyzed in terms of failure modes, load-displacement response, yield and ultimate capacity, and initial stiffness. Furthermore, strain distributions on the through-diaphragm, the beam flange plate, and the column face were comprehensively evaluated and discussed. It was found that all the proposed three types of improved through-diaphragm connections were able to reduce the stress concentration in the welds between the beam flange and the through-diaphragm. Furthermore, the stress distribution in connection with longer tapered through-diaphragm was more uniform.

• 대한토목학회논문집
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• 제9권4호
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• pp.27-39
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• 1989

부분(部分) 프리스트레스트 콘크리트는 철근(鐵筋) 콘크리트와 완전(完全) 프리스트레스트 콘크리트의 중간정도(中間程度)의 프리스트레스를 가(加)한 부재(部材)이다. 부분(部分) 프리스트레스트 콘크리트 부재(部材)를 사용(使用)함으로써 완전(完全) 프리스트레스트 콘크리트 부재(部材)의 사용상태(使用狀態)의 이점(利點)과 철근(鐵筋) 콘크리트 부재(部材)의 극한상태(極限常態)의 장점(長點)을 동시(同時)에 취(取)할 수 있다. 본(本) 연구(硏究)는 프리스트레스 정도(程度), 전단철근(剪斷鐵筋)의 배근(配筋)과 단면형태(斷面形態)의 변화(變化)가 부분(部分) 프리스트레스트 콘크리트 부재(部材)의 휨 및 전단(剪斷) 극한거동(極限擧動)에 미치는 영향을 알기 위해서 총 12개의 부분(部分) 프리스트레스트 콘크리트 부재(部材)에 대(對)하여 파괴실험(破壞實險)을 행(行)한 것이다. 이 논문(論文)에서는 실험과정(實驗過程) 기술(記述)하고 실험부재(實驗部材)의 파괴양상(破壞樣相)을 분석(分析)하며, 여러 연구자(硏究者)들이 제안(提案)한 각각의 프리스트레싱 지표(指標)의 유용성(有用性)을 검토(檢討)한다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.397-400
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• 2004

This research aims to estimate the shear strength of the composition of prestressed hollow-core slab and steel beam. The shear strength of prestressed hollow-core slab combined with the steel beam decreases, as the beam deflection increases to a considerable extent. Existing studies on the shear strength of prestressed hollow-core slab are mostly limited to 265mrn- and larger thickness slab on concrete beam. This study investigates the slab of 100mm-thickness combined with steel beam instead of concrete beam. Five shear connector methods are proposed and the shear strength is estimated with or without the beam deflection for each composition method, respectively. Finally the reduction coefficient $(\beta)$ for the transverse shear stress$(\tau_{zx})$, which is critical for the failure of prestressed hollow-core slab, is proposed.

• International Journal of Concrete Structures and Materials
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• 제6권1호
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• pp.49-57
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• 2012

The main objectives of this research were to experimentally evaluate the impact of Carbon Fiber-Reinforced Polymers (CFRP) amount and strip spacing on the shear behavior of prestressed concrete (PC) beams and to evaluate the applicability of existing analytical models of Fiber-Reinforced Polymer (FRP) shear capacity to PC beams shear-strengthened with CFRP. The Ushaped CFRP strips with different spacing were applied externally to the test specimens in order to observe the overall behavior of the prestressed concrete I-beams and the mode of failure of the applied CFRP strips. Results obtained from the experimental program showed that the application of CFRP strips to prestressed concrete I-beams did in fact enhance the overall behavior of the specimens. The strengthened specimens responded with an increase in ductility and in shear capacity. However, it should be noted that the CFRP strips were not effective at all at spacing greater than half the effective depth of the specimen and that fracture of the strips was the dominant failure mechanism of CFRP. Further research is needed to confirm the conclusion derived from the experimental program.