• Title/Summary/Keyword: PSC Beams

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Growth of Time-Dependent Strain in Reinforced Cement Concrete and Pre-stressed Concrete Flexural Members

  • Debbarma, Swarup Rn.;Saha, Showmen
    • International Journal of Concrete Structures and Materials
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    • v.6 no.2
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    • pp.79-85
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    • 2012
  • This paper presents the differences in growth of time-dependent strain values in reinforced cement concrete (RCC) and pre-stressed concrete (PSC) flexural members through experiment. It was observed that at any particular age, the time-dependent strain values were less in RCC beams than in PSC beams of identical size and grade of concrete. Variables considered in the study were percentage area of reinforcement, span of members for RCC beams and eccentricity of applied pre-stress force for PSC beams. In RCC beams the time-dependent strain values increases with reduction in percentage area of reinforcement and in PSC beams eccentricity directly influences the growth of time-dependent strain. With increase in age, a non-uniform strain develops across the depth of beams which influence the growth of concave curvature in RCC beams and convex curvature in PSC beams. The experimentally obtained strain values were compared with predicted strain values of similar size and grade of plane concrete (PC) beam using ACI 318 Model Code and found more than RCC beams but less than PSC beams.

Behaviors of Joints with Perfobond Rib Shear Connectors in Steel-PSC Hybrid System (Perfobond Rib을 적용한 강-PSC 혼합구조 연결부의 거동 평가)

  • Kim, Sang Hyo;Lee, Chan Goo;Yoon, Ji Hyun;Won, Jeong Hun
    • Journal of Korean Society of Steel Construction
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    • v.21 no.6
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    • pp.647-657
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    • 2009
  • This paper studies the behavior of joints in steel-PSC (prestressed concrete) hybrid beams, which is necessary for the application of hybrid beams to spliced girder bridges, and proposes a new type of joint with improved construction convenience and structural behavior. In the proposed joint, perfobond rib shear connectors are attached to the upper and lower plates, which are expanded from the steel girders and located between the steel girder and the PSC girder. The experimental tests were performed on hybrid beams with the suggested joint. The results showed that all the beams had similar ultimate strengths and failure modes, due to the failure of their PSC parts. The composite action of the perfobond ribs was verified by examining the initial stiffness and cracks of the test beams. In addition, the test beams showed a higher degree of ultimate strength than the beams with stud shear connectors in the joints that had been previously studied. Thus, the proposed joint is effective for the steel-PSC hybrid beam.

An Experimental Study on Structural Behavior of PSC Beams Reinforced with Steel Fibers (강섬유보강 PSC 보의 구조거동 실험연구)

  • Yang, In-Hwan;Joh, Chang-Bin;Kim, Byung-Suk;Joo, Kun-Hyung
    • Proceedings of the Korea Concrete Institute Conference
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    • 2010.05a
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    • pp.101-102
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    • 2010
  • The flexural performance of high-strength prestressed concrete (PSC) beams reinforced with steel fibers is described. This study aims at determining the structural behavior of steel fiber reinforced concrete beams such as failure mode, capacity in flexure, crack patterns, strains in concrete.

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Investigation of the Behavior of Lateral Load Distribution of Railway PSC Girder Bridges (철도 PSC빔교의 하중횡분배 거동에 관한 고찰)

  • Jung, Chan-Mook
    • The Journal of the Korea Contents Association
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    • v.11 no.1
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    • pp.422-428
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    • 2011
  • This paper presents results from the theoretical analysis of the lateral load distribution for a railway bridge designed with PSC girders which is one of most popular types of bridge in Korea. Typically, 3 sets of intermediate cross beams within a span have been installed for lateral load distribution. In this paper, the effect on the lateral load distribution by the number of intermediate cross beams were examined by both simple grillage analysis and finite element method. This study showed that at least, one set of cross beams at midspan should be needed to ensure the proper load distribution. However, the effect of cross beams on the load distribution becomes not significant though more than one set of cross beams are installed. Therefore, only one set of cross beans at midspan is recommended for constructibility and economic efficiency.

A Study on Strengthening of PSC Beam by Static Experiment - Glass fiber sheeting and External post-tensioning methods - (PSC 부재의 성능개선기법에 관한 정적 실험 연구 - 유리섬유 부착 공법과 외부 후긴장 보강 공법 -)

  • Kim, Hyun-Ho;Song, Jae-Pil;Kim, Ki-Bong;Chung, Young-Soo
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.7 no.1
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    • pp.157-163
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    • 2003
  • Recently, the number of Prestressed Concrete(PSC) bridges needed repair and retrofit because of the increase of heavy traffic loads and aging of concrete materials. But there are a few related researches about strengthening PSC bridges. In this study, the practicability of strengthening methods for PSC beam were studied by the static experimental method. PSC beams in length of 6m were made with concrete slabs. Glass fiber sheeting and external post-tensioning methods were used for strengthening PSC beams. Some beams were strengthened after cracks to investigate the applicability for cracked bridges. As a result, there strengthening methods were efficient at increasing the cracking loads and the failure load, to decrease deflection and prevent cracks. In the case of using glass fiber retrofit methods, it should be careful in the anchorage problems for preventing the bonding failure.

An Experimental Study on Damage Detection of PSC Beams using Vibration Test (진동 시험을 통한 PSC 보의 손상탐지에 대한 실험적 연구)

  • Jung Woo-Tae;Park Jong-Sup;Park Young-Hwan;You Young-Jun
    • Proceedings of the Korea Concrete Institute Conference
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    • 2004.05a
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    • pp.96-99
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    • 2004
  • PSC bridges are deteriorated by many reasons and are difficult to measure residual prestressing forces. It is considered that one of the methods for measuring the prestressing forces is vibration test. This study reports on the change of natural frequency for damaged PSC beams using vibration test which have been carried out to evaluate the effects of cross-section and prestressing forces on natural frequency of PSC beams. According to the results of vibration test results, natural frequency is more sensitive to the changes of cross-section than those of prestress.

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Identification of prestress-loss in PSC beams using modal information

  • Kim, Jeong-Tae;Yun, Chung-Bang;Ryu, Yeon-Sun;Cho, Hyun-Man
    • Structural Engineering and Mechanics
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    • v.17 no.3_4
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    • pp.467-482
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    • 2004
  • One of the uncertain damage parameters to jeopardize the safety of existing PSC bridges is the loss of the prestress force. A substantial prestress-loss can lead to severe problems in the serviceability and safety of the PSC bridges. In this paper, a nondestructive method to detect prestress-loss in beam-type PSC bridges using a few natural frequencies is presented. An analytical model is formulated to estimate changes in natural frequencies of the PSC bridges under various prestress forces. Also, an inverse-solution algorithm is proposed to detect the prestress-loss by measuring the changes in natural frequencies. The feasibility of the proposed approach is evaluated using PSC beams for which a few natural frequencies were experimentally measured for a set of prestress-loss cases. Numerical models of two-span continuous PSC beams are also examined to verify that the proposed algorithm works on more complicated cases.

A Reliability Analysis considering the Second Composite Effect in the To-Box Reinforcement of Deteriorated PSC Beam Bridge (PSC Beam의 박스형 보강 시 이차합성을 고려한 신뢰성해석)

  • Han Sung-Ho;Cho Chang-Joo;Bang Myung-Seok;Shin Jae-Chul
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2005.04a
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    • pp.400-407
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    • 2005
  • The reinforcing effect of modified structure of PSC beams is analyzed in this study. The PSC beams are closed by precast half panels embeding PS tendons at the bottom flange of I-bear The stiffness of box structure is larger and the PS force at half panels makes a time-dependent upward camber of superstructures. The superstructure becomes a second composite structure among 3 elements-PSC ben RC slab, PSC Panel. The time-dependent creep and shrinkage effect at PSC Panels and structural behavior is verified considering construction sequences. The optimal range of to-box reinforcing method is surveyed through reliability analysis.

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Shear Behavior of Post-tensioning PSC Beams with High Strength Shear Reinforcement (고강도 전단보강철근을 사용한 포스트텐션 프리스트레스트 콘크리트 보의 전단거동 평가)

  • Jun, Byung-Koo;Lee, Jea-Man;Lim, Hye-Sun;Lee, Jung-Yoon
    • Journal of the Korea Concrete Institute
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    • v.28 no.1
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    • pp.33-40
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    • 2016
  • 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.

Prediction of the Torsional Strength of PSC Beams Subjected to Pure Torsion (순수비틀림을 받는 프리스트레스트 콘크리트 보의 비틀림 강도 예측)

  • 박지선;이정윤
    • Proceedings of the Korea Concrete Institute Conference
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    • 2002.10a
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    • pp.179-184
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    • 2002
  • The evaluation equation of torsional moment for prestressed concrete members in ACI 318-95 ignores the contribution of concrete, T$_{c}$. Several research indicates that the current ACI code is not successful in predicting the observed torsional moment of the PSC beams with reasonable accuracy. This paper proposes an evaluation equation of torsional moment taking into account the inter-effects between concrete and torsional reinforcement on the torsional resistance of the PSC beams. According to the comparison with the 31 test results, the torsion equation in ACI code underestimated or overestimated the real torsional moment of prestressed concrete beams. On the other hand, the proposed torsional equation is shown to be in a good agreement with experimental results.s.

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