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  • Title/Summary/Keyword: reinforced joints

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A study on the Drilling according to the Stacking Sequence of the CFRP (탄소섬유강화플라스틱의 적층구성에 따른 드릴 가공에 관한연구)

  • Kim, S.B.;Shin, H.G.;Kim, T.Y.
    • Journal of the Korean Society of Mechanical Technology
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    • v.13 no.2
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    • pp.1-7
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    • 2011
  • The CFRP composite has a lot of merits such as mechanical characteristic, light and thermal resistance. For these merits, CFRP is applied to so many industrial area. In order to use the composite materials in the aircraft structures or machine elements, accurate surfaces for bearing mounting or joints must be provided, which require precise, machining. In this study, the specimens differentiating the stacking sequence of 5kinds were used. When drilling the carbon fiber reinforced plastics, it was checked on whether the stacking sequence reached any effect on the cutting force. Also relationship between the drill diameter is examined from the drilling experiment, which is the drilling of Fabric, Unidirectional specimen with ∅6mm, ∅10mm, ∅12mm cemented carbide drill. Considering cutting force and drilling diameter, the results are analyzed.

Behaviour of continuous prestressed concrete beams with external tendons

  • Chan, K.H. Enoch;Au, Francis T.K.
    • Structural Engineering and Mechanics
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    • v.55 no.6
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    • pp.1099-1120
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    • 2015
  • External prestressing has been applied to both new construction and retrofitting of existing reinforced and prestressed concrete structures. Continuous beams are preferred to simply supported beams because of economy, fewer movement joints and possible benefits from moment redistribution. However, this paper argues that continuous prestressed concrete beams with external unbonded tendons demonstrate different full-range behaviour compared to reinforced concrete (RC) beams. Applying the same design approach for RC to external prestressing may lead to design with a lower safety margin. To better understand the behaviour of continuous prestressed concrete beams with unbonded tendons, an experimental investigation is performed in which nine such specimens are tested to failure. The full-range behaviour is investigated with reference to moment-curvature relationship and moment redistribution. The amounts of moment redistribution measured in the experiments are compared with those allowed by BS 8110, EC2 and ACI 318. Design equations are also proposed to estimate the curvature ductility index of unbonded prestressed concrete beams.

Behavior of Reinforced Concrete Slabs Connected with Hinge Joints of Remodelling Buildings (리모델링 건물의 활절점에 의하여 연결된 철근콘크리트 바닥판의 거동 평가)

  • Sim Kyu-Kwan;Kim Sang-Sik;Lee Jung-Yoon;Choi kwang-Ho;Im Juhyeuk
    • Journal of the Korea Concrete Institute
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    • v.17 no.5 s.89
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    • pp.761-768
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    • 2005
  • Lately outmoded and functionally obsolete buildings constructed in 1960s and 1970s are often remodelled and restored. Even though there are not serious structural defects in the existing buildings, many old buildings have been reconstructed to improve residence quality or to extend residence area of the buildings. The experimental or theoretical research on plane expansion of RC apartments is quite scare. In this research, 12 specimens and 19 RC slabs connected by hinged joints were tested. The new slab was connected to the existing slab by hinge joints injecting dowel bars between two slabs. Main parameters of the slabs are types of the dowel bars (D13 and D19), spacing of the dowel bars (150mm, 300mm, and 450mm), and the locations of the steel bars in the existing slabs. The test results indicated that the shear strength of the RC test slabs having various types of dowel bars was about twice that calculated by the ACI 318-02 code. All slabs failed in concrete spatting and the dowel steel bars did not reach their yield strengths.

Analytical modelling and behavior of RC beam-column joints (RC 보-기둥 접합부의 해석 모델링과 거동)

  • 우성우;이한선
    • Proceedings of the Korea Concrete Institute Conference
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    • 2003.11a
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    • pp.388-391
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    • 2003
  • In this study, the experimental results were simulated by using a nonlinear analysis programs IDARC 2D and RUAUMOKO 2D. These programs use a global Takeda-like model. The objectives of this study is to verify the correlation between the experimental and analytical responses of reinforced concrete (RC) frame and to provide the calibration to the available static inelastic analysis techniques. The evaluation of the accuracy of analytical simulation by IDARC 2D and RUAUMOKO 2D leads to the conclusion that the global behaviors can be, in general, simulated with limited accuracy in the linear analysis as detailing.

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Seismic Analysis for Performance Assessment of Precast Segmental PSC Bridge Columns (프리캐스트 세그먼트 PSC 교각의 성능평가를 위한 지진해석)

  • Kim, Tae-Hoon;Park, Se-Jin;Kim, Young-Jin;Shin, Hyun-Mock
    • Journal of the Earthquake Engineering Society of Korea
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    • v.13 no.2
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    • pp.15-27
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    • 2009
  • The purpose of this study is to investigate the seismic behavior of precast segmental PSC bridge columns. For the analysis of reinforced concrete structures, a computer program named RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology) is used. To represent the interaction between tendon and concrete of a prestressed concrete member, a bonded or unbonded tendon element based on the finite element method is used. A joint element is modified to predict the inelastic behaviors of segmental joints. The solution of the equations of motion is obtained by numerical integration using Hilber-Hughes-Taylor (HHT) algorithm. The proposed numerical method gives a realistic prediction of seismic behavior throughout the input ground motions for numerical examples.

Finite element modelling of FRP-strengthened RC beam-column connections with ANSYS

  • Shrestha, Rijun;Smith, Scott T.;Samali, Bijan
    • Computers and Concrete
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    • v.11 no.1
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    • pp.1-20
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    • 2013
  • There is an abundance of research on the strengthening of reinforced concrete (RC) structural elements such as beams, columns and slabs with fibre reinforced polymer (FRP) composites. Less research by comparison has been conducted on the strengthening of RC beam-column connections and the majority of such research has been predominantly experimental to date. Few existing experimental studies have reported extensive instrumentation of test specimens which in turn makes understanding the behavior of the connections and especially the contributions made by the FRP difficult to ascertain. In addition, there has been even more limited research on the analytical and numerical modelling of FRP-strengthened connections. In this paper, detailed descriptions of key strategies to model FRP-strengthened RC connections with finite elements are provided. An extensively instrumented and comprehensively documented set of experiments on FRP-strengthened connections is firstly presented and finite element models are then constructed using ANSYS. The study shows that the finite element approach is able to capture the overall behavior of the test specimens including the failure mode as well as the behavior of the FRP which will most importantly lead to a detailed understanding of the FRP and the future development of rational analytical models. The finite element models are, however, unable to model the stiffness of the connections with accuracy in the ultimate load range of response.

Experimental investigation on the seismic behavior of reinforced concrete column-steel beam subassemblies

  • Xiong, Liquan;Men, Jinjie;Ren, Ruyue;Lei, Mengke
    • Steel and Composite Structures
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    • v.28 no.4
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    • pp.471-482
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    • 2018
  • The composite reinforced concrete and steel (RCS) structural systems have larger structural lateral stiffness, higher inherent structural damping, and faster construction speed than either traditional reinforcement concrete or steel structures. In this paper, four RCS subassemblies with or without the RC slab designed following a strong column-weak beam philosophy were constructed and tested under reversed-cyclic loading. Parameters including the width of slab and composite effect of the RC slab and beam were explored. The test results showed that all specimens performed in a ductile manner with plastic hinges formed in the beam ends near the column faces. The seismic responses of composite connections are influenced significantly by different width of slabs. Compared with that of the steel beam without the RC slab, it was found that the load carrying capacity of composite connections with the RC slab increased by 30% on average, and strength degradation, energy dissipation also had better performance, while the ductility of that were almost the same. Furthermore, the contribution of connection deformation to the overall specimen displacement was analyzed and compared. It decreased approximately 10% due to the coupling effect in the columns and beams with the RC slab. Based on the test result, some suggestions are presented for the design of composite RCS joints.

Seismic performance assessment of the precast concrete buildings using FEMA P-695 methodology

  • Adibi, Mahdi;Talebkhah, Roozbeh
    • Structural Engineering and Mechanics
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    • v.82 no.1
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    • pp.55-67
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    • 2022
  • The precast reinforced concrete frame system is a method for industrialization of construction. However, the seismic performance factor of this structural system is not explicitly clarified in some existing building codes. In this paper, the seismic performance factor for the existing precast concrete building frame systems with cast-in-situ reinforced shear walls were evaluated. Nonlinear behavior of the precast beam-column joints and cast-in-situ reinforced shear walls were considered in the modeling of the structures. The ATC-19's coefficient method was used for calculating the seismic performance factor and the FEMA P-695's approach was adopted for evaluating the accuracy of the computed seismic performance factor. The results showed that the over-strength factor varies from 2 to 2.63 and the seismic performance factor (R factor) varies from 5.1 to 8.95 concerning the height of the structure. Also, it was proved that all of the examined buildings have adequate safety against the collapse at the MCE level of earthquake, so the validity of R factors was confirmed. The obtained incremental dynamic analysis (IDA) results indicated that the minimum adjusted collapse margin ratio (ACMR) of the precast buildings representing the seismic vulnerability of the structures approximately equaled to 2.7, and pass the requirements of FEMA P-695.

Assessment of Fatigue Damage of Adhesively Bonded Composite -Metal Joints by Acousto-Ultrasonics and Acoustic Emission (음향초음파와 음향방출에 의한 복합재료-금속 접착접합부의 피로손상 평가)

  • Kwon, Oh-Yang;Lee, Kyung-Joo
    • Journal of the Korean Society for Nondestructive Testing
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    • v.21 no.4
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    • pp.425-433
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    • 2001
  • A correlation between fatigue damage and acousto-ultrasonic (AU) parameters has been obtained from signals acquired during fatigue loading of the single-lap joints of a carbon-fiber reinforced plastic (CFRP) laminates and A16061 plate. The correlation showed an analogy to those representing the stiffness reduction (E/E0) of polymer matrix composites by the accumulation of fatigue damage. This has been attributed to the transmission characteristics of acoustic wave energy through bonded joints with delamination-type defects and their influence on the change of spectral content of AU signals. Another correlation between fatigue cycles and the spectral magnitude of acoustic emission (AE) signals has also been found during the final stage of fatigue loading. Both AU and AE can be applied almost in real-time to monitor the evolution of damage during fatigue loading.

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Fabrication and Characteristics of HTS Field Winding of a 100 hp Synchronous Motor (100마력 동기전동기용 고온초전도 계자권선 제작과 특성)

  • Sohn Myung-Hwan;Baik Seung-Kyu;Lee Eon-Young;Kwon Young-Kil;Jo Young-Sik;Moon Tae-Sun;Kim Yeong-Chun;Kwon Woon-Sik
    • The Transactions of the Korean Institute of Electrical Engineers B
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    • v.54 no.2
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    • pp.88-93
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    • 2005
  • To develop a 100 hp high temperature superconducting(HTS) motor with high efficiency first in Korea, we fabricated a HTS field winding and test. HTS field winding is composed of sixteen HTS race track shaped coils wound with stainless steel-reinforced Bi-2223 tape conductor by react and wind fabrication method. Nomex paper was used for electrical insulation. Each of four magnet pole assemblies was constructed with four double pancake sub-coils, mechanically stacked and electrically in series. Four magnet assemblies were fixed on an aluminum support structure to make effective heat transfer. The Critical current (Ic) was 41.5A at 77K and self field. However the lowest Ic value of sub-coils was 35A. Joule heat generated by each joints between sub-coils was lower than 1mW at 77K and 34A. And Joule heat generated by the joints between field coils was lower than 10mW at 77K and 34A. Joule heat of the whole field winding was 1W at 77K and 32A. And so, the lowest Ic value of sub-coils was more important than Joule heats generated by all joints. The operating current must be lower than the lowest Ic of all the sub-coils. In this paper, design, construction and testing of HTS field winding, Joule heat generated by the joints, and operating current were discussed.