• Title/Summary/Keyword: Reinforced Concrete Member

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Global seismic performance of a new precast CFST column to RC beam braced frame: Shake table test and numerical study

  • Xu, S.Y.;Li, Z.L.;Liu, H.J.
    • Steel and Composite Structures
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    • v.21 no.4
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    • pp.805-827
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    • 2016
  • A new type of precast CFST column to RC beam braced frame is proposed in this paper. A series of shake table tests were conducted to excite a one-third scale six-story model for investigating the global seismic performance of this type of structure against earthquake actions. Particular emphasis was given to its dynamic property, global seismic responses and failure path. Correspondingly, a numerical model built on the basis of fiber-beam-element model, multi-layer shell model and element-deactivation method was developed to simulate the seismic performance of the prototype structure. Numerical results were compared with the measured values from shake table tests to verify the validity and reliability of the numerical model. The results demonstrated that the proposed novel precast CFST column to RC beam braced frame performs excellently under strong earthquake excitations; the "strong CFST column-weak RC beam" and "strong connection-weak member" anti-seismic design principles can be easily achieved; the maximum deflections of precast CFSTC-RCB braced frame satisfied the deflection limitations proposed in national code; the numerical model can properly simulate the dynamic property and responses of the precast CFSTC-RCB braced frame that are highly concerned in engineering practice.

Algorithm for the Reinforced Concrete Framework Materials Take-off (철근콘크리트조의 골조물량산출 알고리즘)

  • Kim Tae-Hui;Hong Chae-Gon;Kim Sun-Kuk
    • Korean Journal of Construction Engineering and Management
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    • v.4 no.1 s.13
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    • pp.114-121
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    • 2003
  • The precise quantity of materials is not yet taken off by the CAD system although it has Influenced in design productivity and automatic estimate. And various estimate systems developed so far deal with the quantity take-off of building members separately, which caused to over-estimate the part of each member. Therefore, the purpose of this paper is to develop algorithms of more precise estimate than that of current estimate by solving boundary conditions of the connection parts of building members, such as column, girder, beam, wall and slab. The algorithms are proposed to take off the quantity of concrete and form work and they will be used for the estimate of building structure more precisely and automatically than ever.

Dual potential capacity model for predicting failure of RC beams damaged by corrosion of tensile reinforcement

  • Sun-Jin Han;Deuckhang Lee;Hyo-Eun Joo;Kang Su Kim
    • Computers and Concrete
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    • v.34 no.4
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    • pp.503-517
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    • 2024
  • This study presents an analysis model to estimate the shear strength of a reinforced concrete (RC) member with corroded tensile reinforcements. The thick-walled cylinder theory was modified to fit the dual potential capacity model to reflect interdependent failure mechanisms, including the degradation effect of bonds in corroded tensile reinforcement. In the proposed model, it is considered that the shear failure of corroded RC members with no proper anchorage detail is primarily dominated by the flexural-bond mechanism, where insufficient bond strength is provided owing to corrosion damage. However, when tensile reinforcements are properly anchored in the end regions using end hooks or mechanical devices, it is assumed that the tied-arch action can be developed as a secondary shear transfer mechanism, even under severe corrosion damage. The proposed model was verified by comparison with shear test results of corroded RC members collected from the literature, and it appeared that the proposed model can estimate their shear strengths with a good level of accuracy, regardless of various anchorage details and corrosion rates in tensile reinforcements.

Connection rotation requirements on FRP-strengthened steel-concrete composite beam systems

  • Panagiotis M. Stylianidis;Michael F. Petrou
    • Structural Engineering and Mechanics
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    • v.92 no.2
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    • pp.133-147
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    • 2024
  • Composite beams of steel and concrete strengthened with fiber-reinforced polymers (FRP) may exhibit considerably enhanced flexural behaviour, but the combination of three materials with different characteristics and the various possible failure mechanisms that may govern performance make their analysis quite demanding. Previous studies provided significant insights into this problem and several methods were proposed for calculating flexural stiffness and strength, but these studies are restricted to the single member level of a simply supported composite beam section. However, the problem considerably changes when the beam is part of a frame system due to the degree of continuity provided by the surrounding structure, which represents the most common situation in practice. This paper explores the behaviour of semi-continuous FRP-strengthened composite beams, by considering the response characteristics of their end connections and their effects on overall performance. A novel analytical model is derived, which enables a step-by-step representation of the nonlinear relationship between an incremental mid-span design bending moment and corresponding connection rotations. After verification against finite element analyses, a parametric study is conducted which shows that the substantially increased bending moment resistance of FRP-strengthened composite beams can hardly be fully utilized due to a deficiency of corresponding large deformation capacity available in the connections. The extent to which the presence FRP strengthening can be exploited to enhance the beam flexural response depends on the interplay between various structural parameters, including the connection rotation capacity, the beam span, and the FRP modulus of elasticity and ultimate strength.

Influence of Tension Stiffening Effect on Deflection and Crack Width in RC Members (철근콘크리트 부재의 처짐과 균열폭에 대한 인장증강효과의 영향)

  • Choi, Seung-Won;Yang, Jun-Ho;Kim, Woo
    • Journal of the Korea Concrete Institute
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    • v.22 no.6
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    • pp.761-768
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    • 2010
  • When cracks occur in reinforced concrete structures, a steel carries all tensile force at crack section, while the concrete between cracks carries a part of the tensile force due to bond, so that the steel is less elongated. This is called the tension-stiffening effect, that plays an important role in verification of a serviceability limit state. But it is a complicated work to use a complex strain distribution between cracks, therefore an average strain is used to calculate deflection and crack width. In Eurocode 2, tension-stiffening effect expressed in the first order form or the second order form is used in calculating an average curvature for deflection. In this study for a flexural member deflection and crack width are calculated using various models for the tension-stiffening effect and the results are compared with the values of Eurocode 2 and KCI provisions. As results, the predicted values using the second order form are appeared to be well agreed with the experimental values and it could secure more analytical consistency.

Design Concept of Beams Reinforced by Deformed Bars and Non-Prestressed Strands in Combination (비긴장강연선과 철근이 혼용된 보의 설계방안)

  • Noh, Sam-Young;Jo, Min-Joo;Kim, Jong-Sung;Kim, Seung-Hun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.17 no.4
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    • pp.18-29
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    • 2013
  • A new precast concrete (PC) beam and column connection system using non-prestressed wire strands was recently developed. The system is composed of one unit of two-storied PC-column and PC-beams with U-shaped ends. The connection part of the column and beams is reinforced by deformed bars and non-prestressed wire strands in combination for the improvement of workability. Structural performance of this system was verified by several experimental studies. The purpose of this study is developing a design concept of the beam reinforced by deformed bars and non-prestressed wire strands in combination, in terms of the cross-sectional analysis, based on the preceded experiment. A minimum and maximum reinforcement ratio and the calculation formula for the strength of flexural member reinforced by reinforcements having different yield strengths are derived based on KBC2009. Under consideration existing research results for the application of high strength reinforcement bars, the design yield strength of the non-prestressed wire strand is suggested. An example for the cross section design, satisfying the serviceability requirements, demonstrates the applicability of the design concept developed in the study.

Secant Stiffness for Direct Inelastic Earthquake Design of Reinforced Concrete Structures (철근콘크리트 구조물의 직접비탄성 내진설계를 위한 할선강성)

  • Eom, Tae-Sung;Kim, Jae-Yo;Park, Hong-Gun
    • Journal of the Earthquake Engineering Society of Korea
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    • v.13 no.2
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    • pp.59-68
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    • 2009
  • For safe and economical design to provide strong earthquake resistance, the moment redistribution and plastic rotation of structures and their members needs to be evaluated. To achieve this, an earthquake design method was developed using secant stiffness analysis. To address the variation of member stiffness due to plastic rotation and moment redistribution, a structure was modeled with a beam-column element with non-rigid end connections (NREC element). Secant stiffness for the NREC element was determined based on the ductility demands of the structure and members. By performing a conventional linear analysis for the secant stiffness model, redistributed moments and plastic rotations of the members were computed. The proposed method was applied to a moment frame and two dual systems. The design results were verified using detailed nonlinear analyses.

Characteristics of Flexural Capacity and Ultrasonic in RC member with Corroded Steel and FRP Hybrid Bar (부식된 FRP Hybrid Bar의 휨 내력 및 초음파 속도 특성)

  • Choi, Se-Jin;Mun, Jin-Man;Park, Ki-Tae;Park, Cheol-Woo;Kwon, Seung-Jun
    • The Journal of the Korea Contents Association
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    • v.15 no.8
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    • pp.397-407
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    • 2015
  • Concrete is a attractive construction material, however durability problem occur due to steel corrosion, which leads propagation to structural safety problem. The recently developed FRP (Fiber Reinforced Plastic) Hybrid Bar has an engineering merit of both structural steel and FRP. Accelerated corrosion test for RC (Reinforced Concrete) samples with normal steel and FRP Hybriud Bar are performed and their flexural capacity is evaluated. Furthermore UV(Ultrasonic Velocity) measurement is attempted for analysis of variation of UV due to corrosion condition. After corrosion test, there is no significant reduction in RC beam with FRP hybrid bar but 11.5% of reduction in the case of normal steel is evaluated with 3.3% of UV reduction. For commercial production of FRP hybrid bar, bond strength evaluation through long-term submerged corrosion is required.

Study on the Cable Wall System Applied to Reinforced Concrete Exterior (철근콘크리트구조 외장재에 케이블월 시스템 적용에 관한 연구)

  • Park, Hyun-Sun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.3
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    • pp.579-585
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    • 2017
  • Development of a facade system that can reduce load factor and costs in high-rise building construction is required. The proposed cable wall system is used as a structural support by the glass-cable and can increase openness on lower elevations and the lobby area. Its use in high-rise buildings can reduce construction costs. Without transferring directly a strong initial tension of the cable to the building frame is connected to the steel member and the reinforced concrete structures, by absorbing the initial tension of the cable, it is possible to control the occurrence of a strong concentrated loads to the structure. Comparison of load-displacement test results from the numerical analysis with the test results showed reasonable agreement, Therefore, the proposed numerical results confirm good prediction of cable behavior for the facade system.

Optimum Design of Reinforced Concrete Plane Frames Based on Section Database (데이터베이스에 기반한 RC 평면 프레임 구조물의 최적설계)

  • Kwak, Hyo-Gyoung;Kim, Ji-Eun
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.20 no.2
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    • pp.165-179
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    • 2007
  • For the purpose of optimum design of reinforced concrete structures, pre-determined section database of column and beam are constructed and arranged in order of the resisting capacity. Then, regression equations representing the relation between section number and section resisting capacity are derived. In advance, effective optimization algorithms which search optimized solution quickly using direct search method from these database are proposed. In practice, from the fact that engineers conduct member design close to capacity optimization rather than cost optimization, both capacity and cost optimization using proposed algorithms are performed, and the review for the obtained results are followed. Moreover, the investigation for the applicability and effectiveness of the Introduced design procedure is conducted through correlation study for example structures. Because of no restriction in constructing objective functions with very simple optimization processes and fast convergence, the introduced method can effectively be used in the preliminary design stage. Especially, selected solutions from database are directly applicable in practice because these sections already satisfy all the requirements in design codes and practical restrictions.