• 제목/요약/키워드: Face-reinforced

검색결과 219건 처리시간 0.031초

반복하중을 받는 고강도 철근콘크리트 보-기둥 접합부의 구부림철근 효과에 관한 연구 (The Effects of Bent-up Bar on High Strength Reinforced Concrete Beam-Colum Joint Subjected to Cyclic Loads)

  • 신성우;이광수;오정근;권영호
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 1990년도 봄 학술발표회 논문집
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    • pp.61-65
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    • 1990
  • The purpose of this study was to investigate the effect of Bent-up Bars in Beam-Column Joint with High-Strength Concrete up to 800 kg/$\textrm{cm}^2$. 5 specimens were tested under reversed cyclic loadings. The primary variables were the number of the Bented Bars with Joint Core, compressive strength and loading patterrns. The results showed that bent-up bars in beam-column joint prevented crack from extending into core but the failure was concreterated at the face of beam-column joint. Thus shear stress constant value(Г) should be revised for High Strength Concrete Beam-Column Joint with Bent-up Bars.

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RC 건축물에 적용한 비탈형 영구거푸집의 경제성 평가에 관한 연구 (A Study On Economic Evaluation of Permancet Form For Reinforced Concrete Building)

  • 김형남;김우재;김성식;이복만;정상진
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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    • pp.475-480
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    • 1999
  • Recently domestic building market in the face of 3D, in addition to construction cost increase, materials lack problems and opening a building market to foreign countries, is trying to find out the efficient ways of overcoming these problems. So the necessity to study the permanent form is urgent to escape the problems of constructing human power economy, cost down, noises problem, environmental prevention and efficacy of form work to technical improvement will contribute a practical permanent form in field through economic evaluation of permanent form. In this paper, we compared wood form cost with permanent form cost(made form polymer or fly ash) for frame work

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Nonlinear finite element analysis of effective CFRP bonding length and strain distribution along concrete-CFRP interface

  • Dogan, Ali Baran;Anil, Ozgur
    • Computers and Concrete
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    • 제7권5호
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    • pp.437-453
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    • 2010
  • CFRP has been widely used for strengthening reinforced concrete members in last decade. The strain transfer mechanism from concrete face to CFRP is a key factor for rigidity, ductility, energy dissipation and failure modes of concrete members. For these reasons, determination of the effective CFRP bonding length is the most crucial step to achieve effective and economical strengthening. In this paper, generalizations are made on effective bonding length by increasing the amount of test data. For this purpose, ANSYS software is employed, and an experimentally verified nonlinear finite element model is prepared. Special contact elements are utilized along the concrete-CFRP strip interface for investigating stress distribution, load-displacement behavior, and effective bonding length. Then results are compared with the experimental results. The finite element model found consistent results with the experimental findings.

철근, 강판 및 CFRP를 적용한 R/C보의 보강효과 비교연구 (Comparative Study on the Strengthening Effect of R/C Beams with Rebar, Steel Plate of CFRP)

  • 심종성;황의승;최완철;배인환
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 1996년도 봄 학술발표회 논문집
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    • pp.323-327
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    • 1996
  • Reinforced concrete(R/C) structures need repair and rehabilitation due to the deterioration such as a crack, spalling and disintergration. Numerous repair materials which are currently used in construction fields without any regulation are examined in terms of their serviceabilities and effectiveness. In this paper section of existing R/C beams are enlarged with repair materials, that is, epoxy, latex or premix. And then they are strengthened with rebar, steel poate of CFRP on the tension face. Structural behaviors of strengthened beams are investigated both statically and dynamically and they are compared with each. This paper summarizes the overall research plan.

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3차원 유한요소해석에 의한 Umbrella Arch 공법으로 보강된 터널의 거동 해석 (Three-Dimensional Finite Element Analysis on Tunnel Behaivor Reinforced by Umbrella Arch Method)

  • 유충식;신승우
    • 한국지반공학회:학술대회논문집
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    • 한국지반공학회 1995년도 가을 학술발표회 논문집
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    • pp.211-216
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    • 1995
  • In recent years, Natm has been successfully applied to difficult ground conditions with the use of soil-perservention methods which promote face stability and restrict excessive ground movement. When the tunnle excavation od made through difficult ground like highly weathered rock, the umbrella arch method is often adopted which pre-reinforceas tunnel crown periphery using a stiff shell-shaped structure. The umbrella arch method was originally developed in Itali, and has recently been confirmed its effectiveness in Korea as well. However, no in depth study on the umbrella arch method has been conducted ans as a result no rational analysis/design method is available at present. Therefore this study was undertaken with the aim of identifying the basic reinforcing mechanism and satablishing both qualitative and quantiative relationships between various design parameters and ground movements.

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수평보강재로 보강된 터널 막장의 거동 (Behavior of Tunnel Face Reinforced with Horzontal Pipes)

  • 유충식;신현강
    • 자연, 터널 그리고 지하공간
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    • 제2권1호
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    • pp.130-138
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    • 2000
  • 본 연구에서는 수평보강재로 보강된 터널 막장의 거동에 관한 매개변수 연구결과를 다루었다. 매개변수 연구에서는 막장주변의 3차원 응력-변형율 거동을 보다 효율적으로 모델링하기 위해 3차원 유한요소해석 모형을 적용하였으며 보강패턴에 따른 막장의 거동을 고찰하기 위해 다양한 경계조건에 대한 해석을 수행하였다. 해석결과를 토대로 막장의 응력해방-변위거동의 관계를 고찰하였으며, 보강패턴과 막장 변위의 정성${\cdot}$정량적인 관계를 제시함과 아울러서 향후 수행될 반경험적 설계/해석법의 개발을 위한 데이터베이스를 구축하였다. 한편, 해석결과 보강재 타설수 및 길이 등 각 보강설계 인자에 대한 임계치가 존재하는 것으로 나타났으며 따라서 보다 안전하고 경제적인 설계를 위해서는 이를 고려하여야 할 것으로 판단된다.

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Flexural Behavior of RC Beams Strengthened with Steel Plates/Carbon Fiber Sheets(CFS) under Pre-Loading Conditions

  • Shin, Yeong-Soo;Hong, Geon-Ho
    • KCI Concrete Journal
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    • 제12권1호
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    • pp.69-77
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    • 2000
  • The reinforced concrete(RC) flexural members strengthened with steel plate/CFS at soffit have initial stresses and strains in reinforcements and concrete caused by the service loads at the time of retrofitting works. These initial residual stresses and strains of strengthened beams may affect the flexural performance of the rehabilitated beams. The objective of this study is to evaluate and verify the effectiveness of rehabilitation by external bonded steel plates and CFS to the tension face of the beams under three conditions of pre-loading. Thirteen beam specimens are tested and analyzed. Main test parameters are pre-loading conditions, strengthening materials and reinforcement ratio of specimens. The effect of test parameters on the strengthened beams is analyzed from the maximum load capacity, load-deflection relationship, state of stress of the materials. crack propagation phase, and failure modes. Both test results and design formulas of ACI Code provisions are compared and evaluated.

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Nonlinear dynamic characteristic of sandwich graphene platelet reinforced plates with square honeycomb core

  • Mamoon A.A. Al-Jaafari;Ridha A. Ahmed;Raad M. Fenjan;Nadhim M. Faleh
    • Steel and Composite Structures
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    • 제46권5호
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    • pp.659-667
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    • 2023
  • Nonlinear forced vibration behaviors of sandwich plates having graphene platelets (GPL) based face sheets have been researched in this article. Possessing low weight together with low stiffness, square honeycomb cores are mostly constructed by aluminum. Herein, the square shaped core has been fortified by two skins of GPL-based type in such a way that the skins have uniform and linearly graded GPL dispersions. The square shaped core has the effective material specification according to the relative density concept. The whole formulation has been represented based upon classical plate theory (CPT) while harmonic balance approach is applied for solving the problem and plotting the amplitude-frequency curves. The forced vibration behaviors of such plates are influenced by square-shaped core and the relative density, skin's height and GPL fortification.

Using nano-micro-control technology to improve breathing pressure in vocal music technique teaching innovation

  • Jiayue Cui;Hongliang Zhang
    • Advances in nano research
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    • 제15권3호
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    • pp.239-251
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    • 2023
  • In the present study, we aim to use nanotechnology sensors/actuators to capture pressure and frequency of voice singers and to send signals for improving breathing pressure. In this regard, a circular composite structure having 3 different layers are used. The core layer is nano-composite material reinforced with graphene nanoplatelets. The face sheets are piezo electric materials connected to electrical circuit capable of measuring and applying voltage to the piezoelectric layers. This sensors have extremely smaller size than conventional sensors attached to the neck of singer and, hence, minimizes the influences on the output voice of the singer. A brief theoretical framework are presented for nonlocal strain gradient theory and geometry of the sensor is described in detail. The controlling procedure along with experimental results on 20 amateur and professional singer participants are also presented. The results of the study indicate that the participants could gain benefit from the device for improving their ability in phonation and keeping their frequency at a constant level although they have difficulty in the beginning of the experiment getting used to the device.

Theoretical analysis of stress-strain behavior of multi-layer RC beams under flexure

  • Ertekin Oztekin
    • Structural Engineering and Mechanics
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    • 제90권5호
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    • pp.505-515
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    • 2024
  • In this study, obtaining theoretical stress-strain curves and determining the parameters defining the equivalent rectangular stress block were aimed for 3 and 4-layered rectangular Reinforced Concrete (RC) cross-sections subjected to flexure. For these aims, the analytical stress-strain model proposed by Hognestad was chosen for the concrete grades (20 MPa≤fck≤60 MPa) used in this study. The tensile strength of the concrete was neglected and the thickness of the concrete layers in the compression zone of the concrete cross-section was taken as equal. In addition, while concrete strength was kept constant within each layer, concrete strengths belonging to separate layers were increased from the neutral axis towards the outer face of the compression zone of the concrete cross-section. After the equivalent rectangular stress block parameters were determined by numerical iterations, variations of these parameters depending on concrete strength in layers and layer numbers were obtained. Finally, some analytical equations have been proposed to predict the equivalent stress block parameters for the 3 and 4-layered RC cross-sections and validities of these proposed equations were shown by different metrics in this study.