• Title/Summary/Keyword: Confined

검색결과 2,268건 처리시간 0.036초

결합재의 종류 및 치환율에 따른 구속수비의 특성에 관한 연구 (A Study on the Properties of the Confined water ratio for Binder type and Replacement ratio)

  • 권영호;이현호;이화진;하재담
    • 한국콘크리트학회:학술대회논문집
    • /
    • 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
    • /
    • pp.584-587
    • /
    • 2004
  • This research investigates the rheological behavior and the confined water ratio of the cement paste and binder condition in order to predict mix design proportion of the high flowing concrete. The purpose of this study is to determine the optimum replacement ratio of binders including fly ash, and lime stone powder by the cement weight. For this purpose, belite cement, blast furnace slag cement and ordinary portland cement are selected. As test results, the confined water ratio shows the following range ; OPC>blast furnace slag cement>belite cement. Therefore, belite cement is proved very excellent cementitious materials in a view point of the flowability. The optimum replacement ratio of lime stone powder is shown over $30\%$ in case of belite cement and about $10\%$ in case of slag cement type. Also, the optimum replacement ratio of fly ash is shown $30\%$ by the cement weight considering the confined water ratio and deformable coefficient of the paste condition.

  • PDF

3차원 거동에 의한 원형 FRP-구속 콘크리트의 부재 비선형 모델 (Nonlinear Model of FRP-Confined Concrete Members Considering with Three-Dimensional Behaviors)

  • 조창근;권민호;박문호;김화중;배수호
    • 한국콘크리트학회:학술대회논문집
    • /
    • 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
    • /
    • pp.738-741
    • /
    • 2004
  • This study is concerning on modeling to predict the flexural behaviors of FRP-confined concrete structural members. For compressive behaviors of confined concrete by FRP jackets, the hypoelasticity-based constitutive law of concrete has been presented under the basis of three-dimensional stress states. The strength enhancement of concrete wrapped by FRP jackets has been determined by the failure surface of concrete in tri-axial states, and its corresponding peak strain is computed by the strain enhancement factor. The behavior of FRP jackets has been modeled using the mechanics of orthotropic laminated composite materials in two-dimensional stress states. To be based on the three-dimensional constitutive laws, an algorithm for the prediction of flexural bending behaviors of FRP-confined concrete structural member has been presented.

  • PDF

복합재료에 의하여 구속된 콘크리트의 응력-변형률 곡선 예측 (Stress-Strain Curve of Concrete Confined with both Steel Ties and FRP Composites)

  • 이정윤;황현복;오영준
    • 한국콘크리트학회:학술대회논문집
    • /
    • 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
    • /
    • pp.64-67
    • /
    • 2004
  • In recent years, the use of FRP composites to repair and strengthen existing reinforced concrete (RC) structures has been widely used. When the columns of existing RC structures are wrapped with FRP composites, the core concrete of such columns is confined not only by the FRP composites but also by the existing steel reinforcing ties (or spirals). Therefore, it is necessary to understand correctly the compressive response of concrete confined with both steel spirals and FRP composites in order to predict the behavior of such RC columns. This paper proposes a model to predict the compressive stress-strain curves of concrete confined with FRP and steel reinforcing ties.

  • PDF

화염배출 출구면적 변화에 대한 수직발사관 내부 초음속 충돌유동의 수치적 해석 (NUMERICAL INVESTIGATIONS OF SUPERSONIC JET IMPINGEMENT ON A FLAT WALL IN A CONFINED PLENUM)

  • 이광섭;홍승규;안창수
    • 한국전산유체공학회:학술대회논문집
    • /
    • 한국전산유체공학회 2005년도 추계 학술대회논문집
    • /
    • pp.281-285
    • /
    • 2005
  • Viscous solutions of supersonic jet impinging on a flat wall in a confined plenum are simulated using three-dimensional Navier-Stokes solver. A confined plenum was designed for simulating the missile launch and analyzing the behavior of the exhaust plume, which were accompanied by complex flow interactions with shock and boundary layer. Concerns of this paper are to show accurate simulation of internal flow in confined plenum and to demonstrate the jet flow structure when the jet interacts with a small opening on the side. Objectives of this numerical simulation are to understand the effect of changing the plume exit area of the plenum. Pressure and temperature rise at certain position in the plenum are traced and compared with test data.

  • PDF

구속신장시험에 의한 토목섬유의 인장력-변형률거동 특성 (Stress-Strain Properties of Geosynthetics by Confined Extension Tests)

  • 방윤경;전영근;이준대
    • 한국안전학회지
    • /
    • 제17권2호
    • /
    • pp.52-57
    • /
    • 2002
  • In this study. stress-strain relationships were investigated by performing the confined extension tests for seven types of geosynthetics such as geotextiles, composite geosynthetics and geogrids. A comparison was made between unconfined and confined moduli for each geosynthetic material to quantify the soil confinement effect on stress-strain properties. A comparison was also made between the increase of moduli at the same strain level with the types of the geosynthetics to demonstrate the different stress-strain responses. Based on the result of the extension tests, the higher the confining stress, the larger the secant modulus of geosynthetics. The secant modulus at 5% strain is twice as much as that of 10% strain, especially there is a noticeable increasing of secant modulus for the two nonwoven geotextiles.

Experimental study on reinforced high-strength concrete short columns confined with AFRP sheets

  • Wu, Han-Liang;Wang, Yuan-Feng
    • Steel and Composite Structures
    • /
    • 제10권6호
    • /
    • pp.501-516
    • /
    • 2010
  • This paper is aiming to study the performances of reinforced high-strength concrete (HSC) short columns confined with aramid fibre-reinforced polymer (AFRP) sheets. An experimental program, which involved 45 confined columns and nine unconfined columns, was carried out in this study. All the columns were circular in cross section and tested under axial compressive load. The considered parameters included the concrete strength, amount of AFRP layers, and ratio of hoop reinforcements. Based on the experimental results, a prediction model for the axial stress-strain curves of the confined columns was proposed. It was observed from the experiment that there was a great increment in the compressive strength of the columns when the amount of AFRP layers increases, similar as the ultimate strain. However, these increments were reduced as the concrete strength increasing. Comparisons with other existing prediction models present that the proposed model can provide more accurate predictions.

전단스팬비 영향을 고려한 RC구속조적조 벽체의 내진성능평가 (Seismic Performance Evaluation of Confined Masonry Wall System Considering of Shear-Depth Ratio)

  • 김경태;서수연;윤승조;성기태
    • 한국콘크리트학회:학술대회논문집
    • /
    • 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
    • /
    • pp.1-4
    • /
    • 2005
  • To investigate the effective seismic strengthening methods for masonry walls in developing countries, a total of four confined masonry (CM) walls were constructed and tested. In order to investigate the effect of the height of application point of lateral loads and reinforcing steel bars in walls and columns for the improvement of the seismic behavior of confined concrete block masonry walls, an experimental research program is conducted. The heights of inflection point considered were 0.67 and 1.11 times the height of the wall measured from the top of foundation beam. The constant vertical axial stress applied was 0 MPa. During the test, cracking patterns, load-deflection data, and strains in reinforcement and walls in critical locations was measured. From test data, it was showed that the seismic performance of confined concrete block masonry walls was significantly affected by test variables.

  • PDF

초고강도 철근콘크리트 띠철근 기둥의 구속효과 (Confined Effect of Ultra High Strength Reinforced Concrete Tied Columns)

  • 한범석;신성우;김태수
    • KIEAE Journal
    • /
    • 제7권4호
    • /
    • pp.105-111
    • /
    • 2007
  • As this study investigates the influence about type of transverse reinforcement, spacing of transverse reinforcement(s), volumetric ratios of transverse reinforcement(${\rho}s$) of ultra-high strength concrete columns. It try to offer to resonable basic data of the confined model for the ultra-high concrete of in reinforced concrete columns. Experimental tests with large scaled columns were conducted under concentric axial loads. The ultra-high strength concrete (100MPa) was used. From this test result, it evaluate influence of the strength enhancement and ductility enhancement, important variables about behavior of the confined concrete by confinement of ultra-high strength reinforced concrete.There are two ways to improve the confinement effect of high strength concrete columns through the increase of amounts and/or strength of transverse reinforcement.

파형강관으로 내부구속된 중공 R.C 교각의 연성도 (Ductility Characteristics of a Hollow R.C Pier Internally Confined by a Corrugated Steel Tube)

  • 한택희;김성남;강영종;정두석
    • 한국철도학회:학술대회논문집
    • /
    • 한국철도학회 2005년도 춘계학술대회 논문집
    • /
    • pp.712-717
    • /
    • 2005
  • When the weight if a concrete member makes problems, or when the cost of the concrete is relatively high, it may be economical to use a hollow concrete member. But a hollow R.C column may have poor ductility because of the brittle failure at the inner face of the hollow R.C column. This brittle failure results from the absence of the confinement at the inner face of the hollow R.C column. To avoid this brittle failure an internally confined hollow R.C column by a steel tube was developed before. In this study, a hollow R.C column is internally confined by a corrugated steel tube instead of a general flat steel tube. And a column ductility is performed. Test results show that the energy ductility ratio of a internally confined hollow R.C column by a by a corrugated steel tube corresponds to $80\%$ of the energy ductility ratio of a general solid R.C column.

  • PDF

용접 띠철근으로 보강된 철근콘크리트 기둥의 강도와 연성(II) - 보편적인 띠철근 보강 기둥과의 비교를 중심으로 (Strength and Ductility of R/C Columns with Welded Reinforcement Grids(II) - Focused on Comparisons with Columns Confined by Conventional Reinforcement)

  • 최상식
    • 한국콘크리트학회:학술대회논문집
    • /
    • 한국콘크리트학회 1997년도 가을 학술발표회 논문집
    • /
    • pp.561-568
    • /
    • 1997
  • Conventional confinement reinforcement for rectangular columns consist of closely spaced perimeter hoops, overlapping hoops, and crossties. One of the potential alternatives to conventional reinforcement is a welded reinforcement grid, prefabricated to required size and volumetric ratio of transverse reinforcement. An experimental investigation was carried out to investigate the strength and deformability of reinforced concrete columns confined with welded reinforcement grids. The comparisons of the envelopes of experimental force-displacement hysteric relationships for columns confined by welded grids with analytically generated force-displacement curves for columns confined with conventional ties. In general, inelastic deformability beyond the peak, as indicate by the slope of the cuvers, was similar to those indicated by columns with conventional ties. The superior performance of columns with welded grids may be attributed to the improved confinement characteristics of grids associated with increased rigidity of welded ties.

  • PDF