• Title/Summary/Keyword: 횡구속

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Confinement Range of Transverse Reinforcements for T-shaped Reinforced Concrete Walls (철근콘크리트 T형 벽체의 콘크리트 구속을 위한 횡철근의 배근범위)

  • 하상수;오영훈;최창식;이리형
    • Journal of the Korea Concrete Institute
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    • v.14 no.6
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    • pp.1001-1009
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    • 2002
  • The objective of this study is to determine the range of confinement (or the transverse reinforcement of the reinforced concrete structural walls with the T-shaped cross section subjected to cyclic lateral loads. The range of confinement for transverse reinforcement is related to the location of neutral axis and determined by the magnitude and distribution of compressive strain. The compressive strain depends on the ratio of wall cross sectional area to the floor-plan area, the aspect ratio, configuration, the axial load, and the reinforcement ratios. By affection of flange, the neutral axis appears different depending on positive and negative forces and because of this reason, when web and flange are subjected to compressive stress, the range of confinement for the transverse reinforcement of T-shaped walls would shows different result. Therefore this experimental research focused on the structural characteristics of T-shaped walls and suggested the neutral axis depth through comparing the results of this study with sectional analysis.

Strength Characteristics of Square Concrete Column Confined by Carbon Composite Tube (탄소섬유튜브로 횡구속된 각형 콘크리트 기둥의 압축강도 성능에 관한 연구)

  • 홍원기;김희철;윤석한;박순섭
    • Journal of the Earthquake Engineering Society of Korea
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    • v.7 no.1
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    • pp.1-7
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    • 2003
  • The carbon composite tube can play an important role in replacing or complementing longitudinal and transverse reinforcing steels by providing ductility and strength for conventional columns. In this study, both the experimental and analytical investigations of axial behavior of large-scale square concrete columns confined by carbon composite tube are presented. The specimens are filament-wound carbon composite with 90$^{\circ}$+30$^{\circ}$, 90$^{\circ}$+45$^{\circ}$ winding angle respect to longitudinal axis of tube. The instrumented large-scale concrete-filled composite tubes(CFCT) are subjected to monotonic axial loads exerted by 10,000kN UTM. The influence of winding angle, thickness of tube on stress-strain relationships of the confined columns is identified and discussed. Proposed equations to predict both the strength and ductility of confined columns by carbon composite tube demonstrate good correlation with test data obtained from large-scale specimens.

Effect of High Temperature on Mechanical Properties of Confined Concrete with Lateral Reinforcement (고온을 받은 횡방향 철근 구속 콘크리트의 역학적 특성 연구)

  • Choi, Kwang Ho;Lee, Joong Won
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.16 no.1
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    • pp.131-139
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    • 2012
  • The lateral reinforcements of concrete such as hoops and spiral bars are known to confine concrete to compensate the strength loss due to fire by reducing explosive spalling and improving the capacity of ductility. In this context, a study was conducted to investigate the residual mechanical properties of confined and unconfined concrete($f_{ck}$=60MPa) after a single thermal cycle at 300, 600, $800^{\circ}C$. The main parameters required to establish the stress-strain relationship are the peak stress, the elastic modulus, and the strain at peak stress. The knowledge of the residual mechanical properties of concrete is necessary whenever the thermally damaged structure is required to bear a significant share of the loads, even after a severe thermal accident. Based on the results obtained in this study, the residual stress of confined concrete under thermal damage is higher according to the level of confinement and the larger strain made it to have better ductility. The decreasing ratio of elastic modulus from the relationship of stress and strain was also smaller than that of unconfined concrete.

A Nonlinear Material Model for Concrete Compression Strength Considering Confining Effect (30-40Mpa의 압축강도를 갖는 콘크리트의 구속효과를 고려한 비선형 재료모델의 적용성 검토)

  • Lee, Heon-Min;Park, Jae-Guen;Hwang, Jae-Min;Yun, Hee-Tack;Shin, Hyun-Mock
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2009.04a
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    • pp.379-382
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    • 2009
  • 횡방향으로 구속된 콘크리트의 응력-변형률 거동은 구속되지 않은 콘크리트와는 다른 거동을 한다. 보통강도 콘크리트에서 구속효과를 고려한 콘크리트 재료모델로는 Mander 모델이 대표적이며 고강도 콘크리트의 구속효과의 경우 여러 연구자들에 의하여 제안된 모델 중 공시체 수준의 실험결과와 잘 일치하는 Sakino-Sun 모델을 사용하였다. 보통강도에서는 Mander모델을 고강도 콘크리트에서는 Sakino-Sun 모델을 사용하였으나 중간 강도인 30-40MPa의 강도에서 Mander 모델과 Sakino-Sun 모델의 적용시 실험결과와 해석결과가 다소 차이를 보이며 또한 두 모델은 적용할 수 있는 최대 또는 최소 콘크리트 압축강도의 한계범위가 명확하지 않다. 따라서 이 연구에서는 30-40MPa의 강도의 횡방향으로 구속된 콘크리트의 비선형 재료모델을 제안하고 실제 30-40MPa의 압축강도를 갖는 콘크리트 공시체의 일축압축시험 결과와의 비교를 통해 그 적용성을 검토하였다.

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Stress-strain Model of Laterally Confined High-strength Concrete with the Compressive Fracture Energy (압축파괴에너지를 도입한 횡구속 고강도 콘크리트의 응력-변형률 모델)

  • Hong, Ki-Nam;Shim, Won-Bo
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.23 no.1
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    • pp.54-62
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    • 2019
  • In this paper, a stress-strain model for high-strength confined concrete is proposed using compressive fracture energy. In the compression test performed by author in Reference [6], an acrylic bar with strain gauges was embedded in the center of the specimen to measure the local strain distribution. It was found from the test that the local strain measurement by this acrylic rod is very effective. The local fracture zone length was defined based on the local strain distribution measured by the acrylic rod. Specifically, it was defined as the length where the local strain increases more than twice of the strain corresponding to maximum stress. In addition, the stress-strain relationship of confined concrete with compressive fracture energy is proposed on the assumption that the amount of energy absorbed by the compressive members subjected to the given lateral confining pressure is constant regardless of the aspect ratio and size. The proposed model predicts even results from other researchers accurately.

Seismic Performance of RC Columns Confined by Outside Lateral Reinforcement (외측 횡보강재로 구속된 철근콘크리트 기둥의 내진성능)

  • Lee, Do Hyung;Oh, Jangkyun;Yu, Wan Dong;Choi, Eunsoo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.32 no.3A
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    • pp.189-196
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    • 2012
  • In this paper, reinforced concrete columns test has been conducted under repeated lateral load reversals. The test columns have been reinforced with outside lateral confinement members in addition to transverse reinforcements. For this purpose, a strainless steel and a GFRP have been employed for the lateral confinement members. Primary parameters are types, thickness and spacing of the lateral confinement members. Experimental results reveal that columns reinforced with lateral confinement members exhibit improved ductility and energy dissipation capacity in comparison with those unreinforced. It is thus concluded that the present approach can be of a useful scheme for the seismic retrofitting of reinforced concrete columns.

Transverse Reinforcement for Circular Internally Confined Hollow RC column (원형 내부 구속 중공 RC 기둥의 심부 구속 횡방향 철근 연구)

  • Won, Deok Hee;Han, Taek Hee;Park, Woo Sun;Park, Jong Sub;Kang, Young Jong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.2
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    • pp.927-935
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    • 2013
  • Recently, bridge structures has progressed the researches about seismic performance by occurrence of earthquake increased compared with the past. In the substructure of bridge, confining transverse reinforcement has arranged in plastic hinge region to resist the lateral load which increased the lateral confining effect. Columns are increased the seismic performance through secure of the stiffness and ductility The design specification for arrangement of confining transverse reinforcement same specification of domestic and international that suggested to solid reinforced concrete column(RC). This design specification have limits for Internally Confined Hollow RC(ICH RC) column because of different the component and performance characteristics of column. In this paper suggested the modified equation for economics and rational design through investigation of displacement ductility when applied the existing specification at the steel composite hollow RC column.

Experimental Study on Behavior of Confined Concrete with Electric Arc Furnace Oxidizing Slag Aggregates (전기로 산화 슬래그 골재를 사용한 콘크리트의 횡 구속 거동에 관한 실험적 연구)

  • Kim, Sang-Woo;Lee, Jung-Mi;Lee, Yong-Jun;Jung, You-Jin;Kim, Kil-Hee
    • Journal of the Korea Concrete Institute
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    • v.23 no.2
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    • pp.195-201
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    • 2011
  • This paper estimates the structural performance of spirally confined concrete having electric arc furnace (EAF) oxidizing slag aggregates. The EAF oxidizing slag is a by-product generated from iron and steel industry. The EAF oxidizing slag have been largely put to low-value-added uses due to its expansive properties of the free-CaO and free-MgO. Recently, this problem has been solved by the advances in steelmaking technology and thereby stabilizing EAF oxidizing slag aggregate. To verify the application of the EAF oxidizing slag aggregate to the structural concrete usage, a total of 27 cylindrical specimens with a diameter of 150 mm and a height of 300 mm were cast and tested. The test parameters were aggregate type and spiral reinforcement yield strength. Experimental results showed that the structural performance of specimens with EAF oxidizing slag aggregates was equivalent to that of confined concrete with natural aggregates.

An Experimental Study on Uniaxial Compressive Behavior of RC Circular Columns Laterally Confined with Prestressing Aramid Fiber Strap (아라미드 스트랩으로 프리스트레싱 횡구속된 RC 원형기둥의 일축압축거동에 관한 실험적 연구)

  • Han, Sang-Hoon;Hong, Ki-Nam;Lee, Jae-Bum
    • Journal of the Korea Concrete Institute
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    • v.21 no.2
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    • pp.159-168
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    • 2009
  • In this study, strength, stiffness and confinement effect with stress-strain and stress-volumetric strain curves for improved uniaxial compressive behavior of RC circular columns laterally confined with prestressing aramid fiber strap were experimentally investigated. The test variables were the specimens with or without axial reinforcing bar and the number and spacing of strap, prestressing level, the types of reinforcing fiber (CFS, GFS). As a result, the failure type of the columns was very stable and strength increase rate was about 73% comparison with the general RC columns. Moreover, the strain increase rate is very small and the axial displacement confinement effect was very effective compared with existry methods (CFS, GFS), the initial and final lateral confinement effect was excellent.

Seismic Performance of Octagonal Flared RC Columns using Oblong Hoops (장방형 띠철근을 이용한 팔각형 플레어 RC 기둥의 내진성능)

  • Ko, Seong-Hyun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.19 no.6
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    • pp.1-9
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    • 2015
  • Transverse steel bars are used in the plastic hinge zone of columns to insure adequate confinement, prevention of longitudinal bar buckling and ductile behavior. Fabrication and placement of rectangular hoops and cross-ties in columns are difficult to construct. Details of reinforcement for rectangular section require a lot of rectangular hoops and cross-ties. In this paper, to solve these problems, the new lateral confinement method using oblong hoop is proposed for the transverse confinement of the flared column. It can be the alternative for oblong cross-section and flared column with improved workability and cost-efficiency. The final objectives of this study are to suggest appropriate oblong hoop details and to provide quantitative reference data and tendency for seismic performance or damage assessment based on the drift levels such as residual deformation, elastic strain energy. This paper describes factors of seismic performance such as ultimate displacement/drift ratio, displacement ductility, response modification factor, equivalent viscous damping ratio and effective stiffness.