• Title/Summary/Keyword: Without Reinforcement

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Effects of Three-Week Contract-Relax Interventions with and without Reinforcement Using Temporal Summation for Flexibility and Balance Ability in Young People with Hamstring Shortening (공간적 가중을 이용한 강화 유무에 따른 3주간 수축-이완 중재가 넙다리뒤근 단축 대상자의 유연성과 균형능력에 미치는 효과)

  • Kim, Yong-Hun;Park, Du-Jin
    • PNF and Movement
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    • v.20 no.3
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    • pp.383-390
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    • 2022
  • Purpose: The purpose of this study was to examine the effect of three-week contract-and-relax (CR) interventions with and without reinforcement using temporal summation for flexibility and dynamic balance ability in young people with hamstring shortening. Methods: This study was conducted on 20 female college students with hamstring shortening. The participants were divided equally into two groups using stratified randomization: the CR group (CRG) and the CR with reinforcement group (CRRG). All interventions were applied three times a week for three weeks. The passive straight leg raise (PSLR) test and functional reaching test (FRT) were conducted on each participant before and after the three-week intervention. Results: In both groups, PSLR and FRT improved significantly after the three-week intervention compared to before intervention (p < 0.01). The amount of change in PSLR after the three-week intervention was significantly higher in CRRG than in CRG (p < 0.05). Conclusion: Three-week CR interventions with and without reinforcement were effective in improving PSLR and FRT. To improve hamstring shortening, CR intervention with reinforcement may be more useful than CR intervention without reinforcement.

A Study on the Mechanical Characteristics of a Structure Reinforced by Cylindrical Reinforcement with Fins (핀을 가진 원통형 보강재로 보강된 구조물의 기계적 특성에 관한 연구)

  • 김형준;박정호;김현수;조우석
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2002.10a
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    • pp.804-807
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    • 2002
  • In general, the reinforcement of a structure is performed with cylinders. In this study, it is attempted to analyze the circular reinforcement with fins. And the maximum stress and deflection is investigated fur the circular reinforcement between two plates. The shape of models are : one which has only circular reinforcements of different diameters and one which has circular reinforcements with fins and one which has fin of same length and circular cylinders of different diameters. And in each model, there are two kinds; one is with upper and lower plates and the other with none. The results shows that the maximum stress is less in the model of circular reinforcement with fins than that in the model without fins. And the maximum stress of a model without upper and lower plate is less than that of a model with plates.

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A Study on the Design Formula about Strengthening in Flexure with Steel Plate in Reinforced Concrete Beams (철근콘크리트 보의 강판 휨보강 설계식에 관한 연구)

  • Kim, Jong-Ok;Jang, Hwa-Kyun;Won, Young-Sul;Joo, Kyung-Jai
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.4 no.4
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    • pp.121-128
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    • 2000
  • When RC beams are strengthening in flexure with steel plate, they have initial strain due to dead load. Strain of steel used in strengthening member is zero. The effect of strengthening in flexure at member changes in accordance with the quantity of initial strain. But in most cases, Quantity of reinforcement is determined without regard to the difference of initial strain when there are calculated the strengthening in flexure at beams. Such method is possible to suggest inadequate quantity of reinforcement. Thus, the object of the study is to suggest practical design equation and reinforcement proposal using comparison and analysis reinforcement efficiency about fexural strength in case with regard and without regard to the initial strain when Re beams are strengthening in flexure with steel plate.

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Evaluation of Shear Performance of Reinforced Concrete Beams for Varying Reinforcement Details of Web Opening (유공부 보강상세에 따른 철근콘크리트 유공 보의 전단 성능 평가)

  • Kim, Min-Jun;Lee, Bum-Sik;Kim, Dong-Whan;Kim, Hyeong-Gook;Lee, Yong-Jun;Kim, Kil-Hee
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.22 no.4
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    • pp.19-26
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    • 2018
  • This study evaluates the shear performance of reinforced concrete members with web opening reinforcement. A total of 4 reinforced concrete members with or without openings were cast then tested. The main variables investigated were with or without of web openings and with or without of web opening reinforcement, respectively. The proposed web opening reinforcement was a rectangle and rhombus-shaped spiral considering of construct ability. Test result showed that the proposed web reinforcement had improved shear capacity and ductility of the specimens. It was found that the web opening reinforcement proposed in this study had a positive effect on the shear strength and crack control of RC beams with web openings. In addition, it was confirmed that the analytical results by the current design codes underestimates the test results of the specimens with the proposed web opening reinforcement.

Failure Mechanism of Headed Reinforcement including Bond Failure (부착파괴를 고려한 Headed Reinforcement의 파괴메카니즘)

  • 박종욱;홍성걸
    • Proceedings of the Korea Concrete Institute Conference
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    • 2003.11a
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    • pp.234-237
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    • 2003
  • Previous researches about headed reinforcement have not been concerned about bond failure which is quite important is some cases. In this paper, failure mechanism including bond failure was presented in order to define the contribution of bond stress at the time failure occurs. Examined with design codes and test results, it is proved to be rational to consider the contribution of bond stress in determining the ultimate pull-out capacity of headed reinforcement. Direct adaptation of design code for anchor bolt without modification for the contribution of bond stress will lead to underestimate the capacity of headed reinforcement.

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Behaviour of RC Beams with non-bonded flexural reinforcement: A numerical experiment

  • Kotsovou, Gregoria M.;Kotsovos, Gerasimos M.
    • Computers and Concrete
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    • v.18 no.2
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    • pp.165-178
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    • 2016
  • The present work is concerned with a numerical investigation of the behaviour of reinforced-concrete beams with non-bonded flexural tension reinforcement. The numerically-established behaviour of such beams with and without transverse reinforcement is compared with its counterpart of similar beams with bonded reinforcement. From the comparison, it is found that the development of bond anywhere within the shear span inevitably leads to inclined cracking which is the cause of 'shear' failure. On the other hand, the lack of bond within the shear span of the beams is found, not only to prevent cracking within the shear span, but, also, to lead to a flexural type of failure preceded by the formation of horizontal splitting of concrete in the compressive zone. It is also found that delaying the extension of horizontal splitting through the provision of transverse reinforcement in the beam mid span can lead to flexural failure after yielding of the tension reinforcement. Yielding of the tension reinforcement before the horizontal splitting of the compressive zone may also be achieved by reducing the amount of the latter reinforcement.

Load-Displacement Formulations of Low-rise Unbounded RC Shear Walls with or without Openings

  • Lou, K. Y.;Cheng, F. Y.;Sheu, M. S.;Zhang, X. Z.
    • Computational Structural Engineering : An International Journal
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    • v.1 no.2
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    • pp.117-130
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    • 2001
  • Investigations of low-rice unbounded reinforced concrete shear walls with or without openings are performed with comparison of analytical and experimental results. Theoretical analysis is based on nonlinear finite element algorithm, which incorporates concrete failure criterion and nonlinear constitutive relationships. Studios focus on the effects of height-to-length ratio of shear walls, opening ratio, horizontal and vertical reinforcement radios, and diagonal reinforcement. Analytical solutions conform well with experimental results. Equations for cracking, yielding and ultimate loads with corresponding lateral displacements are derived by regression using analytical results and experimental data. Also, failure modes of low-rise unbounded shear walls are theoretically investigated. An explanation of change in failure mode is ascertained by comparing analytical results and ACI code equations. Shear-flexural failure can be obtained with additional flexural reinforcement to increase a wall's capacity. This concept leads to a design method of reducing flexural reinforcement in low-rise bounded solid shear wall's. Avoidance of shear failure as well as less reinforcement congestion leer these walls is expected.

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Shear Behavior of High-Strength Steel Reinforced Concrete Beams without Stirrups (고장력 주인장 철근을 사용한 전단보강이 없는 보의 전단성능에 관한 연구)

  • Shon, Young-Moo;Yoon, Young-Soo
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.6 no.2
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    • pp.203-210
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    • 2002
  • In these days, High-strength steel prevails throughout the construction fields for the benefit of structural and economical aspects. But high-strength steel is used by the simple calculation of flexural capacities for the purpose of reducing flexural reinforcement. So, this paper is mainly focused on the shear behavior of high-strength steel reinforced concrete beams without stirrups comparing with normal-strength steel reinforced concrete beams. Specimens were made and tested with the experimental parameters, such as steel yield strength, reinforcement ratios and minimum shear reinforcement. The main result was that not only area but also the yield strength of flexural reinforcement should be considered to predict the shear capacities of concrete beams. In addition, the experimental results were simulated by modified compression field theory analysis program, RESPONSE 2000. A good agreement was achieved between the test results and program analyses.

Effects of Replacement Ratio of Recycled Coarse Aggregate on the Shear Performance of Reinforced Concrete Beams without Shear Reinforcement

  • Yun, Hyun-Do;You, Young-Chan;Lee, Do-Heon
    • Land and Housing Review
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    • v.2 no.4
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    • pp.471-477
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    • 2011
  • This paper will describe the experimental results on the shear behaviors of reinforced concrete (RC) beam with recycled coarse aggregate (RCA). The primary objective of this research is to evaluate the influences of different RCA replacement percentage (i.e, 0%, 30%, 60%, and 100%) on the shear performance of reinforced concrete beams without shear reinforcement. Eight large-scale RC beams without shear reinforcement were manufactured and tested to shear failure. All had a rectangular cross-section with 400mm width ${\times}$ 600mm depth and 6000mm length, and were tested with a shear span-to-depth of 5.1. The results showed that the deflection and shear strength were little affected by the different RCA replacement percentage. Actual shear strength of each RCA beam was compared with the shear strength predicted using the provisions of ACI 318 code and Zsutty'e equation for shear design of RC beams. ACI 318 code predicted the shear strength of RCA reinforced concrete beams well.

Behaviours of steel-fibre-reinforced ULCC slabs subject to concentrated loading

  • Wang, Jun-Yan;Gao, Xiao-Long;Yan, Jia-Bao
    • Structural Engineering and Mechanics
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    • v.71 no.4
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    • pp.407-416
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    • 2019
  • Novel steel fibre reinforced ultra-lightweight cement composite (ULCC) with compressive strength of 87.3MPa and density of $1649kg/m^3$ was developed for the flat slabs in civil buildings. This paper investigated structural behaviours of ULCC flat slabs according to a 4-specimen test program under concentrated loading and some reported test results. The investigated governing parameters on the structural behaviours of the ULCC slabs include volume fraction of the steel fibre and the patch loading area. The test results revealed that ULCC flat slabs with and without flexure reinforcement failed in different failure mode, and an increase in volume fraction of the steel fibre and loading area led to an increase in flexural resistance for the ULCC slabs without flexural reinforcement. Based on the experiment results, the analytical models were developed and also validated. The validations showed that the analytical models developed in this paper could predict the ultimate strength of the ULCC flat slabs with and without flexure reinforcement reasonably well.