• Title, Summary, Keyword: Steel reinforced concrete

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Long-Term Characteristics on Flexural Performance of Steel Fiber Reinforced Concrete Continuous Slab (강섬유보강콘크리트 연속슬래브 휨성능의 장기거동 특성)

  • Hong, Geon-Ho;Jung, Seong-Won
    • Journal of the Architectural Institute of Korea Structure & Construction
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    • v.35 no.10
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    • pp.163-170
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    • 2019
  • In spite of various advantages, steel fiber reinforced concrete is still limited in its use due to the insufficient research results on the structural performance and design criteria. This study evaluated the long-term behavior of the steel fiber reinforced concrete slabs by long-term loading experiments based on the short-term load bearing capacity of steel fiber reinforced concrete slabs obtained from previous studies. In this study, long-term loading experiments were carried out on Total four 2-span continuous slab specimens were tested for examining the long-term behavior of steel fiber reinforced concrete members. Long-term behavior characteristics of members were evaluated by measuring the long-term deflection, drying shrinkage, the number and width of cracks. Experimental results showed that the instant deflection of the steel fiber reinforced concrete slab is about 50% of the normal reinforced concrete slab. And, it was analyzed that the long-term deflection of the specimen using steel fiber reinforced concrete was about 10~20% lower than that of normal concrete by the long-term deflection over 100 days. In addition, the slab specimen using steel fiber reinforced concrete was evaluated to have just 70% of the number and width of cracks compared with normal concrete specimens.

Analysis of steel-GFRP reinforced concrete circular columns

  • Shraideh, M.S.;Aboutaha, R.S.
    • Computers and Concrete
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    • v.11 no.4
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    • pp.351-364
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    • 2013
  • This paper presents results from an analytical investigation of the behavior of steel reinforced concrete circular column sections with additional Glass Fiber Reinforced Polymers (GFRP) bars. The primary application of this composite section is to relocate the plastic hinge region from the column-footing joint where repair is difficult and expensive. Mainly, the study focuses on the development of the full nominal moment-axial load (M-P) interaction diagrams for hybrid concrete sections, reinforced with steel bars as primary reinforcement, and GFRP as auxiliary control bars. A large parametric study of circular steel reinforced concrete members were undertaken using a purpose-built MATLAB(c) code. The parameters considered were amount, location, dimensions and mechanical properties of steel, GFRP and concrete. The results indicate that the plastic hinge was indeed shifted to a less critical and congested region, thus facilitating cost-effective repair. Moreover, the reinforced concrete steel-GFRP section exhibited high strength and good ductility.

Strengthening Efficiency of Ring Type Steel Fibers in Concrete Panels (콘크리트 패널 내 원형 강섬유의 보강 효율성)

  • 조원택;이차돈;최완철
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.327-332
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    • 2001
  • It is generally observed that steel fiber reinforced concrete with traditional straight steel fibers overcomes brittle nature of plain concrete by failure mechanisms by fiber pull-out rather than fiber rupture resulting from fiber yielding or concrete fracture at failured surface. Ring type steel fibers in concrete which is confined in concrete matrix and has better orientation, thus, lead to fiber yielding and concrete fracture as well as increase of flexural behavior of concrete more efficiently, Comparative experimental study is performed in order to measure the relative efficiencies of steel fiber reinforced concrete reinforced with two different fibers. It is found that better toughness is obtained from the ring type steel fiber reinforced concrete than from straight steel fiber reinforced concrete under flexural loading.

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Tests on fiber reinforced concrete filled steel tubular columns

  • Gopal, S. Ramana;Devadas Manoharan, P.
    • Steel and Composite Structures
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    • v.4 no.1
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    • pp.37-48
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    • 2004
  • This paper deals with the strength and deformation of both short and slender concrete filled steel tubular columns under the combined actions of axial compression and bending moment. Sixteen specimens were tested to investigate the effect of fiber reinforced concrete on the ultimate strength and behavior of the composite column. The primary test parameters were load eccentricity and column slenderness. Companion tests were also undertaken on eight numbers of similar empty steel tubes to highlight the synergistic effects of composite column. The test results demonstrate the influence of fiber reinforced concrete on the strength and behavior of concrete filled steel tubular columns.

Prediction of deflection of high strength steel fiber reinforced concrete beams and columns

  • Kara, Ilker Fatih;Dundar, Cengiz
    • Computers and Concrete
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    • v.9 no.2
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    • pp.133-151
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    • 2012
  • This paper presents an analytical procedure for the analysis of high strength steel fiber reinforced concrete members considering the cracking effect in the serviceability loading range. Modifications to a previously proposed formula for the effective moment of inertia are presented. Shear deformation effect is also taken into account in the analysis, and the variation of shear stiffness in the cracked regions of members has been considered by reduced shear stiffness model. The effect of steel fibers on the behavior of reinforced concrete members have been investigated by the developed computer program based on the aforementioned procedure. The inclusion of steel fibers into high strength concrete beams and columns enhances the effective moment of inertia and consequently reduces the deflection reinforced concrete members. The contribution of the shear deformation to the total vertical deflection of the beams is found to be lower for beams with fibers than that of beams with no fibers. Verification of the proposed procedure has been confirmed from series of reinforced concrete beam and column tests available in the literature. The analytical procedure can provide an accurate and efficient prediction of deflections of high strength steel fiber reinforced concrete members due to cracking under service loads. This procedure also forms the basis for the three dimensional analysis of frames with steel fiber reinforced concrete members.

Experimental Evaluation of the Effect of Steel-Seal and Hydro-Seal in Reinforced Concrete Structures (STEEL-SEAL 및 HYDRO-SEAL의 철근콘크리트 구조무에 미치는 영향에 대한 실험적 연구)

  • 전환석;이강균;배수호;정영수
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.287-292
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    • 1997
  • Recent economic growths have accelerating much construction activities of various infrastructures, such as Express railway, Long-span bridges, Multi-story Buildings and etc. Reinforcement steel corrosion to be inevitably caused under the progress of these construction activities have been on and off serious problems in the site, which could incur another tragedic accident to us suffering from safety-ignorance disease. Thus, it is strongly requested to develop probable innovative products which could remove corrosive materials on rebars and also protect steel corrosion of reinforced concrete structures in the construction site. Hydro-Seal and Steel-Seal could solve these problems currently faced with in the construction site. The objective of this research is to experimentally evaluated the effect of Hydro-Seal and Steel-Seal in reinforced concrete structures, of which usage might affect the bond strength between steel and concrete, long-term compressive strength of concrete, corrosion resistance and etc. Related test results show that appropriate dosage of Hydro-Seal and Steel-Seal in reinforced concrete structures didnot affect physical properties of reinforced concrete structures.

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Slip Characteristics of Reinforced Concrete Beams to Corroded Steel State (철근부식상태에 따른 철근콘크리트 보의 슬립특성)

  • 권영웅;최봉섭;정용식
    • Journal of the Korea Concrete Institute
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    • v.11 no.6
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    • pp.129-135
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    • 1999
  • Reinforced concrete structures are constructed under the basic assumption of perfect bonding between steel and concrete. The corrosion of steel in the reinforced concrete beams results in the excessive cracks and gradual deterioration of concrete. This paper are concerned about the slip characteristics of reinforced concrete between steel and concrete. The accelerated test by external power supply was conducted with the three corrosion rates in the laboratory. As a result, it was obtained as follows: (1) the yield strength of steel was reduced according to corrosion states. (2) the equivalent steel area should be considered for detailed analysis. (3) According to the use of corroded steel or not, slip amounts between concrete and steel in test beams increased as the corrosion rate increased. These results can be explained from the bond loss between concrete and steel in test beams.

Mechanical Behavior of Steel Fiber Reinforced Polymer-impregnated Concrete (강섬유보강 폴리머침투콘크리트의 기계적 성질에 관한 연구)

  • 변근주;송영철;정해성;정기영
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.156-161
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    • 1993
  • This paper is to develop steel fiber reinforced polymer-impregnated concrete(SFPIC) by impregnation polymer impregnate into hardened steel fiber reinforced concrete(SFRC). Steel fiber induces ductile behavior and polymer impregnant increase compressive strength. Steel fiber reinforced polymer-impregnated concrete specimens are prepared with fiber contents of 0.0, 1.5, 2.0, 2.5% and tested to obtain uni-axial and bi-axial compression strengths, tensile strength and flexural strength. The strength and mechanical properties of normal concrete, SFRC, SFPIC are compared.

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Effect of Mixer on the Performance of Ultra-High Strength Steel Reinforced Concrete (초고강도 강섬유 보강 콘크리트의 성능에 미치는 믹서의 영향)

  • Park, Jung-Jun;Koh, Kyung-Taek;Ryu, Gum-Sung;Kang, Su-Tae;Kim, Sung-Wook;Han, Sang-Mook
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.549-552
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    • 2006
  • Generally the ultra-high strength steel reinforced concrete has rich mix composition composed of high-strength type mineral admixtures and as a result of very low water-binder ratio(about under w/b=25%), it reveals ultra-high compressive strength(about over 100Mpa). Also, in order to obtain sufficient toughness after construction, we usually mix a large quantity steel fiber with ultra-high strength steel reinforced concrete therefore we must use proper mixer for workability. When we make the ultra-high strength steel reinforced concrete we need more long mixing time or much super-plasticizer than when we manufacture normal concrete. These bring about economical problems and performance deterioration. Therefore, in this study, in order to manufacture easily ultra-high strength steel reinforced concrete we develope a dedicated mixer for ultra-high strength steel reinforced concrete with high speed type. It carried out the examination for comparison between the dedicated and general type mixer, the analysis and counterplan of the point at issue when we manufacture ultra-high strength steel reinforced concrete by the dedicated mixer.

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Compressive strength and failure behaviour of fibre reinforced concrete at elevated temperatures

  • Shaikh, F.U.A.;Taweel, M.
    • Advances in concrete construction
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    • v.3 no.4
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    • pp.283-293
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    • 2015
  • This paper presents the effects of elevated temperatures of $400^{\circ}C$ and $800^{\circ}C$ on the residual compressive strength and failure behaviour of fibre reinforced concretes and comparison is made with that of unreinforced control concrete. Two types of short fibres are used in this study e.g., steel and basalt fibres. The results show that the residual compressive strength capacity of steel fibre reinforced concrete is higher than unreinforced concrete at both elevated temperatures. The basalt fibre reinforced concrete, on the other hand, showed lower strength retention capacity than the control unreinforced concrete. However, the use of hybrid steel-basalt fibre reinforcement recovered the deficiency of basalt fibre reinforced concrete, but still slightly lower than the control and steel fibres reinforced concretes. The use of fibres reduces the spalling and explosive failure of steel, basalt and hybrid steel-basalt fibres reinforced concretes oppose to spalling in deeper regions of ordinary control concrete after exposure to above elevated temperatures. Microscopic observation of steel and basalt fibres surfaces after exposure to above elevated temperatures shows peeling of thin layer from steel surface at $800^{\circ}C$, whereas in the case of basalt fibre formation of Plagioclase mineral crystals on the surface are observed at elevated temperatures.