• Title/Summary/Keyword: Bending reinforcement

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Experimental Study for the Bending Behavior of Precast Concrete Panel and Composite Deck for Railway Bridge (철도교 바닥판용 프리캐스트 패널과 합성 바닥판의 휨거동에 대한 실험적 연구)

  • Seol, Dae-Ho;Lee, Kyoung-Chan;Youn, Seok-Goo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.3
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    • pp.21-31
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    • 2018
  • This paper presents an experimental investigation on the structural performance of precast ribbed panel specimens and bridge deck specimens fabricated from the panels. The panel specimens are developed for permanent deck forms of railway bridges (PSC girder). The decks of railway bridges have short lengths compared with highway bridges. Therefore, precast panels for railway bridges are different from those of highway bridges. The precast panels have ribs designed for crack control at the bottom of the sections. Two kinds of specimens were examined: one with 400-mm width and one with 1200-mm width. Three specimens of each type were fabricated, and a total of 12 specimens were tested. In this test, the ultimate load, strain of the reinforcement and concrete, crack width, deformation, and slip were measured. The structural performance of the specimens was assessed using the Korea railway bridge design code and Eurocode. All specimens met the current design criteria for structural strength and serviceability.

Numerical study on structural reinforced effects of concrete lining by spray-applied waterproofing membrane (차수용 박층 멤브레인 설치에 따른 콘크리트 라이닝의 구조적 보강효과에 관한 수치해석 연구)

  • Lee, Chulho;Lee, Kicheol;Kim, Dongwook;Choi, Soon-Wook;Kang, Tae-Ho;Chang, Soo-Ho
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.19 no.3
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    • pp.551-565
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    • 2017
  • A spray-applied waterproofing membrane which consists of polymers has a relatively higher constructability and adhesion than the conventional sheet-type waterproofing materials. Additionally, the spray-applied waterproofing membrane generally shows a waterproofing ability as a composite structure with shotcrete or concrete lining. Because its purpose is waterproofing at the structure, structural effects were not well reported than waterproofing abilities. In this study, structural effects of the membrane-attached concrete lining were evaluated using 3-point bending test by the numerical method. From the analysis, a load-displacement behavior of the concrete lining and fracturing energy after yielding were compared with various conditions. Consequently, concrete lining with spray-applied waterproofing membrane shows higher flexural strength and fracturing energy than the single-layer concrete lining.

FE Analysis of the Composite Action in the Composite Beam subjected to the Hogging Moment (부모멘트를 받는 합성보의 전단합성 거동에 대한 유한요소해석)

  • Shin, Hyun-Seop
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.8
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    • pp.4048-4057
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    • 2013
  • In the composite beam subjected to the hogging moment it is very difficult to evaluate the influence of the reduction of slab stiffness due to cracks and their development on the horizontal shear behavior of shear connection. In this study, a 3D FE model is developed by which one can analyze the composite action in the composite beam subjected to the hogging moment. In this FE model, each structural member and shear connection are modeled as similar as possible to details of the composite beam. Bending behaviour, and composite action which could not be analyzed using the existing 1D or 2D FE model are investigated by the 3D model. Analysis results show that the reinforcement ratio and crack behaviour of the slab are main factors which exert a strong influence on the composite action. According to the analysis results about load-slip behavior, initial crack of slab and yielding of rebars have a influence on the slip stiffness of shear connection. The existing experimental results, that the design of partial interaction can be more efficient in designing of shear connection of the composite beams, are indirectly verified by the FE analysis.

Characteristic of Buckling and Ultimate Strength of the Perforated Stiffened Plate (유공보강판의 좌굴 및 극한강도 특성에 관한 연구)

  • Park Joo-Shin;Ko Jae-Yong;Oh Kyoung-Gun
    • Journal of Navigation and Port Research
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    • v.30 no.6 s.112
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    • pp.439-446
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    • 2006
  • In ship structures many of the structural plates have cutouts, for example, at inner bottom structure, girder, upper deck hatch, floor and dia-frame etc. In the case where a plate has a cutout it experiences reduced buckling and ultimate strength and at the same time the in-plane stress under compressive load produced by hull girder bending will be redistributed In general, actual ship structure adopted reinforcement of stiffener around the cutout in order to preventing from buckling so it need to examine a buckling and ultimate strength behaviour considering a cutout because In many ship yards used class rule for calculating buckling strength but it is difficult to evaluate perforate stiffened plate with random size. In the present paper, we investigated several kinds of perforated stiffened model from actual ship and then was performed finite element series analysis varying the cutout ratio, web height, thickness and type of cross-section using commercial FEA program(ANSYS) under compressive load.

A Study on the Simple Design Method of Semi-Rigid Connection with Angle in Steel Structure (강구조에서 ㄱ형강을 이용한 반강접 접합의 간편 설계)

  • Heo, Myong-Jae;Kim, Hong-Geun;Choi, Won-Gu
    • Journal of Korean Society of Steel Construction
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    • v.23 no.3
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    • pp.261-273
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    • 2011
  • Recently, the demands for steel frame are increasing because of the trend and due to the demand for bigger and higher buildings. In the analysis of typical steel frame, connections are based on the idealized fixed or pinned connection. A fixed connection assumes that the relative angle of each member before deformation is the same after the transformation. Therefore, the stiffener reinforces the connection to sufficient rigidity and stability of the panel zone. In the economical aspect, however, the necessity of connection that the stiffener reinforcement has omitted is increasing due to the excessive production as well as labor costs of connection. In contrast, pinned connection is assumed that bending moments between the beams and columns do not transfer to each member. This is easy to make in the plant and the construction is simple. However, the structural efficiency is reduced in pinned connection because connection cannot transfer moments. The introduction of this semirigid process can decide efficient cross-sectional dimensions that promote ease in the course of structural erection, as performed by members in the field-a call for safety in the entire frame. Therefore, foreign countries exert efforts to study the practical behavior and the results are applied to criterion. This paper analyzes the semirigid connection of domestic steel by design specifications of AISC/LRFD and make data bank that pertain to each steel. After wards, the results are compared to those of idealized connection; at the same time, this paper presents a design method that matches economic efficiency, end-fixity, and rotational stiffness.

A Study on the Change of Tensile Force of Friction Type Anchor under Shear Deformation of Ground (지반의 전단변형에 따른 마찰형 앵커의 긴장력 변화에 대한 연구)

  • You, Min-Ku;Kwon, O-Il;Lee, Sang-Duk
    • Journal of the Korean Geotechnical Society
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    • v.34 no.4
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    • pp.13-25
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    • 2018
  • When deformation occurs on slope reinforced with anchor, shear stress and bending stress are applied on the shear surface along the slip surface and increase of the shear deformation causes the tension force variation of the anchor. In this study, shear test was performed by measuring the tension force of the anchor by inducing shear deformation in vertical direction of the anchor using a large-scale direct shear test equipment in order to confirm the tension force variation of the anchor induced by shear deformation. The shear test was performed for 8 conditions which were classified according to the anchor reinforcement, separation distance (1D, 2D, 4D) from the shear surface to bonded part and the lateral-pressure condition (0.1 MPa, 0.2 MPa) of adjacent ground. As a result of the shear test, it was found that the separation distance and the lateral-pressure condition affect the shear force of the ground reinforced by anchor and the tension force of the anchor, and experimentally verified that the shear force variation is related to axial force variation of the anchor head and tip. Therefore, it was confirmed that the behavior of the bonded part induced by the shear deformation can be indirectly predicted by analyzing the tendency of the tension force variation of the anchor head.

Flexural Behavior of RC Beams Strengthened with Steel Strand and Carbon Fiber Sheet (강연선 및 탄소섬유쉬트로 보강된 철근 콘크리트 보의 휨거동 특성)

  • 양동석;박선규;이용학
    • Journal of the Korea Concrete Institute
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    • v.14 no.2
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    • pp.216-222
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    • 2002
  • With deterioration of the nation's infrastructure comes the growing, need for effective means of rehabilitating structures. Possibly one for the most challenging tasks is to upgrade the overall capacity of concrete structure. Therefore, considerable efforts are still being made to develop new construction materials. Rehabilitation of damaged RC structures occasionally requires the removal and replacement of concrete in the tension zone of the structural members. Typical situation where the tension zone repair is necessary is when the concrete in the tension zone in beams or slabs has spalled off as a result of corrosion in the bottom reinforcing bars or due to extensive fire. The rehabilitation of such conditions normally involves the removal of the concrete beyond the reinforcement bars, cleaning or replacing the tensile bars and reinstatement of concrete to cover the steel bars the original shape and size. This study focused on the flexural behavior of reinforced concrete beams strengthened by steel strand and carbon fiber sheet in the tension zone. The properties of beams are 15$\times$25 cm rectangular and over a 200cm span. Test parameters in this experimental study were strengthening methods, jacking volume, the number of sheet. We investigated the flexural behavior of simply supported RC beams which are strengthened with the carbon fiber sheet, monotonic loads. Attention is concentrated upon overall bending capacity, deflection, ductility index, failure mode and crack development of repaired and rehabilitated beams.

Characteristics of Shear Behavior of Reinforced Concrete Beams Strengthened with Near Surface Mounted CFRP Strips (CFRP 스트립 표면매립공법으로 보강된 철근콘크리트 보의 전단거동 특성)

  • Han, Sang Hoon;Hong, Ki Nam;Shin, Byoung Gil;Lim, Jin Mook;Kwak, So Shin
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.15 no.5
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    • pp.178-189
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    • 2011
  • Tests and analyses were performed in this study to assess the shear strength of Reinforced Concrete(RC) members strengthened by the Near Surface Mounted(NSM) technique in shear, which is drawing attention as an alternative to the Carbon Fiber Reinforced Polymer(CFRP) bonding strengthening technique. Four-point bending tests were performed on 7 RC specimens without any shear reinforcement. The test variables such as the inclination of CFRP strip (45 degrees and 90 degrees), and the spacing of CFRP strip (250mm, 200mm, 150mm, 100mm) were considered. Through the testing scenarios, the effect of each test variable on the failure mode and the shear strength of the RC members strengthened by the NSM technique in shear were assessed. The test results show that the specimens with CFRP strips at 45 degrees go to failure as a result of the strip fracture, but the specimens with CFRP strips at 90 degrees go to failure as a result of the slip of strips. Strips at 45 degrees was the more effective than strips at 90 degrees, not only in terms of increasing beam shear resistance but also in assuring larger deformation capacity at beam failure. In addition, the RBSN analysis appropriately predicted the crack formation and the load-displacement response of the RC members strengthened by the NSM technique in shear.

Performance Test of Wall to Wall Modular Structure Joint for Near-surface Transit (저심도 모듈식 구조체의 벽체간 연결 조인트 성능검증 실험)

  • Lee, Jong Soon;Kim, Hee Sung;Lee, Sung Hyung;Lee, Jun Kyoung
    • Journal of the Korean Society for Railway
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    • v.18 no.3
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    • pp.261-269
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    • 2015
  • To overcome the weaknesses of viaduct bridges and the non-economic efficiency of underground LRT, the study of near-surface railway systems is in progress. To apply a box structure to the low depth transit, a connection joint to precast modules are very important when applying precast modular structures to replace temporary structures. In this study, wall to wall connections were applied in diverse cases such as rebar connections, guiding structures that were used to fit the verticality of precast walls during construction, and non-reinforcement structures used only for waterstop. Experimental performance verification was carried out for the bending, shear and splitting of the wall to wall connection. Precision of construction joints between wall to wall was identified as a factor that influenced the structural performance of the precast wall. A structure that can serve as a guide during the vertical insertion of a wall is confirmed for the most suitable case, but it will be necessary to modify this structure for detailed cases.

Experimental Study on Engineering Performance Evaluation and Field Performance of Environmentally Friendly Functional Concrete (친환경 기능성 콘크리트의 공학적 성능평가 및 현장적용성능에 관한 실험적 연구)

  • Lee, Byung-Jae;Park, Seong-Bum;Kim, Yun-Yong;Jang, Young-Il
    • Journal of the Korea Concrete Institute
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    • v.24 no.2
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    • pp.165-172
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    • 2012
  • In this study, the physical, mechanical, structural, and environmental performances based on field measured data were evaluated to check the suitability of concrete for ecological preservation and cultivation of a hydrophilic environment. More specifically, the study is focused on developing an environmentally friendly functional concrete with river ecology restoration and natural river early formation capabilities. The mechanical performance evaluation results showed that the increase in mix rate of the PVA (Poly Vinyl Alcohol) reinforcement fibers and silica fume caused an increase in the strength. The optimal mix rate was found to be 0.05 volume % PVA fiber and approximately 10% silica fume. The frost resistance evaluation showed that superior performance was gained when 0.05 volume % PVA fiber and 15% silica fume was mixed simultaneously. In the structural performance evaluation, the bending strength was improved by 47.7% compared to plain concrete when mixed with 0.05 volume % PVA fiber. The flexural toughness also saw significant improvement. The environmental monitoring of field performance showed that grasses germinated most rapidly, but the growth of red poppies, a plant that germinates in the spring, was most active with passing of time. Coverage measurements in all of the monitoring locations found favorable coverage of over 95% after 12 weeks. The study results showed that the environmentally friendly functional concrete had outstanding environmental performance.