• Title/Summary/Keyword: 정착 거동

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Bond Characteristics of High-Strength Concrete (고장도 콘크리트의 부착특성에 관한 연구)

  • Lee, Joon-Gu;Mun, In;Yum, Hwan-Seok;Kim, Woo
    • Journal of the Korea Concrete Institute
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    • v.13 no.5
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    • pp.499-506
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    • 2001
  • Eight direct tension tests were conducted to study the bond characteristics and crack behavior in high-strength concrete axial members. The main variable was the concrete strength up to 61-63 MPa. The specimens consisted of two different types of the short specimens modeled the part between transverse cracks and the long specimens having numerous transverse cracks. The results obtained show that the bond strength increases in proportion to compressive strength. Thereby, in high-strength concrete the length of stress-disturbed region is shortened and the space of adjacent transverse cracks become smaller. Although the concrete strength varies from 25 MPa to 61 MPa, the split cracking loads remain constant, while transverse cracking loads vary as variation of concrete tensile strength. Accordingly, the current code provisions for development length may need reconsideration in high-strength concrete members, and it is recommended that either thicker cover or transverse reinforcement should be additionally provided for high-strength concrete members.

A Shear Bond Chracteristics of Composite Slab with Closed-Shape Deckplate (폐쇄형 데크플레이트를 사용한 합성슬래브의 전단부착 특성에 관한 연구)

  • Ju, Gi Su;Park, Sung Moo
    • Journal of Korean Society of Steel Construction
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    • v.13 no.5
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    • pp.557-566
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    • 2001
  • Composite slab with deckplate needs sufficient bond strength between deckplate and concrete to conduct composite behavior Composite slab can transfer the shear by either chemical adhesion interface interlock, or active friction. There are several way of mechanical shear connection in composite slab. that is embossments shear connector shape of deckplate etc. Effect of mechanical interaction is deped on shape of deckplate which is to prevent peeling between deckplate and concrete and an amount of shear connector. The behavior and strength of the connection between the decking and the concrete slab due to embossments and end anchorage may be estimated using the push-off tests described in this paper We proposed the equation of shear bond strength in the composite slab It will be use to design by basic data in composite slab.

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Seismic Performance Assessment of Roof-Level Joints with Steel Fiber-Reinforced High-Strength Concrete (강섬유보강 고강도콘크리트를 적용한 최상층 접합부의 내진성능 평가)

  • Kim, Sang-Hee;Kwon, Byung-Un;Kang, Thomas H.-K.
    • Journal of the Korea Concrete Institute
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    • v.28 no.2
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    • pp.235-244
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    • 2016
  • This study was conducted to verify seismic performance of special moment frame's joints at roof-level with high-strength concrete and SD600 bars. K-RC-H was designed according to the seismic code and K-HPFRC-H had 150% of the original hoop spacing and 1.0% steel fiber volume fraction compared with K-RC-H. Both specimens had remarkable seismic performance without noticeable decrease in moment, but with very good energy dissipation before rebar failure. The U-bars in the joint sufficiently constrained rebar's action that pushed the cover upward. SD600 bars with $1.25l_{dt}$ had minimum slip in the joint. It was considered that the steel fiber contributed to improvement of the bending moment and joint shear distortion, and the result showed that it would be possible to increase the hoop spacing to 150% of the regular spacing.

Composition Method and Character for Beam String Structure in Structural Planning (구조계획에 있어 들림형 보구조의 특성과 구성방식)

  • Lee, Ju-Na;Park, Sun-Woo
    • Journal of Korean Association for Spatial Structures
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    • v.6 no.3 s.21
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    • pp.111-121
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    • 2006
  • Beam String Structure is a structure system that is composed with beam, strut and string, and the structural capacity of this structure system is enhanced by introducing prestress force in string and controling the stress and deformation of beam. Researching on the established studies and examples, character and composition methods of Beam String Structure was investigated. At the result, It was examined that the design elements of the system are shape and rise of beam, sag of string, plan arrangement and the composition and number of strut, in addition, detailed composition methods of the design elements were represented. Also, it was showed that the method to form the individual mechanism against additional load can be employed in order to reduce stress of Beam String Structure under the heavy additional load.

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The Behavior of Large Diameter Rock Socketed Piles (암반 정착 대구경 피어기초의 거동특성에 관한 연구)

  • Kim, Tae-Hyun;Kim, Chan-Kook;Hwang, Eui-Seok;Lee, Bong-Real;Kim, Hak-Moon
    • Proceedings of the Korean Geotechical Society Conference
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    • 2006.03a
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    • pp.1245-1250
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    • 2006
  • The rapid growth of the economy recently gas led to increasing social needs for large scaled structures, such as high-rise buildings and long span bridges. In building these large-scaled structures the trend has been to construct foundations beating on or in rock masses in order to ensure stability and serviceability of the structure under several significant loads. However. when designing the drilled shaft foundation socketed in rock masses in Korea, the bearing capacity for the pier used to be determined by using the empirical expression, which depends on the compressive strength of the rock, or presumable bearing capacity recommended on foreign references or manuals. In this study, numerical analyses are used to trace rock-socketed pile behavior and are made alike with pile load test result in field. The result of this numerical analyses study have shown that following factors have a significant influence on the load capacity and settlement of the pier. Significant influence first factor of the geometry of the socket as defined by the length to diameter ratio. Second factor of the modulus of the rock both around the socket and below the base. third factor of the condition of the end of the pier with respect to the removal of drill cuttings and other loose material from the bottom of the socket.

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Evaluating Structural Performance of High-Strength Concrete Corbels Containing Steel and Polypropylene Fibers (강섬유 및 폴리프로필렌 섬유로 보강된 고강도콘크리트 내민받침의 구조 거동 평가)

  • Yang, Jun-Mo;Lee, Joo-Ha;Min, Kyung-Hwan;Yoon, Young-Soo
    • Journal of the Korea Concrete Institute
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    • v.20 no.6
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    • pp.747-754
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    • 2008
  • In this study, high strength concrete corbels reinforced with steel fibers and polypropylene fibers, and subjected to the vertical and horizontal loads were constructed and tested. The results showed that performance in terms of load carrying capacities, stiffness, ductility, crack width, and number of cracks was improved, as the steel fibers and polypropylene fibers were added. The polypropylene fiber reinforced concrete corbels resulted in higher ductility in presence of horizontal loads, but showed larger crack width than the steel fiber reinforced concrete corbels. And, the heads of the headed bars provided excellent end anchorage of the main tension tie reinforcement. Experimental results presented in this paper are also compared with various prediction models proposed by codes and researchers. The refined strut-and-tie model showed more accurate and conservative predictions in presence of horizontal loads, and the truss model proposed by Fattuhi provides fairly good predictions for fiber reinforced concrete corbels.

Seismic Strengthening and Performance Evaluation of Damaged R/C Buildings Strengthened with Glass Fiber Sheet and Carbon Fiber X-Brace System (GFS-CFXB 내진보강법을 이용한 지진피해를 받은 R/C 건물의 내진성능 평가 및 내진보강 효과)

  • Lee, Kang-Seok
    • Journal of the Korea Concrete Institute
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    • v.25 no.6
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    • pp.667-674
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    • 2013
  • Improving the earthquake resistance of buildings through seismic retrofitting using steel braces can result in brittle failure at the connection between the brace and the building, as well as buckling failure of the braces. This paper proposes a new seismic retrofit methodology combined with glass fiber sheet (GFS) and non-compression X-brace system using carbon fiber (CFXB) for reinforced concrete buildings damaged in earthquakes. The GFS is used to improve the ductility of columns damaged in earthquake. The CFXB consists of carbon fiber bracing and anchors, to replace the conventional steel bracing and bolt connection. This paper reports the seismic resistance of a reinforced concrete frame strengthened using the GFS-CFXB system. Cyclic loading tests were carried out, and the hysteresis of the lateral load-drift relations as well as ductility capacities were investigated. Carbon fiber is less rigid than the conventional materials used for seismic retrofitting, resulting in some significant advantages: the strength of the structure increased markedly with the use of CF X-bracing, and no buckling failure of the bracing was observed.

Evaluation of the Load Carrying Capacity of Existing Bridges with Long Span Hollow Web Prestressed Concrete Girder by Static Load Test (정적재하시험을 통한 장경간 중공 웨브 PSC 거더교의 내하력 평가)

  • Kim, Seong-Kyum;Jang, Pan-Ki;Jang, Il-Young
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.22 no.3
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    • pp.97-102
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    • 2018
  • Conventional PSC I type girders were adversely affected by the self - weight of concrete, anchorage, prestressing. In order to overcome this problem, PSC girder was constructed with a hollow in the web and developed a hollow web PSC type I girder which is applicable to 50 - 70m span by multistage stressing and then actually long span hollow web PSC girder bridge was constructed. In this study, the results of Static Load Test and the Finite Element Analysis of the hollow web PSC I girder bridges were compared and analyzed, and the Load Carrying Capacity and safety of PSC girder bridges were evaluated. The Static Load Test and the numerical analysis results of this bridge showed similar tendency and the behavior of the hollow web PSC I girder was well simulated. The entire girders of the bridges had sufficient Load Carrying Capacity under the live load design condition and the bridges satisfied the safety and confirmed the appropriateness of the construction.

Effect of Fiber Volume Fraction on Bond Properties of Structural Synthetic Fiber in Polypropylene Fiber Reinforced Cement Composites (폴리프로필렌섬유보강 시멘트 복합재료에 정착된 구조용 합성섬유의 부착거동에 미치는 섬유 혼입률의 효과)

  • Lee, Jin Hyeong;Park, Chan Gi
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.15 no.4
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    • pp.125-135
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    • 2011
  • The bond properties between polypropylene fiber reinforced cement composites and structural synthetic fiber have been investigated. in this paper. Three levels of polypropylene fibers volume fraction were used, 0.10%, 0.15%, and 0.20% in a series of Dog-bone pull out tests. The bond strength between structural synthetic fiber and polypropylene fiber reinforced cement composites increases with the volume fraction of polypropylene fiber, but the bond strength decreases above the amount of 0.20% by volume of polypropylene fiber reinforced cement composites. Also, the addition of polypropylene fiber a significant improved the interface toughness and the frictional resistance, The microstructure of structural synthetic fiber surface was investigated after the pullout test. The scratched of structural synthetic fiber increased with the polypropylene fiber volume fraction.

Analytical Parametric Study on Pullout Capacity of Embedded Suction Anchors (매입된 석션앵커의 인발력에 대한 분석적 매개변수의 연구)

  • Boonyong, Sorrawas;Park, Ki Chul;Kim, In Chul
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.27 no.3
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    • pp.182-189
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    • 2015
  • The Embedded Suction Anchor (ESA) is a type of permanent offshore foundation that is installed by a suction pile. To increase the loading capacity against pullout, three wings (vertical flanges) are attached along the circumference at 120 degrees apart. Analytical parametric study using the proposed analytical solution method has been conducted to identify the effects of several parameters that are thought to influence the behavior of ESAs. The analysis results show that the pullout capacity increases as the anchor depth and the soil strength increase, and decreases as the load inclination angle increases. The anchor having square projectional area and being pulled horizontally at the middle of its length provides the highest pullout capacity.