• 제목/요약/키워드: Concrete structures

검색결과 6,724건 처리시간 0.039초

외부 프리스트레싱과 탄소섬유판을 결합한 콘크리트 구조물 보강 (Strengthening of Concrete Structures with External Post-Tensioning and CFRP Strips)

  • 임동환;박성환;김용일
    • 한국콘크리트학회:학술대회논문집
    • /
    • 한국콘크리트학회 2006년도 추계 학술발표회 논문집
    • /
    • pp.165-168
    • /
    • 2006
  • Carbon fiber reinforced polymer(CFRP) have superior mechanical and chemical properties in comparison with conventional materials. And post-tensioning method has been used for structural reinforcement of RC structures due to easy installation and good effect of resisting capacity of structures. But the higher cost of CFRP and the loss of prestressing force with time are considered the major problems to use it. In this study, CFRP Strips and external post tensioning for rehabilitation of old concrete structures were adapted and optimal combination of these methods is considered. A total of 17 concrete members were made and tested. The types and numbers of CFRP strips and post-tensioning types were selected as major test variables. From test results, it is shown that the concrete members that post tensioned and bonded CFRP strips has a pronounced effect on the strength and deformational behavior. This present study indicates that external temporally post tensioning can reduce the amount of CFRP strips required and the combination of temporally post tensioning and CFRP strips may meet the strength and ductility requirements of old structures.

  • PDF

지하구조물을 위한 수밀콘크리트의 개발 및 실용화 (Development and Application of Low Permeable Concrete for Underground Structures)

  • 백상현;박성수;박종유;백원준;엄태선;최롱
    • 한국콘크리트학회:학술대회논문집
    • /
    • 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
    • /
    • pp.259-262
    • /
    • 1999
  • In underground reinforced concrete structures, such as drainage structure, water and chloride ion penetrated into concrete through the cracks of concrete and its permeable property, cause the corrosion of reinforcing steel bar, which accelerates the expansive cracks and deterioration of concrete. It is necessary to control those deterioration of underground structure by improving its permeability and durability through the reasonable solutions in design, construction and materials. In the present study, fly ash concrete, which has good material properties in long-term period, was compared and studied with plain concrete using ordinary portland cement in terms of fundamental mechanical properties, permeability, drying shrinkage and durability. Also, the mix design and field test of low permeable concrete using fly ash were performed. From this study, fly ash concrete can control the penetration of water and chloride ion effectively by forming dense micro-structure of concrete. Therefore, fly ash concrete may increase the long-term function, performance and serviceability of underground structures.

  • PDF

동해안 39개 철도구조물의 염화물 함유량과 중성화에 대한 현황분석 (Current Status on the Chloride Content and Carbonation of Train Structures in the East)

  • 이영재;김용희;이윤영
    • 한국구조물진단유지관리공학회 논문집
    • /
    • 제7권1호
    • /
    • pp.259-266
    • /
    • 2003
  • Recently, the premature corrosion for reinforced concrete structure exposed to chloride bring about a serious problem in concrete structures. Specially, the concrete structures of sea coast are exposed much to chloride which make rapid corrosion. Thus, construction activities and maintenances for marine facilities are more demanded than those for land structures. The results of this study have been analysed to identify the extent of chloride content and incidence of carbonation for construction age. After measuring chloride content in concrete, it was conclued that about 90% of all tests on concrete samples exceed the acceptable maximum limit to risk of chloride-induced carbonation. The carbonation rate coffnient by age of train structures in the east eatimated 6. 55, 4.76 grater than 3. 727. In the basis of this result, it is necessary to maintenance for the important train facilities with the regular tests of chloride and carbonation.

염해를 받는 콘크리트 구조물의 내구수명 평가에 관한 연구 (A Study on Service Life Evaluation for Concrete Structures Subjected to Chloride Attack)

  • 송하원;백승우;변근주;성낙일
    • 한국콘크리트학회:학술대회논문집
    • /
    • 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
    • /
    • pp.229-232
    • /
    • 2004
  • In order to ensure the construction of sustainable reinforced concrete structures, durability evaluation of RC structures before construction should be carried out. In this paper, a service life evaluation technique using a safety factor determined by a reliability theory for RC structures subjected to chloride attack is proposed. The life safety factor and the service life evaluation .proposed in this paper can be applied consistently for the durability evaluation of recently developed Korean standard specification for durability of concrete structures which be used effectively for the evaluation before construction and maintenance for RC structures under chloride attack.

  • PDF

콘크리트 표면밀도 증가에 의한 원전구조 성능개선 연구 (The research for the durable-performance improvement of nuclear concrete structures by increasing the density of concrete surface layer)

  • 최홍식;이시우;허권;이상민
    • 한국콘크리트학회:학술대회논문집
    • /
    • 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
    • /
    • pp.253-256
    • /
    • 2006
  • For nuclear concrete structures on the coast, the prevention and management against salt damage is needed because they are being under the influence of the sea water at all times. In general, the deterioration of the concrete is generated in concrete surface firstly and then extended into concrete gradually as its service life increases. Therefore, the protective layer on the concrete surface is needed to establish and manage the durability of concrete. To enhance the durability performance of the existing and new concrete, the development and application of a high-performance penetration sealer is needed. The sealer has to have the functions that are able to prevent the attack of the moisture, carbon dioxide, and harmful substance from the outside. Therefore, the aim of this project is to guarantee the long service-life and waterproof performance of a nuclear concrete structures by increasing the density of the existing and new concrete surface layer, and to enhance the dust-proof performance of the uncoating part of the nuclear safety-relative structures.

  • PDF

섬유보강 철근콘크리트 보의 전단강도 평가 (Shear Strength of Reinforced Concrete Beams Strengthened by Fiber Reinforced Polymer)

  • 황현복;이정윤
    • 한국콘크리트학회:학술대회논문집
    • /
    • 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
    • /
    • pp.401-404
    • /
    • 2004
  • In recent years, the use of fiber reinforced polymer (FRP) composites to repair or strengthen existing reinforced concrete (RC) structures is increasing In order to evaluate the shear strengths of RC structures strengthened by FRP composites, it is needed to understand the shear failure modes of these structures. This paper presents a rational equation to distinguish the shear fail modes of RC structures strengthened by FRP composites using the compatibility aided truss models.

  • PDF

Two-dimensional water seepage monitoring in concrete structures using smart aggregates

  • Zou, Dujian;Li, Weijie;Liu, Tiejun;Teng, Jun
    • Structural Monitoring and Maintenance
    • /
    • 제5권2호
    • /
    • pp.313-323
    • /
    • 2018
  • The presence of water inside concrete structures is an essential condition for the deterioration of the structures. The free water in the concrete pores and micro-cracks is the culprit for the durability related problems, such as alkali-aggregate reaction, carbonation, freeze-thaw damage, and corrosion of steel reinforcement. To ensure the integrity and safe operation of the concrete structures, it is very important to monitor water seepage inside the concrete. This paper presents the experimental investigation of water seepage monitoring in a concrete slab using piezoelectric-based smart aggregates. In the experimental setup, an $800mm{\times}800mm{\times}100mm$ concrete slab was fabricated with 15 SAs distributed inside the slab. The water seepage process was monitored through interrogating the SA pairs. In each SA pair, one SA was used as actuator to emit harmonic sine wave, and the other was used as sensor to receive the transmitted stress wave. The amplitudes of the received signals were able to indicate the water seepage process inside the concrete slab.

Size Estimation of Concrete Structures Using the Impact Echo Method

  • Hong, Seong-Uk;Yoon, Sang-Ki;Lee, Yong-Taeg;Kim, Seung-Hun
    • Architectural research
    • /
    • 제22권1호
    • /
    • pp.23-31
    • /
    • 2020
  • This study aims to verify a method for accurately estimating the sizes of the column, slab, and beam members of concrete structures using the impact echo method, which is a nondestructive testing method. The concrete specimens are designed and fabricated with six single-layer frame specimens composed of columns, slabs, and beam members based on three strengths of 24, 30, and 40 MPa. To estimate the sizes of the members according to the member types of concrete structures, the experiment was performed using the impact echo method. As a result of estimating the sizes of the concrete column members using the impact echo method, the error rate is 2.9%. As a result of estimating the depth of the concrete beam members, the error rate is 9.7%. And, as a result of estimating the thickness of the concrete slab members, the error rate is 2.4%. These results confirmed that quality control of the members of concrete structures is possible by estimating their sizes using a non-destructive testing method.