• 제목/요약/키워드: high temperature strength

검색결과 3,002건 처리시간 0.043초

Study on bond behavior of steel reinforced high strength concrete after high temperatures

  • Chen, Zongping;Zhou, Ji;Wang, Xinyue
    • Advances in concrete construction
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    • 제10권2호
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    • pp.113-125
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    • 2020
  • This paper presents experimental results on bond-slip behavior of steel reinforced high-strength concrete (SRHC) after exposure to elevated temperatures. Three parameters were considered in this test: (a) high temperatures (i.e., 20℃, 200℃, 400℃, 600℃, 800℃); (b) concrete strength (i.e., C60, C70, C80); (c) anchorage length (i.e., 250 mm, 400 mm). A total of 17 SRHC specimens subjected to high temperatures were designed for push out test. The load-slip curves at the loading end and free end were obtained, the influence of various variation parameters on the ultimate bond strength and residual bond strength was analyzed, in addition, the influence of elevated temperatures on the invalidation mechanism was researched in details. Test results show that the shapes of load-slip curves at loading ends and free ends are similar. The ultimate bond strength and residual bond strength of SRHC decrease first and then recover partly with the temperature increasing. The bond strength is proportional to the concrete strength, and the bond strength is proportional to the anchoring length when the temperature is low, while the opposite situation occurs when the temperature is high. What's more, the bond damage of specimens with lower temperature develops earlier and faster than the specimens with higher temperature. From these experimental findings, the bond-slip constitutive formula of SRHC subjected to elevated temperatures is proposed, which fills well with test data.

고온조건하에서 플라이애시를 사용한 콘크리트의 압축강도증진 해석 (Estimation of Compressive Strength of Fly Ash Concrete subjected to High Temperature)

  • 한민철
    • 한국건축시공학회지
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    • 제6권3호
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    • pp.99-105
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    • 2006
  • In this paper, the estimation of compressive strength of concrete incorporating fly ash subjected to high temperature is discussed. Ordinary Portland cement and fly ash cement(30% of fly ash) were used, respectively. Water to binder ration ranging from 30% to 60% and curing temperature ranging from $20^{\circ}C{\sim}65^{\circ}C$ were also adopted for the experimental parameters. According to results, at the high temperature, FAC had higher strength development at early age than OPC concrete and it kept its high strength development at later age due to accelerated pozzolanic reaction subjected to high temperature. For strength estimation, Logistic model based on maturity equation and Carino model based on equivalent age were applied to verify the availability of estimation model. It shows that fair agreements between calculated values and measured values were obtained evaluating compressive strength with logistic curve. The application of logistic model at high temperature had remarkable deviations in the same maturity. Whereas, the application of Carino model showed good agreements between calculated values and measured ones regardless of type of cement and W/B. However, some correction factors should be considered to enhance the accuracy of strength estimation of concrete.

고온환경 조건하에서 고로슬래그를 사용한 콘크리트의 압축강도 증진 해석 (Estimation of Compressive Strength of Concrete Using Blast Furnace Slag Subjected to High Temperature Environment)

  • 한민철;신병철
    • 한국환경과학회지
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    • 제16권3호
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    • pp.347-355
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    • 2007
  • In this paper, estimation of the compressive strength of the concrete incorporating blast furnace slag subjected to high temperature was discussed. Ordinary Portland cement and blast furnace slag cement (BSC;30% of blast furnace slag) were used, respectively. Water to binder ratio ranging from 30% to 60% and curing temperature ranging from $20^{\circ}C{\sim}65^{\circ}C$ were also chosen for the experimental parameters, respectively. At the high temperature, BSC had higher strength development at early age than OPC concrete and it kept its high strength development at later age due to accelerated latent hydration reaction subjected to high temperature. For the strength estimation, the Logistic model based on maturity equation and the Carino model based on equivalent age were applied to verify the availability of estimation model. It was found that fair agreements between calculated values and measured values were obtained evaluating compressive strength with logistic curve. The application of logistic model at high temperature had remarkable deviations in the same maturity. Whereas, the application of Carino model showed good agreements between calculated values and measured ones regardless of type of cement and W/B. However, some correction factors should be considered to enhance the accuracy of strength estimation of concrete.

자경성 주형의 고온성질에 관한 연구 Calcium-Orthosilicate를 이용한 자경성 주형의 고온성질에 관하여 [I] (A Study on the High Temperature Properties of Self-hardening Sand Mold (High Temperature Properties of Self-Hardening Sand Mold using Calcium-Orthosilicate Powder) [I])

  • 강인찬;한윤희;문인탁
    • 한국세라믹학회지
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    • 제13권1호
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    • pp.20-24
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    • 1976
  • These are many kinds of self-hardening methods for sand mold using sodium silicate. When sodium silicate solution is mixed with calcium-orthosilicate powder hardening reaction occurs, which is based for self-hardening method at high temperature. The high temperature strength and resicual strength of mold are related to the mole ratio of sodium silicate and the contents of calcium-orthosilicate powder. The results obtained in this study were as follows: 1) The high temperature strength of mold was maximum at about $600^{\circ}C$, and at higher temperature showed lower value on the contrary. 2) The high temperature strength of mold was increased by increasing the amount of sodium silicate having lower mole ratio and high concentration. 3) The residual strength of mold was reduced by increasing the mole ratio of sodium silicate and increasing the concentration of calcium-orthosilicate.

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재하와 가열을 받은 초고강도 콘크리트의 크리프 특성 (Creep Properties of Ultra High Strength Concrete at High Temperature under Loading)

  • 이영욱;김규용;최경철;윤민호;김홍섭;이준
    • 한국건축시공학회:학술대회논문집
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    • 한국건축시공학회 2014년도 춘계 학술논문 발표대회
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    • pp.286-287
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    • 2014
  • Performance degradation of Ultra High Strength Concrete occurs more than that of normal strength concrete at high temperature. Thus, strain of concrete subjected to high temperature and loading is one of the core assessment items for evaluating performance of structures. Therefore, in this study, creep of ultra high strength concrete subjected to various temperature conditions and 25%, 40% loading was evaluated. As the results, Creep strain increased with increase of temperature and loading. Creep strain of concrete at high temperature is influenced by loading.

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고온이력이 콘크리트의 강도발현에 미치는 영향에 관한 실험적 연구 (An Experimental Study on the Effects of High temperature Hysteresis on Concrete Strength Development)

  • 김학영;민홍준;장형준;공민호;안무영;정상진
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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    • pp.433-436
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    • 2006
  • This study is basic experiment for estimating influence of strength by curing temperature of concrete's heat of hydration and estimate relationship of compressive strength development by initial curing temperature factor, and then asume temperature factor which influence compressive strength development and for showing basic document of quality control. According to the result of managerial test pieces by the curing temperature factor high-curing temperature shows high strength on 3 day compare with low curing-temperature, shows higher strength than the piece of high curing temperature.

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초기 고온이력을 받은 시멘트 모르타르의 강도 특성에 관한 실험적 연구 (An Experimental Study on the Characteristics of Strength in Mortar under High Temperature conditions in an Early Age)

  • 김영주;김한식;공민호;김제섭;이영도;정상진
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
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    • pp.517-520
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    • 2005
  • This study is basic experiment for estimating influence of strength by curing temperature of concrete's heat of hydration and estimate relationship of compressive strength development by initial curing temperature factor, and then asume temperature factor which influence compressive strength development and for showing basic document of quality control. According to the result of cement mortar by the curing temperature factor high-curing temperature shows high strength on 3 day compare with low curing-temperature, shows higher strength than the piece of high curing temperature.

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모르터 압축강도 특성에 영향을 미치는 고온이력에 관한 실험적 연구 (An Experimental Study on the Characteristics of Strength in Mortar under High Temperature conditions in an Early Age)

  • 김영주;공민호;송인명;양동일;백민수;정상진
    • 한국콘크리트학회:학술대회논문집
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    • 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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    • pp.703-706
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    • 2004
  • This study is basic experiment for estimating influence of strength by curing temperature of concrete's heat of hydration and estimate relationship of compressive strength development by initial curing temperature factor, and then asume temperature factor which influence compressive strength development and for showing basic document of quality control. According to the result of cement mortar by the curing temperature factor high-curing temperature shows high strength on 3 day compare with low curing-temperature, shows higher strength than the piece of high curing temperature.

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적산온도방식에 의한 고유동콘크리트의 강도관리에 관한 실험적 연구 (An experimental Study on the Strength Control of High Fluidity Concrete by Maturity)

  • 김무한;남재현;김규용;길배수;한장현
    • 콘크리트학회논문집
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    • 제12권2호
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    • pp.79-87
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    • 2000
  • The strength development of concrete is influenced by temperature and cement type which greatly affect hydration degree of cement. There is not pertinent concrete strength management methods for estimating the in-place strength of concrete. One such method is the maturity concept. The maturity concept is based on the fact that concrete gains strength with time as a result of the cement hydration and, thus the rate of hydration, as in any chemical reaction, depends primarily on the concrete temperature during hydration. Thus, the strength of concrete is function of its time-temperature history. This goals of the present study are to investigate a relationship between strength of high-fluidity concrete and maturity that is expressed as a function of an integral of the curing period and temperature, predict strength of concrete.

Experimental studies on the material properties of high-strength bolt connection at elevated temperatures

  • Li, Guo-Qiang;Yin, Ying-Zhi;Li, Ming-Fei
    • Steel and Composite Structures
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    • 제2권4호
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    • pp.247-258
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    • 2002
  • The high-temperature material properties of steel are very important to the fire resistance analysis of high-strength bolt connections. This paper reports on the results of the experimental studies on the high-temperature properties of 20 MnTiB steel which is widely used in high-strength bolts, and the friction coefficient of 16Mn steel plates at elevated temperature which is a necessary parameter for bolted frictional connection analysis. The test data includes yield strength, limit strength, modulus of elasticity, elongation and expansion coefficient of 20MnTiB steel at elevated temperature, and the friction coefficients between two 16Mn steel plates under elevated temperatures and after cooling. Based on the data from the tests, the mathematical models for predicting the mechanical properties of 20MnTiB steel and friction coefficients of 16Mn steel plates have been established.