이형철근과 FRP 보강근의 복합 이중근을 갖는 FRC 보의 휨성능을 평가하기 위하여 실험이 수행되었다. 인장근의 종류(CFRP 보강근, GFRP 보강근, 철근)과 PVA 섬유 혼입률(0.5%, 0%)을 주요변수로 한 7개의 실험체를 제작하였다. 유한요소해석을 통하여 FRC 보의 균열 및 휨거동을 예측하기 위한 해석적 방법이 제안되고 분석되었다. 복합 이중근을 가지는 실험체들에서 철근으로 이중근을 가지는 실험체가 철근과 FRP 보강근을 이단으로 배치한 실험체들에 비하여 26~34% 균열하중이 큰 것으로 나타났다. 최대 휨강도에서는 복합 이중근을 가지는 실험체들 중 CFRP 보강근을 최외측으로 한 실험체가 가장 큰 내력을 나타내었다. 해석과 실험을 통한 휨강도를 비교한 결과, 강도비는 평균 1.2, 표준편차 0.085, 최대 오차율은 22% 등으로 나타났다. 이러한 결과에서 본 연구의 유한요소해석방법이 복합 이중근을 가지는 보의 실제 거동을 효과적으로 표현할 수 있음을 알 수 있다.
이형철근과 FRP 보강근의 복합 이중근을 갖는 FRC 보의 휨성능을 평가하기 위하여 실험이 수행되었다. 인장근의 종류(CFRP 보강근, GFRP 보강근, 철근)과 PVA 섬유 혼입률(0.5%, 0%)을 주요변수로 한 7개의 실험체를 제작하였다. 유한요소해석을 통하여 FRC 보의 균열 및 휨거동을 예측하기 위한 해석적 방법이 제안되고 분석되었다. 복합 이중근을 가지는 실험체들에서 철근으로 이중근을 가지는 실험체가 철근과 FRP 보강근을 이단으로 배치한 실험체들에 비하여 26~34% 균열하중이 큰 것으로 나타났다. 최대 휨강도에서는 복합 이중근을 가지는 실험체들 중 CFRP 보강근을 최외측으로 한 실험체가 가장 큰 내력을 나타내었다. 해석과 실험을 통한 휨강도를 비교한 결과, 강도비는 평균 1.2, 표준편차 0.085, 최대 오차율은 22% 등으로 나타났다. 이러한 결과에서 본 연구의 유한요소해석방법이 복합 이중근을 가지는 보의 실제 거동을 효과적으로 표현할 수 있음을 알 수 있다.
Experimental programs were performed to evaluate the flexural performance of fiber reinforced concrete(FRC) beams using a hybrid double-layer arrangement of steel bars and fiber reinforced polymer(FRP) bars or using FRP bars only. A total of seven beam specimens were produced with type of tensile re...
Experimental programs were performed to evaluate the flexural performance of fiber reinforced concrete(FRC) beams using a hybrid double-layer arrangement of steel bars and fiber reinforced polymer(FRP) bars or using FRP bars only. A total of seven beam specimens were produced with type of tensile reinforcing bar(CFRP bar, GFRP bar, steel bar) and the poly vinyl alcohol(PVA) fiber mixing ratio(0.5%, 0%) as variable. An analysis method for predicting the flexural behaviors of FRC beams with hybrid arrangement of heterogeneous reinforcing bars through finite element analysis was proposed and verified. In case of the specimens with the double-layer reinforcing bars, the test results showed that the first cracking load of specimen with a double-layer arrangement of steel bars was greater by 26-34% than specimens with a hybrid double-layer arrangement of steel and FRP bars. In maximum flexural strengths, the specimen that used CFRP bars as bottom tensile reinforcing bar showed the greatest strength among the specimens with the double-layer reinforcing bars. When the maximum moment value obtained through experiments was compared with that obtained through analysis, the ratio was 1.2 on average, the standard deviation was 0.085, and the maximum error rate was 22% or less. Based on these results, the finite element analysis model proposed in this study can effectively simulate the actual behavior of the beams with hybrid double-layer reinforcing bars.
Experimental programs were performed to evaluate the flexural performance of fiber reinforced concrete(FRC) beams using a hybrid double-layer arrangement of steel bars and fiber reinforced polymer(FRP) bars or using FRP bars only. A total of seven beam specimens were produced with type of tensile reinforcing bar(CFRP bar, GFRP bar, steel bar) and the poly vinyl alcohol(PVA) fiber mixing ratio(0.5%, 0%) as variable. An analysis method for predicting the flexural behaviors of FRC beams with hybrid arrangement of heterogeneous reinforcing bars through finite element analysis was proposed and verified. In case of the specimens with the double-layer reinforcing bars, the test results showed that the first cracking load of specimen with a double-layer arrangement of steel bars was greater by 26-34% than specimens with a hybrid double-layer arrangement of steel and FRP bars. In maximum flexural strengths, the specimen that used CFRP bars as bottom tensile reinforcing bar showed the greatest strength among the specimens with the double-layer reinforcing bars. When the maximum moment value obtained through experiments was compared with that obtained through analysis, the ratio was 1.2 on average, the standard deviation was 0.085, and the maximum error rate was 22% or less. Based on these results, the finite element analysis model proposed in this study can effectively simulate the actual behavior of the beams with hybrid double-layer reinforcing bars.
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제안 방법
5% and placed steel bars on top and CFRP, GFRP, and steel bar at the bottom as flexural tension members. The singlelayer specimens mixed PVA fibers in two ratios, 0.5% and 0%, to examine the effect of PVA fiber reinforcement, and placed CFRP and GFRP bars as flexural tension members. The specimens were designed with cross section of 200 mm×300 mm, length of 3000 mm, clear span of 2600 mm, depth of inner reinforcing bar as 200 mm, and the depth of outer reinforcing bar as 260 mm.
The specimens were planned in two types: single-layer and double-layer arrangements depending on the placement of tensile reinforcing bars. The double-layer specimens mixed PVA fibers at 0.
Especially the research on the flexural performance of FRC members with hybrid arrangement of steel and FRP bars is insufficient. Therefore, in this study, flexural tests were conducted to evaluate the flexural performance of FRC beams with a hybrid arrangement of steel and FRP bars and FRC beams using FRP bars only. In addition, an analysis method for predicting the flexural behavior and cracks of FRC beams with hybrid arrangement of heterogeneous reinforcing bars through finite element analysis was proposed and verified.
(2011) fabricated 10 specimens and conducted experiments with them to examine the behaviors of beams with a hybrid arrangement of FRP and steel bars. They analyzed such behaviors as crack patterns, rigidity after cracking, deflection, and ductility. Their experimental results showed that the hybrid arrangement of heterogeneous reinforcing bars could control large deflection, crack depth and width.
대상 데이터
The experiment was carried out using the universal testing machine (UTM) until every specimen was fractured by the compressive failure of concrete. Fig.
The specimens were designed with cross section of 200 mm×300 mm, length of 3000 mm, clear span of 2600 mm, depth of inner reinforcing bar as 200 mm, and the depth of outer reinforcing bar as 260 mm.
이론/모형
To examine the material properties of steel and FRP bars used in this experiment, the material experiment was conducted in accordance with KS B 0801. Three experiments were performed for each material, and their average values were calculated to derive the resultant value.
성능/효과
2) For rigidity after cracking, the specimens with a hybrid arrangement of FRP and steel bars showed a lower rigidity than that of the specimens with steel bars only. Furthermore, when the maximum strengths of the specimens were compared, the specimen that arranged the CFRP bar as bottom tensile reinforcing bar (P1-SC) showed the greatest maximum strength among the specimens with a double-layer arrangement of steel and FRP bars.
3) The differences in rigidity and flexural strength depending on the mixing of fibers were not significant. However, the specimens mixed with fibers (P0-C, P0-G) showed greater deflections than the specimens with no fibers (P0-C, P0-G) under the maximum load, suggesting excellent strain performance.
4) The P1-C specimen was designed to fail by the concrete crushing fracture, but it failed by the fracture of the CFRP bar in the end. The reason for this seems to be the fact that the extreme compressive strain of the fiber-reinforced concrete increased.
Based on this, it was concluded that the finite element analysis model proposed in this study simulates the actual behavior of the beams reinforced with FRP bars and PVA fibers relatively accurately.
The design criterion strength is 35 MPa and 100 mm×200 mm concrete specimens were fabricated to perform standard compressive strength test according to the existence or absence of fiber reinforcement. The experiment results showed that the compressive strength of specimen was 20.5 MPa for fiber-reinforced specimens and 21.4 MPa for other specimens. The concrete mixing ratio is shown in Table 3.
The steel and AFRP bars were arranged in a single layer on the same line in the tensile section of the beam or in double layers by placing the steel bar on top of AFRP bar. The experimental results showed that the additional arrangement of steel bar on the concrete section reinforced with AFRP bar significantly increased the ductility of structure and reduced the width and gaps of cracks. However, the contribution of the additionally arranged steel bar to the flexural performance did not exceed 15%.
They analyzed such behaviors as crack patterns, rigidity after cracking, deflection, and ductility. Their experimental results showed that the hybrid arrangement of heterogeneous reinforcing bars could control large deflection, crack depth and width.
후속연구
Based on this, it was concluded that the finite element analysis model proposed in this study simulates the actual behavior of the beams reinforced with FRP bars and PVA fibers relatively accurately. However, further research is necessary to attain the reliability of the analysis model results in the case of various parameter analyses in future.
참고문헌 (14)
ACI 440.1R-15. (2015), Guide for the Design and Construction of Structural Concrete Reinforced with Fiber-Reinforced Polymer (FRP) Bars, American Concrete Institute.
Aiello, M. A., and Ombres, L. (2002), Structural performances of concrete beams with hybrid (fiber-reinforced polymer-steel) reinforcements, Journal of Composites for Construction, 6(2), 133-140.
Barris, C., Torres, L. I., Turon, A., Baena, M., and Catalan, A. (2009), An experimental study of the flexural behaviour of GFRP RC beams and comparison with prediction models. Compos Struct, 91 286-295.
CAN/CSA S806-02. (2002), Design and Construction of Building Components with Fibre Reinforced Polymers, Canadian Standards Association.
CEB-FIP Model Code 90. (1990), Model code for concrete structures, Comite Euro-International du Beton, Bulletin, 213-214.
JSCE (1997), Recommendation for design and construction of concrete structures using continuous fiber reinforcing materials, JSCE Concrete Engineeering Series 23.
Kim, S. E., and Kim, S. H. (2016), Finite Element Analysis of Beams with FRP Bars and Steel Bars, Conference Proceeding of Korea Concrete Institute, 28(2), 83-84.
Leung, H. Y., and Balendran, R. V. (2003), Flexural behaviour of concrete beams internally reinforced with GFRP rods and steel rebars, Structural Survey, 21(4), 146-157.
Shield, C., Galambos, T., and Gulbrandsen, P. (2011), On the History and Reliability of the Flexural Strength of FRP Reinforced Concrete Members in ACI 440.1R, 10th International Symposium on Fiber Reinforced Polymer Reinforcement for Concrete Structures, SP-275, American Concrete Institute, 1-18.
Soliman, S. M., El-Salakawy, E., and Benmokrane, B. (2011), Bond performance of near-surface mounted FRP bars, J Compos Constr, 15(1), 103-111.
Yang, J. M., Yoo, D. Y., Shin, H. O., and Yoon, Y. S. (2011), Flexural Strength and Deflection Evaluation for FRP Bar Reinforced HSC Beams with Different Types of Reinforcing Bar and Fiber, Journal of the Korea Concrete Institute, 23(4), 413-420.
Yoon, Y. S., Yang, J. M., Min, K. H., and Shin, H. O. (2011), Flexural strength and deflection characteristics of high-strength concrete beams with hybrid FRP and steel bar reinforcement, American Concrete Institute, SP275, 57-77.
Yost, J. R., Gross, S. P., and Dinehart, D. W. (2003), Effective moment of inertia for glass fiberreinforced polymer-reinforced concrete beams, ACI Struct. J., 100(6), 732-739.
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