• Steel and Composite Structures
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• 제32권4호
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• pp.537-548
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• 2019

This paper introduces an improved numerical model which can consider the bond-slip effect in steel-concrete composite structures without taking double nodes to minimize the complexity in constructing a finite element model. On the basis of a linear partial interaction theory and the use of the bond link element, the slip behavior is defined and the equivalent modulus of elasticity and yield strength for steel is derived. A solution procedure to evaluate the slip behavior along the interface of the composite flexural members is also proposed. After constructing the transfer matrix relation at an element level, successive application of the constructed relation is conducted from the first element to the last element with the compatibility condition and equilibrium equations at each node. Finally, correlation studies between numerical results and experimental data are conducted with the objective of establishing the validity of the proposed numerical model.

• 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.

• 콘크리트학회지
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• 제6권4호
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• pp.92-101
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• 1994

PS 강선의 정착부착성능에 대한 새로운 해석방법을 소개하였다. 이 모델에서, 정착부착 길이는 탄생 영역과 소성영역으로 구분되었다. 탄성영역에서 부착응력은 최대 부착응력에 도달된 때까지 슬립과 비례하여 증가하고, 소성영역에선 최대 부착응력으로 균일하게 분포됨을 가정하였다. 정착부착 길이 내에서 부착응력, 슬립, 강선응력, 콘크리트응력 분포를 결과를 얻을 수 있었고, 전체 정착부착 길이와 자유단에서 슬립에 대한 결과치는 최근 Cousins et al.의 실험 결과치와 유사하였다.

• 대한토목학회논문집
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• 제29권5A호
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• pp.495-501
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• 2009

본 논문에서는 앵커로 연결된 콘크리트-강재 구조물이 극한 반복주기하중을 받는 경우를 수치 시뮬레이션하기 위하여 필요한 콘크리트-앵커 부착모형에 대하여 논하였다. 제안되는 앵커의 부착-미끄러짐 수치모형은 비선형 일축 연결요소의 조합으로 이루어지며 인발실험 결과를 이용하여 부착-미끄러짐 모형의 인자를 결정할 수 있다. 제안된 앵커 부착-미끄러짐 모형을 Abaqus 요소의 조합으로 구성하고, 이를 사용한 해석 결과와 앵커의 완전부착모형을 사용한 해석 결과를 실험 결과와 비교하였다. 이로부터 극한 반복하중을 받는 콘크리트-강재 구조물 수치해석에는 합리적인 앵커 부착-미끄러짐 모형이 반드시 사용되어야 한다는 것을 알 수 있었으며 본 연구에서 제안한 합성 연결모형을 이용하면 사실적으로 앵커의 부착-미끄러짐 현상을 모사할 수 있다는 것을 확인하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.853-858
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• 2003

A new method is proposed to obtain bond-slip model for an adhesive joint between FRP and concrete. Interface element, which can describe the bond behavior, is developed in order to overcome the restriction that complex constitutive relations cannot be modeled in analytic solution. Calibrating numerical bond-slip model to experimental results, multi-objective optimization problem is constructed by physical programming method, and is solved using genetic algorithm. The validity of proposed method is demonstrated by comparing known analytic solution and numerically optimized solution.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.309-312
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• 2006

An experimental study for bond slip behavior of concrete and a FRP plank was used as the both formwork and the tensile reinforcement for a concrete structural member is described. For the FRP plank and the concrete to act as a composite structural member a satisfactory bond at the interface between the smooth surface of the FRP and the concrete must be developed. This study focuses on investigation of the bond slip behavior of sand coated interface between FRP and cast-in-place concrete experimentally.

• Structural Engineering and Mechanics
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• 제26권5호
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• pp.569-589
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• 2007

This paper presents an analytical model for RC beam-column connections that takes into account bond deterioration between reinforcing steel and concrete. The model is based on the Lumped Damage Mechanics (LDM) theory which allows for the characterization of cracking, degradation and yielding, and is extended in this paper by the inclusion of the slip effect as observed in those connections. Slip is assumed to be lumped at inelastic hinges. Thus, the concept of "slip hinge", based on the Coulomb friction plasticity theory, is formulated. The influence of cracking on the slip behavior is taken into account by using two concepts of LDM: the effective moment on an inelastic hinge and the strain equivalence hypothesis. The model is particularly suitable for wide beam-column connections for which bond deterioration dominates the hysteretic response. The model was evaluated by the numerical simulation of five tests reported in the literature. It is found that the model reproduces closely the observed behavior.

• 대한토목학회논문집
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• 제26권2A호
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• pp.285-292
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• 2006

이 연구는 탄소섬유쉬트-콘크리트 부착이음 실험 결과로부터 국부적인 부착모텔(부착응력-미끄럼 모델)을 결정하는 방법을 제안하고, 실제 실험 결과와 비교하여 이러한 부착 조건에 적용 기능한 부착모델을 제시한다. 부착모델의 형상은 임의의 곡선 형태를 고려할 수 있도록 디중선형곡선(multi-linear curve)으로 가정하였으며, 수치적인 방법으로 부착이음의 해를 계산하여 실험 결과와 오차를 최소화하는 방법으로 부착모델을 결정하였다. 이중선형곡선(bilinear curve)을 도입한 부착모델 역시 최적화를 수행하여 다중선형모텔과 비교하였다. 최적화의 대상은 동일 조건의 부착모텔에 대해 여러 실험체로부터 구한 극한하중-부착길이 곡선과 개별 실험체의 하중-변위 곡선이다. 최적화를 위한 정식화는 physical programming을 사용하였으며 최적화 방법은 유전알고리즘(genetic algorithm)을 이용하였다.

• Structural Engineering and Mechanics
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• 제74권5호
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• pp.589-600
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• 2020

The bonding interface of the concrete slab track and cement-asphalt mortar layer plays an important role in transferring load and restraining the track slab's deformation for slab track structures without concrete bollards in high-speed railway. However, the interfacial bond-slip behavior is seldom considered in the structural analysis; no credible constitutive model has been presented until now. Elaborating the field tests of concrete to cement-asphalt mortar interface subjected to longitudinal and transverse shear loads, this paper revealed its bond capacity and failure characteristics. Interfacial fractures all happen on the contact surface of the concrete track slab and mortar-layer in the experiments. Aiming at this failure mechanism, an interfacial mechanical model that employed the bilinear local bond-slip law was established. Then, the interfacial shear stresses of different loading stages and the load-displacement response were derived. By ensuring that the theoretical load-displacement curve is consistent with the experiment result, an interfacial bond-slip constitutive model including its the corresponding parameters was proposed in this paper. Additionally, a finite element model was used to validate this constitutive model further. The constitutive model presented in this paper can be used to describe the real interfacial bonding effect of slab track structures with similar materials under shear loads.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.917-922
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• 2002

This paper deals with the estimation of the maximum crack widths considering bond-slip relationships based on experimental data that were tensed by axial force. It is certificated that the concrete stress condition clearly affects the bond-slip relationship. The proposed method utilizes the conventional crack and bond-slip theories as well as the characteristics of deformed reinforcement and size effects. An analytical equation for the estimation of the maximum flexural crack width is formulated as a function of minimum crack length and the coefficient of bond stress effect. The validity, accuracy and efficiency of the proposed method are established by comparing the analytical results with the experimental data and the major specifications (e.g., ACI, CEB-FIP Model code, Turocode 2, JSCE, etc.). The analytical results presented in this paper indicate that the proposed method can be effectively estimated the maximum flexural crack width of reinforced concrete.