• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.519-526
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• 1997

The purpose of this study is to develop the analytical model for the reinforcement bar connection in group-filled steel pipe sleeve, which consists of beam elements for the reinforcement bar and shell elements for the sleeve and the mortar and spring elements for the bond stress-slip relationship. In the reinforcement bar connection using grout-filled steel pipe sleeve, the major variables are the bond stiffness between reinforcement bar and mortar($K_1$) and between sleeve and mortar($K_2$). It is nearly difficult to predict the exact bond stiffness with the experimental results. Therefore, The linearly elastic analyses using ABAQUS, FEM package show the validity of the mathematical equations for the bond stiffness and the choice of material elements in this paper. To predict the behaviour between yield and ultimate tensile strength, the nonlinear analyses must be performed henceforth.

• Structural Engineering and Mechanics
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• 제78권2호
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• pp.199-207
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• 2021

In the present paper, an analytical model is proposed to determine the flexural and shear strength of normal and high-strength reinforced concrete beams with longitudinal bars, in the presence of transverse stirrups. The model is based on evaluation of the resistance contribution due to beam and arch actions including interaction with stirrups. For the resistance contribution of the main bars in tension the residual bond adherence of steel bars, including the effect of stirrups and the crack spacing of R.C. beams, is considered. The compressive strength of the compressed arch is also verified by taking into account the biaxial state of stresses. The model was verified on the basis of experimental data available in the literature and it is able to include the following variables in the resistance provision: - geometrical percentage of steel bars; - depth-to-shear span ratio; - resistance of materials; - crack spacing; - tensile stress in main bars; - residual bond resistance including the presence of stirrups;- size effects. Finally, some of the more recent analytical expressions able to predict shear and flexural resistance of concrete beams are mentioned and a comparison is made with experimental data.

• Structural Engineering and Mechanics
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• 제26권2호
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• pp.211-229
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• 2007

An experimental investigation to determine the transfer length of a seven-wire prestressing strand in different concretes is presented in this paper. A testing technique based on the analysis of bond behaviour by means of measuring the force supported by the prestressing strand on a series of specimens with different embedment lengths has been used. An analytical bond model to calculate the transfer length from an inelastic bond stress distribution along the transfer length has been obtained. A relationship between the plastic bond stress for transfer length and the concrete compressive strength at the time of prestress transfer has been found. An equation to predict the average and both the lower bound and the upper bound values of transfer length is proposed. The experimental results have not only been compared with the theoretical prediction from proposed equations in the literature, but also with experimental results obtained by several researchers.

• Structural Engineering and Mechanics
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• 제54권2호
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• pp.319-336
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• 2015

Life cycle performance of corrosion affected RC structures is an important and challenging issue for effective infrastructure management. The accurate condition assessment of corroded RC structures mainly depends on the effective evaluation of deterioration occurring in the structures. Structural performance deterioration caused by reinforcement corrosion is a complex phenomenon which is generally uncertain and non-decreasing. Therefore, a stochastic modelling such as the gamma process can be an effective tool to consider the temporal uncertainty associated with performance deterioration. This paper presents a time-dependent reliability analysis of corrosion affected RC structures associated bond strength degradation. Initially, an analytical model to evaluate cracking in the concrete cover and the associated loss of bond between the corroded steel and the surrounding cracked concrete is developed. The analytical results of cover surface cracking and bond strength deterioration are examined by experimental data available. Then the verified analytical results are used for the stochastic deterioration modelling, presented here as gamma process. The application of the proposed approach is illustrated with a numerical example. The results from the illustrative example show that the proposed approach is capable of assessing performance of the bond strength of concrete structures affected by reinforcement corrosion during their lifecycle.

• 한국안전학회지
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• 제28권2호
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• pp.55-59
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• 2013

The analytical model was constituted to evaluate the flexural strength of UHPFRC(ultra high performance fiber reinforced concrete) member. The analytical approach was attemped to study the effect of the joint and the result compared with the experimental study to verify the analytical model. The calculated value tends to underestimate about 23%~25% in comparison with the experimental result of the jointed test member because the bond stress between precast UHPFRC and cast-in-place UHPFRC surface is not considered in the analytical model. But in the case of the continuous test member, the analytical model provides reasonable results for the flexural strength of UHPFRC member.

• 한국구조물진단유지관리공학회 논문집
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• 제10권3호
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• pp.143-151
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• 2006

본 논문은 철근 또는 GFRP 보강근과 콘크리트 사이의 해석적 부착모델에 관한 적합성에 대해 기술하였다. 부착시편은 CSA 규준에 따라 제작하여 실험하였으며, 실험에 사용된 보강근의 종류는 철근과 상용화된 GFRP 보강근 2종(ASLAN, ISOROD)이다. 실험결과를 이용하여 새로운 부착모델을 제안하였으며, 기존 연구자들이 제안한 해석적 부착모델과 새롭게 제안된 부착모델의 적합성을 최소자승법을 통해 검토하였다. 검토결과 새롭게 제안된 해석적 부착모델은 기존 부착모델에 비해 높은 적합성을 나타내었다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 봄 학술발표회 논문집
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• pp.267-274
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• 2001

In this paper, a analytical model which can simulate the post-cracking behavior and tension stiffening effect in a reinforced concrete(RC) tension member is proposed. Unlike the classical approaches using the bond stress-slip relationship or the assumed bond stress distribution, the tension stiffening effect at post-cracking stage is quantified on the basis of polynomial strain distribution functions of steel and concrete, and its contribution is implemented into the reinforcing steel. The introduced model can be effectively used in constructing the stress-strain curve of concrete at post-cracking stage, and the loads carried by concrete and by reinforcing steel along the member axis can be directly evaluated on the basis of the introduced model. In advance, the prediction of cracking loads and elongations of reinforced steel using the introduced model shows good agreements with results from previous analytical studies and experimental data.

• 한국전산구조공학회논문집
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• 제19권1호
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• pp.1-13
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• 2006

이 논문에서는 적층단면법에 기초하여 단조하중 또는 반복하중을 받는 철근콘크리트 보 및 기둥 부재의 비선형 해석모델이 제안되었다. 완전부착 가정을 토대로 하고 있는 적층단면법은 콘크리트와 철근 사이의 부착슬럽 거동을 고려하지 못한다는 고전적 비선형 해석법과는 달리, 균열 발생시 철근을 따라 발생되는 부착슬립 거동을 힘의 평형관계와 변위의 적합조건으로 정량화하고, 그 결과로부터 철근의 강성을 보정해줌으로써 반영하도록 하였다. 이는 적층단면법에서 추가 자유도(double node)를 도입하지 않고 부착슬립효과를 고려할 수 있다는데 그 의의를 둘 수 있을 것이다. 나아가 제안된 방법에 의한 해석결과와 실험결과와의 비교를 통해, 제안된 방법은 부착슬립 거동에 의한 강성저하(stiffness degradation)를 동반하는 철근콘크리트 보 및 기둥 부재의 균열거동을 효과적으로 고려할 수 있음을 검증하였다

• 한국산학기술학회논문지
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• 제21권9호
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• pp.414-423
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• 2020

최근 콘크리트 구조물을 보강하는데 경량이며 높은 강도를 가지고 있는 FRP(Fiber Reinforced Polymer)시트의 사용이 증가하고 있는데 구조물 보강 설계 시 부착 강도가 매우 중요하다. 그래서 FRP시트와 콘크리트 사이의 부착 강도에 대한 정확한 수치 모델을 얻기 위하여 많은 연구자가 다양한 변수(콘크리트 압축강도 및 인장강도, 콘크리트와 FRP의 탄성계수, 콘크리트와 FRP의 폭과 두께, 파괴에너지, 부착 길이, 유효부착길이, 최대 부착 응력과 최대 슬립)를 가지고 실험과 해석 연구를 수행하여 왔다. 결과적으로 많은 모델이 도출되었으나 실무에 쉽게 사용될 수 있는 검증된 모델은 제시되지 않았다. 그래서 본 연구는 현재까지 제안된 23개의 모델(Khalifa 모델, Iso 모델, Maeda 모델, Chen 모델 등)로부터 부착 강도에 미치는 요인을 분석하고 188개의 시험체에 대한 부착 강도 실험값을 각 모델들의 수치 결과 값과 비교하여 수식이 간단하고 높은 정도를 가진 사용하기 쉬운 모델을 제시하고자 하였다. 결과적으로 부착 강도 모델로 Iso 모델과 Holzenkӓmpfer 모델의 유효부착길이에 근거한 실용성 있는 모델을 제안하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 추계 학술발표회 제17권2호
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• pp.197-200
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• 2005

This paper presents an analytical model for evaluation of Tension Stiffening Effect by actual Bond-Slip relationships between the reinforcement and the surrounding concrete. The presence of longitudinal splitting cracks was found to significantly after the tension stiffening. The model is applied to the longitudinal splittings cracks and derived to Tension stiffening model. The predicted values are shown to be in good agreement with the experimentally measured data.