Corrosion of reinforcement has a significant effect on the deformation of reinforced concrete beams by deteriorating the bond-slip characteristics, diminishing the cross-sectional area of reinforcement, and causing cr...Corrosion of reinforcement has a significant effect on the deformation of reinforced concrete beams by deteriorating the bond-slip characteristics, diminishing the cross-sectional area of reinforcement, and causing cracking. The traditional way of quantifying the load capacity and simulating deflection is the moment-curvature(M/χ) approach. The problem is that the M/χ approach is semi-empirical after cracking as it is strain-based and cannot allow for tension stiffening. This paper introduces the new displacement-based moment-rotation(M/θ) approach which directly simulates the development of cracks and hence allows for tension stiffening. This M/θ approach is then used to predict the load-deflection behavior of reinforced concrete beams with corrosion effect by incorporating the corrosion-affected bond-slip model. The bond-slip model only considers the corrosion effect but ignores the confinement effect. It is used here as an example to describe the procedure of how to quantify the corrosion effect on reinforced concrete beam behavior. The load-deflection curves obtained from the numerical simulation show a good agreement with test results. For reinforced concrete beams with confinement, the only difference is to replace the bond-slip model with the one which includes both corrosion and stirrup effects. Additionally, the paper shows how to use the M/θ approach with the bond-slip model to predict the real corrosion level of reinforcement in some tests in which only the theoretical corrosion levels are provided.展开更多
In this article, the composite π-joint is investigated under bending loads. The ＂L＂ preform is the critical component regard- ing composite π-joint failure. The study is presented in the failure detection of a car...In this article, the composite π-joint is investigated under bending loads. The ＂L＂ preform is the critical component regard- ing composite π-joint failure. The study is presented in the failure detection of a carbon fiber composite π-joint structure under bending loads using fiber Bragg grating （FBG） sensor. Firstly, based on the general f＇mite element method （FEM） software, the 3-D finite element （FE） model of composite π-joint is established, and the failure process and every lamina failure load of composite π-joint are investigated by maximum stress criteria. Then, strain distributions along the length of FBG are extracted, and the reflection spectra of FBG are calculated according to the strain distribution. Finally, to verify the numerical results, a test scheme is performed and the experimental spectra of FBG are recorded. The experimental results indicate that the failure sequence and the corresponding critical loads of failure are consistent with the numerical predictions, and the computational error of failure load is less than 6.4%. Furthermore, it also verifies the feasibility of the damage detection system.展开更多
基金Project supported by the National Natural Science Foundation of China(No.51478422)。
文摘Corrosion of reinforcement has a significant effect on the deformation of reinforced concrete beams by deteriorating the bond-slip characteristics, diminishing the cross-sectional area of reinforcement, and causing cracking. The traditional way of quantifying the load capacity and simulating deflection is the moment-curvature(M/χ) approach. The problem is that the M/χ approach is semi-empirical after cracking as it is strain-based and cannot allow for tension stiffening. This paper introduces the new displacement-based moment-rotation(M/θ) approach which directly simulates the development of cracks and hence allows for tension stiffening. This M/θ approach is then used to predict the load-deflection behavior of reinforced concrete beams with corrosion effect by incorporating the corrosion-affected bond-slip model. The bond-slip model only considers the corrosion effect but ignores the confinement effect. It is used here as an example to describe the procedure of how to quantify the corrosion effect on reinforced concrete beam behavior. The load-deflection curves obtained from the numerical simulation show a good agreement with test results. For reinforced concrete beams with confinement, the only difference is to replace the bond-slip model with the one which includes both corrosion and stirrup effects. Additionally, the paper shows how to use the M/θ approach with the bond-slip model to predict the real corrosion level of reinforcement in some tests in which only the theoretical corrosion levels are provided.
基金supported by the National High Technology Research and Development Program of China (No.2007AA03Z117)the Key Program of National Natural Science of China (No.50830201)the Ph.D. Teacher,s Research Project of Xuzhou Normal University
文摘In this article, the composite π-joint is investigated under bending loads. The ＂L＂ preform is the critical component regard- ing composite π-joint failure. The study is presented in the failure detection of a carbon fiber composite π-joint structure under bending loads using fiber Bragg grating （FBG） sensor. Firstly, based on the general f＇mite element method （FEM） software, the 3-D finite element （FE） model of composite π-joint is established, and the failure process and every lamina failure load of composite π-joint are investigated by maximum stress criteria. Then, strain distributions along the length of FBG are extracted, and the reflection spectra of FBG are calculated according to the strain distribution. Finally, to verify the numerical results, a test scheme is performed and the experimental spectra of FBG are recorded. The experimental results indicate that the failure sequence and the corresponding critical loads of failure are consistent with the numerical predictions, and the computational error of failure load is less than 6.4%. Furthermore, it also verifies the feasibility of the damage detection system.
