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RISS 인기검색어
- 검색키워드
- 저자 : Yanshun Jia (검색결과 4 건)
- 무료
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Degradation reliability modeling of plain concrete for pavement under flexural fatigue loading
Jia, Yanshun,Liu, Guoqiang,Yang, Yunmeng,Gao, Ying,Yang, Tao,Tang, Fanlong Techno-Press 2020 Advances in concrete construction Vol.9 No.5
This study aims to establish a new methodological framework for the evaluation of the evolution of the reliability of plain concrete for pavement vs number of cycles under flexural fatigue loading. According to the framework, a new method calculating the reliability was proposed through probability simulation in order to describe a random accumulation of fatigue damage, which combines reliability theory, one-to-one probability density functions transformation technique, cumulative fatigue damage theory and Weibull distribution theory. Then the statistical analysis of flexural fatigue performance of cement concrete tested was carried out utilizing Weibull distribution. Ultimately, the reliability for the tested cement concrete was obtained by the proposed method. Results indicate that the stochastic evolution behavior of concrete materials under fatigue loading can be captured by the established framework. The flexural fatigue life data of concrete at different stress levels is well described utilizing the two-parameter Weibull distribution. The evolution of reliability for concrete materials tested in this study develops by three stages and may corresponds to develop stages of cracking. The proposed method may also be available for the analysis of degradation behaviors under non-fatigue conditions.
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Modeling of Chloride Ion Diffusion in Concrete under Fatigue Loading
Tao Yang,Bowen Guan,Guoqiang Liu,Yanshun Jia 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.1
It is common for reinforced concrete in the saline region to bear fatigue loading and chloride induced corrosion, which has become one of the main causes of structural failure of reinforced concrete. The objective of this paper is to investigate the characteristics of chloride ion transport in concrete under fatigue loading. A new theoretical model describing the chloride ion transport in saturated concrete under fatigue loading is proposed. In this model, the concrete is divided into two parts, matrix and microcrack, to characterize the chloride diffusion coefficient of concrete based on crack area. The influence of fatigue damage on the microcrack area of concrete is quantitatively analyzed and the relationship between fatigue loading and chloride diffusion coefficient is established. Then, based on Fick’s second law, the model is proposed and solved by analytical solution. Some experiments are conducted to verify the proposed model and the simulated and measured results are in good agreement with each other. Finally, the characteristics of chloride ion transport under different influencing factors are analyzed using the proposed model.
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Service life prediction of chloride-corrosive concrete under fatigue load
Yang, Tao,Guan, Bowen,Liu, Guoqiang,Li, Jing,Pan, Yuanyuan,Jia, Yanshun,Zhao, Yongli Techno-Press 2019 Advances in concrete construction Vol.8 No.1
Chloride corrosion has become the main factor of reducing the service life of reinforced concrete structures. The object of this paper is to propose a theoretical model that predicts the service life of chloride-corrosive concrete under fatigue load. In the process of modeling, the concrete is divided into two parts, microcrack and matrix. Taking the variation of mcirocrack area caused by fatigue load into account, an equation of chloride diffusion coefficient under fatigue load is established, and then the predictive model is developed based on Fick's second law. This model has an analytic solution and is reasonable in comparison to previous studies. Finally, some factors (chloride diffusion coefficient, surface chloride concentration and fatigue parameter) are analyzed to further investigate this model. The results indicate: the time to pit-to-crack transition and time to crack growth should not be neglected when predicting service life of concrete in strong corrosive condition; the type of fatigue loads also has a great impact on lifetime of concrete. In generally, this model is convenient to predict service life of chloride-corrosive concrete with different water to cement ratio, under different corrosive condition and under different types of fatigue load.
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Life-Cycle Reliability Evaluation of Semi-Rigid Materials Based on Modulus Degradation Model
Jiupeng Zhang,Shengchao Cui,Jun Cai,Jianzhong Pei,Yanshun Jia 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.6
The dynamic modulus of semi-rigid material is one of the important material parameters widely used in the design and evaluate ofasphalt pavement, which has a great effect on the reliability, healthy condition and service life of pavement. To show the three-phasedegradation process of dynamic modulus accurately and calculate the time-dependent reliability based on fatigue damage, thedegradation models based on non-linear fatigue damage and improved Wei-bull distribution modulus degradation are established andtestified in this paper, considering the threshold of normalized modulus. Then the reliability models based on the two abovedegradation process models are evaluated. Finally, the reliability analysis procedure is established using Monte Carlo (MC) methodand the corresponding calculation is conducted using Matlab. Cement stabilized macadam is used as an example in this paper. Results show that non-linear fatigue damage and improved Wei-bull distribution modulus degradation models can indicate threephasedegradation process of semi-rigid material modulus better and the reliability based on the proposed two models was moreaccurate to the actual situation.
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