Chuanqing Fu

Modeling of Chloride Ions Diffusion in Cracked Concrete

In the saline environment, chloride ions diffusion depth in concrete is very important for predicting the service life of concrete structures. Moreover, concrete structures are not always crack-free. Cracks with different widths and depths will reduce the cover thickness and accelerate the migration of chloride ions. So, it’s significant to develop a model to predict the chloride diffusion depth in cracked concrete. In this research, the whole chloride diffusion process was divided into two parts: chloride diffusion in sound concrete and in crack. The solution concentration gradient existed in the crack obviously, and it changed the chloride concentration along the crack surface continually. Considering four factors that will influence the chloride diffusion in sound concrete, the diffusion model based on Fick’s second law was modified. And a FEM analysis on chloride diffusion in cracked concrete was performed with the new model in ANSYS. A good agreement can be found in comparison the numerical solution with test results. It proves that the new mathematic model is within a good accuracy in predicting the chloride diffusion depth in cracked concrete.

Risk Analysis of Tunnel Lining Using Fault Tree Theory and Entropy Measurement

Risk analysis of tunnel lining is a vital and complex problem. This paper presents a metrology for risk analysis of tunnel lining by employing Fault Tree Theory and Entropy Measurement. Some risk factors of tunnel lining are first identified. A lining fault tree analysis model is then established. Next, the entropy and entropy weight are applied to the risk analysis of tunnel lining. Finally, a definition of Lining Risk Entropy is put forward and the computational method and appraisal criterion are discussed.

Numerical Experiment on Flexural Properties of Steel Fiber Reinforced Concrete Beam

Based on the laboratory experiment of steel fiber reinforced concrete (SFRC), a total of 10 specimens have been designed according to the aggregate interface condition, steel fiber ratios and different-strength concrete. These specimens were computed by MFPA2D in micro-structure level. Comparing the result of SFRC with plain concrete beams, this paper validated the positive effect of steel fiber in crack-resistant and the flexural strength improvement of SFRC beam, analyzed the sensitivity of steel fiber to concrete with different strength, and provided the stress field and elastic modulus images. The numerical results gave the whole failure process of crack initiation, propagation, and interpenetrated. These results provide useful information toward understanding the flexural behavior of SFRC and have great significance to comprehend the flexural failure process of SFRC beam.