Papers by Author: Zhi Qiang Hu

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Authors: Ying Fang Fan, Zhi Qiang Hu, Jiang Lin Liu
Abstract: Deterioration of concrete exposed to acid rain environment will take a significant effect on the load carrying capacity and durability of the concrete structures. To evaluate the corrosion depth of concrete in acid rain environment, an experimental study was performed with ultrasonic wave technology in the laboratory. In the experiment, sulfate and nitric acid solutions are mixed to simulate the 3 pH levels (pH 3.5, pH 2.5 and pH 1.5) acid rain environments respectively. After being exposed to the simulated acid rain solutions for certain periods, a series of tests (including ultrasonic nondestructive test, Computerized Tomography (CT) test, compressive tests, etc.) were conducted. Damage depth, mass loss, axial compressive strength, and meso-structure of the concrete specimen under different corrosion state were achieved. It was shown that ultrasonic testing is a reliable nondestructive method to measure the damage depth of concrete. A bilinear regression model is proposed to predict the damage depth of concrete, which is in good correlation with testing results from both ultrasonic testing and CT test.
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Authors: Ying Fang Fan, Zhi Qiang Hu, Jing Zhou
Abstract: The structural behavior of an old six-span reinforced concrete arch bridge, which has been in service for about 40 years, is investigated. Field monitoring (inclusive of test of material property, static and dynamic test of the bridge) was conducted, static and dynamic responses of the bridge are obtained. Based on the primitive bridge, a scaled one-span bridge model was fabricated by organic-glasses. Both the static and dynamic tests were executed on the bridge model in the laboratory. Since the arch rib is the crucial member for the arch bridge, 7 notches were cut on both arch ribs of the bridge model to simulate different damages of the arch rib. Mechanical responses of the bridge with different damages on the arch ribs were achieved. FEM analyses were preformed on the bridge as well. Numerical results show good agreement with the experimental results.
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Authors: Tao Xu, Gao Lin, Chun An Tang, Zhi Qiang Hu
Abstract: The phenomenon creep fracture is well-known for concrete. In the present paper, the Material Failure Process Analysis (MFPA2D) model for concrete in the failure process is coupled in series with the time-dependence of the concrete damage and deformation. Further, the progressive creep failure of concrete specimens under constant tensile loading was numerically simulated and the typical time-dependent deformations: the transient creep, the steady-state creep and the accelerating creep were also represented. The numerical simulations indicate that the macroscopic creep failure is induced by clusters of micro-fractures on a mesocopic scale. The above numerical results offer us some theoretical indications and instructions to further investigate the instability failure mechanisms of engineering concrete structures in civil and hydraulic engineering.
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