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Temperature Effect of Concrete Hydration Heat under Atmospheric Wind Based on Fluid-Solid Coupling
Moyan Zhang,Hong Xiao,Meng Wang,Mahantesh M. Nadakatti,Peng Chen 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.3
Concrete inevitably gets subjected to the effects of atmospheric wind during pouring. It is a significant factor to predict the temperature stress and gradient of concrete structure during pouring. In this paper, the Computational Fluid Dynamics (CFD) and Finite Element Method (FEM) were used to analyze the temperature and stress generated by temperature gradient of mass cap concrete under the wind environment. Then, the reliability of the temperature value was verified by the field test. The analysis shows that the use of the fluid-solid coupling method allows considering not only the thermal movement and thermodynamic properties of wind (given by CFD), but also the thermal expansion and stress of the concrete structure (given by FEM). Because of the wind, temperature of the windward side of the concrete is lower than that of the leeward side. Highest temperature is located at the center biased towards the leeward side. Increase in the wind speed increases the temperature difference and the maximum principal tensile stress. However, the study shows that change in the wind direction has limited effect on the concrete temperature stress.
Moyan Zhang,Hong Xiao,Jiaqi Wang,Shuwei Fang,Ziqing Jiang 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.8
Excessive fastener spacing, which results from construction errors (the bridge construction error and the track layout error) and environment temperature, is a possible safety risk for train and track structure. To address this problem, this paper selected a CRTSIII ballastless track-bridge section as the engineering case, and established a thermal-mechanical trackbridge coupling model. The maximum fastener spacing was calculated based on the model, and the dynamic and static characteristics of train and track under the different fastener spacing were compared. The results show that under the combination of construction errors and ambient temperature, the most unfavorable fastener spacing is 755 mm; with the increase in fastener spacing, the longitudinal resistance of fasteners first reaches the limit in the static safety indexes; the rail vertical dynamic displacement first reaches the limit in the dynamic safety indexes. Therefore, maximum fastener spacing of CRTSIII ballastless track structure depends on railway operation and maintenance, train speed and local environment.