1. State Key Laboratory of Water Resources and Hydropower Engineering, Wuhan University, Wuhan 430072, China 2. College of Civil Engineering and Architecture, Zhejiang University of Technology, Hangzhou 310014, China
Previous studies have shown that the thermal expansion coefficient of concrete has obvious age-dependent characteristic. An experiment based on temperature-stress testing machine was designed to measure the thermal expansion coefficient, in order to study the time-varying characteristic of the thermal expansion coefficient of concrete and its effect on the thermal stress simulation, and to simulate the early-age temperature stress of concrete more accurately. The concept about the equivalent age was introduced. The temperature deformation and self-grown volume deformation were separated successfully. A mathematical model between the thermal expansion coefficient and the equivalent age was established. The rationality of this model was verified through the simulation of the laboratory test. Additionally, the effect of time-varying thermal expansion coefficient on temperature-stress simulation was discussed through the simulation of temperature-stress of Dagangshan super high arch dam. Results showed that the coefficient of thermal expansion of concrete changed greatly in early age. Considering the time-varying property of the coefficient of thermal expansion is significant for simulation and crack prevention. The simulated stress level calculated by considering the time-varying effect was higher than that of the traditional method, especially for the concrete with fast temperature drop rate at early age due to water flow. It is safer to carry out crack prevention design according to the new method.
Fig.11Maximum first principal stress envelope diagram of foundation restraint area
Fig.12Maximum first principal stress envelope diagram of non-constrained area
Fig.13History curve of temperature and stress within 28 days after concrete pouring
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