Time step analysis of thermal stresses in concrete gravity dams

Distribution of thermal stresses in dams, especially concrete gravity dams is a complex and significant subject in designing the dams. Although by the use of a simplified assumption, the temperature distribution along the cross section of a dam can be considered linearly, because of the low thermal diffusion coefficient for concrete and variance of atmospheric conditions with time, temperature distribution along the dam cross section is nonlinear. So, the assumption of linear distribution of temperature will not be an accurate one. A number of factors influence the temperature distribution along the dam cross section that can be divided into two groups: internal factors due to hydration of cement and external factors due to atmospheric variation. The temperature distribution along the dam cross section has a significant effect on the thermal stresses. In the present paper a concrete gravity dam by the use of 2D finite element analysis in a climate condition similar to Mashhad were analyzed. In this analysis concreting in hot and cold weather with different types of cements (type I and type IV) were investigated. At the first step, the results of thermal analysis were obtained and then normal stresses and displacements at different nodes were extracted. The results show that the critical stresses are produced in the case of hot weather, with high thermal hydration for cement and high expansion coefficient for the materials. These stresses in the core of a dam cross-section and away from the drainage gallery and also adjacent to the toe and heel of the dam are maximum.