Factors influencing hysteresis characteristics of concrete dam deformation

Thermal deformation of a concrete dam changes periodically, and its variation lags behind the air temperature variation. The lag, known as the hysteresis time, is generally attributed to the low velocity of heat conduction in concrete, but this explanation is not entirely sufficient. In this paper, analytical solutions of displacement hysteresis time for a cantilever beam and an arch ring are derived. The influence of different factors on the displacement hysteresis time was examined. A finite element model was used to verify the reliability of the theoretical analytical solutions. The following conclusions are reached:(1) the hysteresis time of the mean temperature is longer than that of the linearly distributed temperature difference;(2) the dam type has a large impact on the displacement hysteresis time, and the hysteresis time of the horizontal displacement of an arch dam is longer than that of a gravity dam;(3) the reservoir water temperature variation lags behind of the air temperature variation, which intensifies the differences in the horizontal displacement hysteresis time between the gravity dam and the arch dam;(4) with a decrease in elevation, the horizontal displacement hysteresis time of a gravity dam tends to increase, whereas the horizontal displacement hysteresis time of an arch dam is likely to increase initially, and then decrease; and(5) along the width of the dam, the horizontal displacement hysteresis time of a gravity dam decreases as a whole, while the horizontal displacement hysteresis time of an arch dam is shorter near the center and longer near dam surfaces.