The paper deals with an impact of non–mechanical loads on the state of strength in massive concrete hydraulic structures. An example of hydroelectric plant subjected to the effect of water temperature annual fluctuation is considered. Numerical analysis of transient thermal–elasticity problem was performed. After determining the temperature distributions within the domain, the Duhamel-Neumann set of constitutive equations was employed to evaluate fields of mechanical quantities: displacement, strain and stress. The failure criterion proposed by Pietruszczak was adopted in assessing whether the load induces exceeding of strength of concrete within the structure volume. The primary finding is that the temperature effect can lead to damage of concrete in draft tubes and spirals, especially in winter months.