## 1 Introduction  
Immediately upon pouring the concrete, the temperature in the body of a concrete gravity dam (CGD) rises [1; 2; 3; 4]. As a consequence of the cooling of concrete, thermal dilatations initiate a change in the volume of the structure [2; 3; 5; 6]. If the volumetric deformations are restrained or limited, this leads to the formation of thermal tensile stresses (TTS), which can eventually cause cracking in the structure [1; 2; 3]. Cracks tend to expand over time, reducing the dam's capacity, enabling water penetration, and the increase in uplift forces [3; 4; 7; 8]. Numerous researchers have dealt with the thermal analysis of concrete dams [9; 10; 11; 12; 13; 14; 15]. [PERSON] and [PERSON] [16] conducted thermal stress analysis (TSA) of a concrete arch dam, taking into account the hydration heat for every freshly poured concrete block, phased change of the boundary conditions in the model, as well as crack development, but not including the impact of changes to the blocks' dimensions on the crack formation process. [PERSON] et al. [17] simulated the construction process of a CGD made of roller compacted concrete (RCC), which is built in layers. TSA was conducted for different monolith lengths (15, 30, and 45 m), accounting for the hydrostatic pressure on the upstream face, which distorted the field of TTS (which exclusively occurs as a consequence of thermal processes in the structure). [PERSON] and [PERSON] [18] analyzed stresses in a concrete arch dam taking into account all the relevant thermal processes, self-weight of the structure, and hydrostatic pressure, which, as shown in the previous paper, does not provide a clear insight into TTS which are exclusively a consequence of thermal processes in the structure. [PERSON] et al. [19] conducted coupled chemo-thermal 3D analysis of a concrete arch dam and simulated hydration heat based on test results carried out during construction. [PERSON] et al. [20] analyzed the relevance of a correct calculation of the reference temperature to adequately determine the stress state of the arch dam. [PERSON] et al. [21; 22] presented a methodology for calculating the monolith length of CGD Platanovrysssi (Greece) made of RCC. In [21; 22], the authors acknowledged all the relevant thermal processes along with the self-weight of the structure and described the realistic TTS field in the structure. The developed model is applicable with CGD made of RCC in which the placing of concrete is executed in layers up to 1 m thickness, as opposed to the model presented in this paper where the construction process is simulated on the same CGD by using the block method (TSA in case of changing construction technology). [PERSON] et al. [23] conducted coupled TSA of a CGD taking into account the relevant thermal processes, and experimental and analytical models of the authors [24] for model verification. The conducted analysis did not take into account the impact of different monolith lengths on the stress field (SF) in the dam's body. Thermal stresses can present a big issue in many engineering topics, as well as additive manufacturing and other manufacturing processes [25; 26; 27; 28]. Exceedance of concrete tensile resistance resulting from TTS occurs in the dam's axis direction. This causes cracks in the vertical plane, through the height of the dam's cross-section. Crack width and spacing between the adjacent cross-sections in which they occur depend on the degree of restraint against the change of volume; this is a function of the environment in which the foundation of the dam is cast, adjacent structures which are in contact with the dam, as well as previously cast concrete blocks [1]. Given possible consequences that damaging or eventual collapse of these types of objects [29] would have on the environment, it is customary to limit and sustain TTS below the concrete tensile resistance which is, for concrete class from C20/25 to C40/50, in the range from 2.2 to 3.5 MPa [5].