Results of the conducted research aiming to demonstrate the methodology of optimization of dam monolith length (distance between contraction joints), through monitoring the thermal tensile stresses during construction and service life of a concrete gravity dam that is built using the block method, are presented in this paper. A 3D space–time numerical model for phased thermal stress analysis is employed in a large concrete gravity dam case study. For the adopted block dimensions, schedule, and dynamics of construction and material parameters, the thermal stress analysis is conducted, taking into account the following: thermal physical properties of the material, the cement hydration process, heat exchange with the external environment and the reservoir, and self-weight of the structure. The main advantage of the proposed methodology is the possibility of controlling the cracks resulting from thermal tensile stresses in the monolith of a concrete gravity dam, by optimizing the monolith’s length to minimize the zones in which the tensile capacity of concrete is exceeded. The results obtained from the temperature field analysis show that the maximum temperature increase in the dam’s body results from the cement hydration process in combination with summer air temperatures in the construction phase. The aforementioned factors account for the increase in temperature of up to 45.0 °C, while during winter cooling of the structure occurs due to lower temperatures, especially in the surface zones. The results of the stress field analysis show that the extreme values of thermal tensile stresses are present in the process of a sudden or gradual cooling of the concrete when shrinkage occurs. Finally, it is shown that the reduction of the monolith length by 5.0 m (from 20.0 m to 15.0 m) results in a decrease in the extreme thermal tensile stress values by an average of 0.70 MPa (up to 12.0%) in winter and an average of 1.10 MPa (up to 20.0%) in summer; while for the entirety of the analyzed time period, results in a decrease in the extreme thermal tensile stress values by an average of 16.0% (0.93 MPa).

Additional temperature stresses in continuously welded rails (CWRs) are caused by track/bridge interaction (TBI) due to thermal actions. Exceeding permissible stresses in CWRs on the bridge can lead to track buckling or rail cracking, compromising the safety of railway traffic. The main aim of the conducted study is to determine the effects of the key parameters such as rail cross-sectional area, track longitudinal resistance, bridge expansion length, and longitudinal stiffness of the fixed bridge support on the reduction of additional temperature stresses in CWRs on steel truss railway bridges. To quantify the effects of these parameters, two steel railway bridges with CWRs and the maximum expansion lengths according to UIC Code 774-3 were analyzed: (1) simply supported truss bridge with expansion length of 60 m and (2) continuous truss bridge with expansion lengths of 2 × 60 m. According to the obtained results, the track longitudinal resistance had the most significant impact on additional temperature stresses in CWRs, leading to their reduction of up to 72%. The bridge expansion length and the rail cross-sectional area led to reductions of up to 25% and up to 18%, respectively. Considering the deformation criteria of TBI, the longitudinal stiffness of the fixed bridge support had a minor effect on the reduction of additional temperature stresses in CWRs.

This paper examines the influence of monolith length on the temperature field of concrete gravity dams built using the block method. The developed 3D model is capable of conducting a thermal analysis of a 95.0 m high concrete gravity dam built using the block method, where each newly cast block represents a new analysis phase. The calculation accounts for the period of construction, the filling of the reservoir, and the service for a total duration of about 5 years. The thermal properties of the material, the influence of cement hydration heat, the temperature of the surrounding rock mass, the temperature of the fresh concrete mixture, and the corresponding boundary conditions defining a heat transfer were taken into account. The height and width of the blocks, as well as the sequence of concreting, were considered invariable, while the length of the blocks (dimension in the direction of the dam’s axis equal to the monolith length) varied, with values of 10.0, 12.5, 15.0, and 20.0 m. The obtained calculation results for the control nodes showed that the maximum reduction in the monolith length (from 20.0 m to 10.0 m) caused a decrease in the maximum temperature values of the concrete (from 1.6 to 3.4 °C, depending on the control node). Also, the results showed that, by reducing the length of the monolith, there was a delay in the moment at which the maximum temperature values of the concrete appeared in the selected control node. The delay in reaching the maximum, in relation to the 10.0 m long monolith, was from 7 days (for points on the crest dam) to 49 days (for points in the central zone of the monolith) for the other considered monolith lengths. The above indicates the importance of concrete temperature control for longer monoliths, especially during construction in extreme air temperatures. The main contribution of the conducted analysis is the development of insight into temperature field changes depending on monolith length, which can help engineers during the design and construction of new, as well as the maintenance of existing, dams.

The analysis of the dynamic interaction between the train, track, and bridge is crucial for ensuring the performance of railway infrastructure and the safety of railway traffic, especially on high-speed rail systems. This paper examines the key requirements for analyzing the dynamic interaction between the train, track, and bridge, with particular emphasis on the guidelines outlined in UIC Code 776-2. The analysis includes the structural strength of the bridge, passenger comfort, and the overall safety of railway traffic, ensuring a comprehensive evaluation of the entire railway system. Specifically, the paper examines the impact of continuously welded rails, which are widely used in modern railways due to their improved performance and reduced maintenance needs. The dynamic behavior of the train, track, and bridge is analyzed to confirm the structural integrity of the system, mitigate vibrations, and enhance passenger comfort. UIC Code 776-2 serves as a key reference for understanding the design and performance requirements for analyzing train-track-bridge dynamic interaction, guaranteeing that safety standards are met while optimizing efficiency. By evaluating the dynamic performance of the train, track, and bridge components, potential risks can be assessed, and strategies can be developed to mitigate them. This research contributes to the development of more resilient railway systems, ensuring the safety of both passengers and infrastructure.

This study investigates the sensitivity of additional temperature stresses in continuously welded rails on a bridge, using a railway viaduct with a span of 10×30 m as an example. The aim of the analysis is to quantify the influence of track longitudinal resistance on the distribution of temperature stresses arising from the thermal track/bridge interaction. Track longitudinal resistance represents a key parameter in the behavior of continuously welded rails on a bridge. Numerical models were developed using the finite element method, and the calculations were performed in accordance with relevant European standards and guidelines, including UIC Code 774-3. The study examined track longitudinal resistance under summer and winter conditions, the application of reduced resistances in rail fastening systems, as well as the ZLR (Zero Longitudinal Restraint) system. Special attention was given to the influence of these variations on the control of track lateral stability in summer conditions, as well as on the control of rail break gap in winter conditions. Both checks are of critical importance for railway safety. The results show that variations in track longitudinal resistance cause significant changes in the distribution of temperature stresses, highlighting the need for careful design and optimization of track components on a bridge. The findings contribute to a better understanding of thermal track/bridge interaction and provide a basis for improving the design of railway viaducts with continuously welded rails.

Wind turbine foundations are massive concrete structures in which controlling the temperature rise during the early-age curing process is of crucial importance for preventing cracking caused by thermal tensile stresses and for ensuring the durability of the concrete structure. This paper presents an example of a thermal analysis of three massive wind turbine foundations within a wind farm in the Republic of Serbia, based on the application of the finite element method. The thermal analysis included all relevant aspects of the thermal behavior of concrete-material parameters, boundary conditions, and construction dynamics. Variations in the initial temperature of the concrete mixture were considered in order to predict peak temperatures during the cement hydration process. The calculations were performed in accordance with relevant European and international standards and guidelines, including Eurocode and ACI. The results indicate exceedance of the peak temperatures prescribed by the regulations and the necessity of applying appropriate measures to reduce the temperature in the concrete. The obtained conclusions contribute to a better understanding of the presented thermal processes and emphasize the necessity of implementing measures to reduce peak temperatures in concrete. Exceeding peak temperatures, followed by long-term cooling and shrinkage of massive structures (toward the average ambient temperature), may cause the formation and development of cracks that negatively affect the quality and durability of massive concrete wind turbine foundations.