Modelagem e monitoramento do comportamento térmico de fundações volumosas

Abstract

With the growth of the installation of wind farms in the Northeast region, driven by the potential of the region and by investments in search of a more sustainable energy matrix, there is a need to study the foundations of wind towers. These consist of mass concrete blocks that, due to their large volume, the exothermic reactions of cement hydration and the low capacity of concrete to dissipate heat, run the risk of reaching high temperatures, leading to the occurrence of pathological manifestations, especially thermal cracks and delayed ettringite formation. To avoid this, during the design phase, simulations must be carried out to estimate the heating and, during construction, measures must be taken to avoid reaching these harmful temperatures, which must be followed up by monitoring after construction. This work aims to contribute to the thermal modeling of these foundations, in order to help in the understanding of the internal phenomena that occur in these structures, evaluating the impact of different calorimetric profiles for the temperatures reached, improving the representation of the boundary conditions coming from the environment to evaluate their impact on heat exchange. Finally, based on data from real foundations, considerations were made about the phenomena of heat exchange between the structure and the surroundings, and how environmental factors exert their influence. A three- dimensional model of the foundation geometry was made for transient thermal analysis, and from it, parametric studies were performed, changing the calorimetry curve, wind speed and ambient temperature. Then, data from real structures built in different environments were compared to corroborate the simulation results. Thus, relationships for predicting the behavior of foundation temperatures were obtained from the calorimetric curves of the binder, an analysis of climatic conditions and their impact on heat exchanges, in addition to considerations on the thermal gradients formed in the foundation. The case study supported the difference caused by considering the climatic conditions in a more realistic way, served as a parameter for comparison with the simulations and showed the difference in the cooling of structures in different environments.