Desenvolvimento de mapas de temperatura para a aplicação em projetos de obras de artes especiais como contribuição a revisão da NBR6118

Abstract

In Brazil, uniform temperature actions for the structures analysis are defined using a simplified procedure abandoned by European and American design codes since the beginning of the 2000s. This situation has generated a gap in criteria for structural analysis, especially for bridges, due to the effects produced by temperature variation on structural elements, supports, joints and foundation elements. Impact on safety levels and pathological manifestations have been found in bridges due to the thermal actions of the environment, affecting maintenance and durability conditions. On the other hand, the occurrence of global warming has affected the climate and the ambient temperature, with a change in the extreme values and in the amplitude of temperatures. Through a literature review and an analysis of the behavior of some structures, the procedures recommended by the various existing standards and by recent research on the subject were analyzed, concluding that the current normative models use the extreme shade air temperatures as a reference to determine the actions employed in the designs, as well as maps for recording and consulting the values of these temperatures. The study concluded that the model recommended by Eurocode, the European design standard, with several recent applications, is suitable for the use of data from meteorological stations installed in Brazil, considering the period of data available, the stations location and the extension of the Brazilian territory. Within this context, the present research aimed to develop temperature maps for application in structural projects as a contribution to the future revision of NBR6118 Standard, attempting the criteria of NBR7187:2021 Standard. Thus, a methodological procedure was developed involving the processes of selection, treatment and analysis of data to obtain adjustment curves for determination, with a degree of confidence 90%, of the extreme values of maximum and minimum temperatures for the recurrence time of 100 years for each meteorological station, as well as for transferring the results and generating isocurves on georeferenced maps. Despite the continental dimensions of Brazil and the climatic variations found between the different regions, the conclusion is the application of the proposed procedure results in maps in which the interpolation of the dataset generates a continuous transition of values in the north-south direction, taking into account the estimated values, and the possibility of use by the designers of structures in a similar way to that used by the aforementioned international standards.