Durabilidade das estruturas de concreto armado: estudo comparativo entre prescrições normativas acerca de controle de fissuração

Abstract

The excessive crack widths in reinforced concrete structures compromise their essential functions, such as support capacity and protection against aggressive agents. Thus, the regulations for durability usually have concerns with the cracking behavior in concrete. In Brazil, the durability of reinforced concrete normalization has some inconsistencies, related to design parameters, such as the exposure classes and the crack width models. In this sense, this work has as the main objective to behave a critical analysis between ABNT NBR 6.118, Eurocode 2, and fib Model Code 2010, regarding the durability requirements for reinforced concrete structures, such as exposure classes, concrete quality and steel, cover thickness, serviceability and crack width. Parallelly, it has made analyzes to the influence of these parameters in the crack width estimate and in the serviceability from concrete, as well as were showed guidelines to be incorporated in Brazilian design processes, in order to obtain a better performance of the structures. To this end, were made qualitative and quantitative analyses of the normative precepts. The first one was responsible for highlighting the differences present in the analyzed parameters, and the second one was responsible for the study of a bi-supported beam, subjected to the variety of requirements that interfere in the estimation of crack opening. Differences were found between the national standard and the international standards studied; however, it is clear that the standard has prescriptions that fit the limits of durability, being as strict as the international codes. Finally, it is observed that this work helps in the study of the properties of reinforced concrete and the requirements related to the durability of structures, showing the influence of differences found in the standards that estimate the durability of reinforced concrete structures.