ABSTRACT
The occurrence of structural accidents in Brazilian bridges, viaducts and pedestrian bridge in recent years has prompted the technical community to pay more attention to the state of conservation they are in. Due to its relevance, in 2016, the ABNT NBR 9452 standard was put into practice, which describes procedures to be taken in inspection of bridges, viaducts and concrete pedestrian bridges. Many of these constructions are over 50 years of construction (reference service life in Brazil) and have had little maintenance over the years, both its structural components as well as constructive elements, which have a specific design life for which periodic maintenance should be considered. In the great majority, the structures of Brazilian bridges are executed in reinforced and prestressed concrete. Therefore, they must comply with the durability requirements of ABNT NBR 6118: 2014. The conception given by this standard involves environmental conditions and exposure time, cover thickness, types of cement, compressive strength and water/cement ratio. It is evidenced that the approach given to the classes of environmental aggressiveness is linked to the pathological manifestations due to attacks by chlorides. Structures of bridges located in the marine environment, especially in tidal areas, are subject to a greater probability of degradation, especially the corrosion of the reinforcement bars due to the chloride ions attack. From an economic point of view, corrective measures taken in the design phase are less expensive, and it is necessary to adopt considerations of durability in the structural design so that the engineering work has a good safety and longevity performance. The present work constitutes an exploratory numerical analysis of methodologies likely to be applied in the design phase of bridges so that the structure of reinforced or prestressed concrete is built within specifications that allow to reach a pre-established service life. Four commercial software were used to obtain the necessary cover thickness to avoid the corrosion of the reinforcement against the attack by chloride ions and a comparative analysis of the results obtained with those specified by ABNT norms.
