Análise comparativa em pilares de pontes: caso da ponte de Porto Nacional - TO

Abstract

The present work is a case study carried out in the city of Porto Nacional-TO, on the bridge over the Tocantins river located on the TO-255 that connects the city to the district of Pinheiropólis, being the access route to the municipalities of Fátima and Brejinho. from Nazareth. The main objective of this research was to carry out a special visual inspection, following the methodology of the Brazilian Standard (NBR) 9452:2016: Inspection of concrete bridges, viaducts and walkways - Procedure, to assess the state of conservation of the bridge's concrete pillars, since these are, according to the aforementioned standard, main elements, where the compromise of these structures can cause the collapse of the work. The inspection was carried out via vessel using a drone, the latter being an effective method for reaching pathologies that are difficult to access. During the inspection, photographic records were made, as well as visual identification and manual annotation, for later comparative analysis with the reports of the LSE (Laboratory of Structural Systems - São Paulo) 2017, in these reports the LSE carried out visual inspections throughout the structure of the bridge, identifying the damage present on the bridge. With the photographic collection in hand and the LSE reports, the analysis of the pathological manifestations in the bridge pillars was carried out. The inspected pillars were from P2 to P5, towards Porto Nacional – Pinheiropólis, and downstream and upstream faces, these being the right and left sides of the river, respectively. The results of previous research carried out by the LSE indicate that the pillars are the most damaged elements of the bridge, some of the problems identified were: corrosion of reinforcement, disaggregation and spalling of the concrete. Among the pathological manifestations most found in this work are infiltration, efflorescence, sludge and mainly the alkali-aggregate reaction (AAR), all of which rely on the presence of water

and its interaction with the concrete components in the structure. The alkali- aggregate reaction was found in the four pillars, and its presence was confirmed

through tests carried out by the LSE. The most damaged pillar is P4, according to academic works carried out by students from universities in the cities of Porto Nacional and Palmas, in addition to reports made by the LSE, with the reading of these it was possible to affirm the presence of intense cracking and RAA, concrete degradation and Armor exposure in inspected elements. When classified in the NBR 9452 standard, the result found was 1 for the four pillars, which means that they are in a critical condition, as expected, since this study is not the first to be carried out on the bridge, on the contrary, this is yet another work that corroborates the precarious condition of the structure. Finally, taking into account the work previously carried out on the bridge, the results obtained in this study and the literature, it is concluded that the lack of preventive maintenance reduces the useful life of Special Works of Art (OAE's) and in most cases it happens irreversible damage to the structure, as occurred with the Porto Nacional bridge, which will be replaced in the coming years.