Análise da confiabilidade dependente do tempo de vigas de concreto armado afetadas pela corrosão por carbonatação

Abstract

In this work, an approach is presented to evaluate the reliability index over time for a reinforced concrete beam subjected to climatic conditions that promote the corrosion process of reinforcement due to carbonation. The proposed evaluation method combines a mathematical model capable of predicting the advance of the carbonation front in the piece as a function of its exposure time to various climatic factors, along with analytical models for determining the load- bearing capacity of corroded beams and Monte Carlo simulation (MCS) techniques. The random events generated using MCS allowed for the creation of various scenarios related to the structural element's characteristics, such as loading rates (permanent and variable) and strength, as well as environmental conditions related to the structure's location. The generation of samples of variables related to the environment (temperature and humidity) was made possible through statistical analysis of the climatic parameters recorded by meteorological stations in the region, enabling the definition of the data distribution type, mean, and deviation. The effect of the beam cover thickness on the variation of the reliability index of the beam over time was evaluated. The results indicate that beams with reinforcement ratios between 0.15 and 0.50% tend to maintain the reliability index value above the minimum normative values required for 50 years. Furthermore, through the analysis of the carbonation front, it was observed that the advancement of the corrosion process due to carbonation is more aggressive in the first 30 years of the structure's lifespan.