鉄筋腐食の空間変動性を考慮したRC部材の構造性能評価

早大学位記番号:新7806早稲田大

Investigation of the Spatial Variability of Steel Weight Loss and Corrosion Cracking: A Novel X-ray Technique

The performance of corrosion-affected RC members depends strongly on localized damages of reinforcement. Therefore, modeling the spatial variability of steel corrosion is very important for the assessment of the remaining service life of corroded structures or time for maintenance. To study the changes of spatial variability of steel weight loss over time, a continuous monitoring is necessary. In this paper, a novel procedure of X-ray technique application in monitoring the spatial growth of a corroded bar in a RC specimen is demonstrated along with the digital image processing of X-ray images to estimate the steel weight loss. The relationship of steel weight loss and corrosion cracking is studied at different stages of corrosion. The validity of the estimation method of steel weight loss is also presented. In this study, a novel procedure of X-ray technique application in monitoring the spatial growth of corroded bars in RC specimens is demonstrated along with the digital image processing of X-ray images to estimate the steel weight loss. A single RC beam (80 mm × 140 mm × 1460 mm) reinforced with a longitudinal rebar and stirrups were fabricated for the investigation. The steel corrosion was accelerated via an electrochemical test. The relationship of steel weight loss and corrosion cracking was studied at different stages of corrosion. The validity of the method was also discussed. The outcome of spatial variability of steel weight loss might be used to validate analytical models for estimating non-uniform steel corrosion or incorporated with inspected corrosion levels of in-situ structures for the input data in a predicting model to estimate the long-term structural performance of corroded RC structures

Modeling spatial variability of steel corrosion using Gumbel distribution

Performance of corrosion-affected RC structures depends on the spatial variability of steel corrosion of reinforcing bars. The effect of spatial variability of steel corrosion on the remaining service life of concrete structures is significant. In this paper, an experimental study was conducted to investigate the effect of current density on the spatial variability of steel corrosion. This variability is modeled using Gumbel distribution derived from experiments and incorporated with FE method to estimate the yield loading capacity of RC beams. The results show that using Gumbel distribution parameters derived from the specimens with high current density may lead to an overestimation of load capacity of corroded RC beams.This work was supported by Waseda University Grant for Special Research Projects (project number: 2018B-146)