Reliability Analysis Of The Reinforced-concrete Bridges Considered Service Environment And Steel Corrosion Pattern

Corrosion of steel bars is the most important factor which causes failure of reinforced concrete bridges. The degradation caused by steel bar corrosion includes reduction of cross-sectional area, decrease of mechanical properties of steel and bonding between steel and concrete. These factors influence each other, and eventually lead to the structure failure. In this paper, in order to research deterioration of mechanical properties of steel bars, electrochemical acceleration method and mechanical simulation method are accepted to simulate pitting corrosion of steel bars. The time-dependent reliability of RC bridges under atmospheric environment and marine environment is analyzed based on test results and corresponding literature, with the decrease of strength and deterioration of bonding between steel bar and concrete considered. Research work in this paper could be introduced as:1. Two methods are used to research the mechanical properties of corroded steel bars:electrochemical acceleration method and mechanical simulation method. The corroding pit parameters such as depth, length, shape, number, spacing distance and location, are investigated to research the relationship between pitting corrosion and mechanical properties though mechanical simulation method. In order to simulate the rebar corrosion in real RC structure, electrochemical acceleration method is applied on 9 RC beams, and 52 corrosion rebar samples are tested in order to discuss the relationship between mechanical properties of steel bars, average corrosion rate, and minimum cross-sectional area. The investigation indicates that yield load and ultimate load of steel bars are mainly controlled by minimum cross-sectional area. Stress concentration caused by pits is not significant.2. According to test results and corresponding literature, three kinds of mechanical properties model, uniform corrosion model, pitting corrosion model and improved pitting corrosion model, are studied. Among the three models, the improved pitting corrosion model is proposed with steel corrosion pattern and the corrosion development procession considered. Thereby the rebar mechanical properties calculation is divided into two-stage.3. Resistance degradation model of RC bridge member under the atmospheric environment and the marine environment is proposed with degradation of rebar mechanical properties and bonding between concrete and rebar considered. Monte Carlo simulation method and the checking point method (JC method) are implied to analyze the time-dependent reliability of RC bridges.