Service life prediction of bridges subjected to corrosion using time-dependent reliability method

Li, L 2018, Service life prediction of bridges subjected to corrosion using time-dependent reliability method, Doctor of Philosophy (PhD), Engineering, RMIT University.


Document type: Thesis
Collection: Theses

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Title Service life prediction of bridges subjected to corrosion using time-dependent reliability method
Author(s) Li, L
Year 2018
Abstract Bridges are key infrastructures that play an important role in transport systems, but the deterioration of this infrastructure has become a worldwide issue. This deterioration affects the capacity of a bridge structure and reduces its remaining life. It is, therefore, vital to study the corrosion effect on bridges and carry out service life prediction of bridges subjected to corrosion to avoid corrosion-induced failures and develop cost-efficient methods for the maintenance and rehabilitation of bridges.

The research aimed to develop a new method to predict the service life of a bridge subjected to corrosion. The first-passage probability theory was used to determine the time-dependent probability of bridge failure under different failure criterion and, subsequently, the service life of the bridge. To obtain accurate input information, simulated corrosion tests were conducted to determine the corrosion behaviour of steel with and without stress. Mechanical tests were undertaken to determine the degradation effect of corrosion on mechanical properties (yield strength, ultimate strength, failure strain and fatigue strength limitation) with and without stress. Hydrogen concentration measurement and microstructural analysis were conducted to determine the mechanism of corrosion-induced degradation of mechanical properties of steel with and without stress. Results of lab tests were correlated to natural corrosion through site inspection. Based on the results collected from corrosion tests and site inspection, bridge geometry and mechanical properties of bridge steel were modelled as time-dependent variables when carrying out time-dependent reliability analysis.

It was concluded that corrosion can lead to the reduction of ultimate strength and failure strain of steel. Corrosion can also cause delamination due to intrinsic differences in the microstructure across the thickness of steel plates. Additionally, the levels of reduction of mechanical properties and propagation of delamination are higher for stressed steel than for non-stressed steel at the same degree of corrosion. Also, due to the effect of corrosion, the stress range (S) magnitude for corroded steel is smaller than that for un-corroded steel at the same number of load cycles (N) to failure in the S-N curve. The research also indicated the degradation of mechanical properties is caused by corrosion- and hydrogen-induced changes in microstructural features. It was found, through reliability analysis, that fatigue failure is the most critical failure criterion and that not considering the effect of corrosion on mechanical properties leads to overestimation of the service life of bridges.
Degree Doctor of Philosophy (PhD)
Institution RMIT University
School, Department or Centre Engineering
Subjects Structural Engineering
Construction Materials
Civil Engineering not elsewhere classified
Keyword(s) corrosion
steel bridge
fatigue
mechanical properties
service life
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Created: Tue, 27 Nov 2018, 15:53:30 EST by Keely Chapman
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