Investigating bridge deck deterioration using failure analysis technique and Markov chains
Bridges in the United States and throughout the OECD countries are deteriorating at a very rapid rate. Bridges with reinforced concrete decks are no exception. Decks, more than any other component or subsystem in the bridge system has deteriorated the most requiring immediate repair, rehabilitation or replacement to maintain them at the desired level of serviceability which, at present require billions of dollars. Design inadequacy, bad construction practices, poor quality materials, nonuniform maintenance and repair, increase in traffic volumes and higher axle loads besides the influence of the environment, and the application of deicers are considered to be the factors contributing to deterioration of the deck. Deterioration is serious, and corrosion, scaling, spalling, leaching etc., are the very many indicators of deterioration.
A methodology consisting of a number of modules identifying the failure modes, effects, causes, failure mitigation and detection procedures, and a simple graphical method to identify the indicators of deterioration and quantify them based on extent, severity and significance for each defect, and then to relate the effect of each combination of extent, severity and significance to condition index range, with the ultimate objective to find the failure /reliability range is required, before undertaking a detailed condition evaluation and structural appraisal of the deck, to decide on the right type of maintenance, rehabilitation and or replacement decision. In this study an attempt is made to predict failure probabilities due to deterioration for reinforced concrete bridge decks and to find the associated service life range, so that this information can become useful in the much larger and comprehensive Bridge Management System designed solely for the maintenance and rehabilitation of the vast number of concrete bridges found in this country and elsewhere.