Determining Remaining Strength Capacity of Deteriorating RC Bridge Substructures

Condition-ratings in bridges have been used by the Federal Highway Administration as a way to classify structural deficiencies and structures that are functionally obsolete. These ratings are determined by evaluating the severity of the deterioration or nonconforming issues in affected bridges. The quality of the condition-rating practice is subjective (visual inspection based on the inspector’s view) and time delayed due to inspection cycles, which are scheduled for every two years. However, some deterioration may not be visible to the inspector. For instance, concrete substructures exposed to deicing salts or those in marine environments may begin experiencing deterioration or corrosion without showing any external damage. In addition, once a concrete substructure begins to experience these types of defects, the substructure’s durability becomes compromised. Consequently, it is important to evaluate damaged substructures and analyze the severity of the substructure’s degradation, the decrease in performance over time. This paper uses a risk-based approach (a nondestructive evaluation technique) to calculate and analyze some probabilities of failure associated with degradation factors. Overall, the objective of this research was to develop a generalized procedure, through the integration of deterministic and stochastic durability design methods, which analytically evaluates the durability of deteriorated reinforced concrete (RC) substructures. Furthermore, a decision tree is created to help inspectors exemplify the current condition or remaining strength of concrete substructures that have experienced degradation.