Deterioration modeling and rehabilitation decision analysis for assessing the performance of bridge deck expansion joints

Bridge deck expansion joints play an important role in the functioning of bridge structures. They provide room for bridge decks to expand and provide seals to prevent water and debris from penetrating the bridge substructure. When they fail to function properly, the performance of bridges can be seriously affected. In the past two decades a great deal of research has been conducted to evaluate the performance of different types of joints. Some of these prior research projects were based on field evaluation, while others utilized in-house laboratory tests. However, a systematic approach is lacking to explore the relationship between the joint condition and the factors that could affect the joint performance. The condition rating of bridge joints is discrete and ordinal and has three levels, i.e., good, fair, and poor, and this research presents a methodology that uses the ordered regression model to predict the joint condition. The joint types investigated in the research are: compression seal (B.S.), strip seal (S.S.), and integral abutment (I.A.). The source data is from the 1998 bridge inspection records provided by the Indiana Department of Transportation (INDOT). The estimation result confirmed the findings of the previous field studies as to different parameters\u27 influence on the joint condition. The research also showed how joint deterioration curves can be developed and used to compare the performance of different types of joints. The dynamic programming approach was then used to provide a rehabilitation decision support system for determining the best time to repair and replace a joint within the life cycle of a bridge deck. With the objective of minimizing the total cost, this approach suggests the best rehabilitation policy of the joint for each possible length of the service life of the bridge deck. A sensitivity analysis was also conducted to determine the influence of the interest rate and the related cost values on the rehabilitation policy. This research focused specifically on three types of expansion joints, but the methodologies can be applied to other infrastructure systems as well. The models presented in this research are expected to provide an easy and effective way to evaluate their performance