Longitudinal joints are thought to provide relief from expansion and contraction of the bridge deck owing to temperature change, shrinkage, and live loads, especially for a wide bridge. Historically, however, these joints have been known to leak, allowing chloride-laden water to reach the bottom of the deck overhang and even the exterior girders. Research conducted by Phares et al. indicated that the development of cracking in bridge decks seems less dependent on the total width of the deck and more so on internal restraint of the abutment to temperature changes and, in particular, gradients. Based on the finite element method (FEM) results, an effective solution to reduce cracking in the deck might be to place an isolation pad between the soil and the back side of the abutment. The primary objective of this paper is to investigate the effectiveness of an isolation foam block at the back of an integral abutment in reducing the stress-induced strain and the deck end longitudinal and diagonal cracking near the end of the deck with an integral abutment. To achieve this objective, a highway bridge (Viking Road Bridge) in Iowa, US, designed with a width of 228 ft, was selected for the study. The bridge deck has no longitudinal joints but, based on the previous research results, it was equipped with thermal isolation pads behind the abutment. The newly constructed bridge was monitored for over two years, and this was followed by multiple bridge inspections. An analytical study was conducted to investigate the efficiency of the isolation foam on the bridge deck end structural behavior. The results indicated that the thermal isolation foam is effective in reducing the temperature gradient through the abutment thickness, especially on extremely cold days. By reducing the temperature difference between the abutment and the deck, a thermal isolation block is effective at reducing the deck end strain and resisting deck end cracking. The FEM results indicated that the maximum deck stress-induced strain was 46% greater without the effects of the thermal isolation block and greater than the concrete cracking strain. This indicated that, without the thermal isolation pad, the Viking Road Bridge could crack at the end of its deck.

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Bridges are continuously exposed to environmental changes and dynamic loading effects caused by moving loads. As a result, bridge deterioration is a critical problem in the U.S.A. The National Bridge Inventory (NBI) database contains historical bridge condition information for bridges in the U.S.A. and currently it is the best available database for describing the historical condition of bridges in the U.S.A. The objective of this paper is to develop a mathematical model that can be used to predict the future condition ratings of each bridge component and, more specifically, to estimate the probability of each bridge component being at any condition rating at any future year. Two different types of future condition rating prediction models, namely the current practice model (CPM) and the deterioration prediction model (DPM), were developed. The CPM is capable of simulating the effects of historical maintenance activities when predicting the future condition rating probabilities, whereas the DPM does not consider the effects of historical maintenance activities when predicting the future condition rating probabilities. Both models were illustrated and validated using most current NBI data. The performance of both models was evaluated on hundreds of bridges in the states of Iowa and Wisconsin. The results indicated that the CPMs tend to converge to condition rating 6 within 15 years, whereas the DPMs tend to converge to condition rating 4 with 15 years. This suggests that conducting current maintenance activities helps to keep the nation’s bridges in at least “satisfactory condition.” However, a lack of performing any maintenance could lead to bridges being structurally deficient within 15 years.