Bridge Monitoring and Performance Evaluation

Abstract

Over fifty percent of our nation’s 560,000-plus bridges are obsolete or structurally deficient. To upgrade or replace these structures would require a serious budget. In order to shorten this list of bridges and to improve their ratings, state DOTs are investigating new repair techniques and better performance evaluation tools in order to implement the new drive to sustainability within the infrastructure. The research presented herein focused on the evaluation of current US bridge analysis and rating procedures for the North Carolina Department of Transportation (NCDOT). To evaluate these procedures, several bridges were rated with commercially available software and a newly developed spreadsheet program. In parallel, the bridges were also load tested for comparison, from which, it was concluded that the NCDOT’s bridge rating software directly follows the latest AASHTO requirements. The experimental results, however, also proved that the bridges had significant strength reserves associated to several factors, such as, girder/deck composite action, impact and distribution factors, material strength, and contribution of non-structural elements. In this research, a simplified bridge testing protocol was developed from which it was concluded, that a relatively simple instrumentation setup could be effective in the load rating of bridges through testing. The data gathered through these instruments provide vital performance data for normal traffic conditions, as well as during extreme loading conditions and evacuations, which could lead to less restrictive load ratings and removal of the structurally deficient classification, yielding a more sustainable structure.