ABSTRACT
Maryland Transportation Authority (MDTA) plans to upgrade their overpass bridges with link slab connections since joint failures are common problems of bridge deterioration in the United States. In the link slab connection pilot study, bearings under the steel girders are modified to allow both rotational and longitudinal movements, thus minimizing the negative moments transferred between spans and the forces imparted to the connection. This paper proposed and performed a retrofitted bridge condition assessment method using wireless sensors. In order to evaluate the performance and detect any occurring cracks of ductile link slab material (UHPC and ECC), wireless accelerometers, strain gauges, and displacement sensors are installed on site during the field test and structural health monitoring. In this study, strain gauges are improved by attaching them on thin aluminum plates and then installed before concrete pouring. By calibrating with several types of modified strain gauges which directly attached to the concrete surface in the lab tests, strains measured by the proposed embedded strain gauges attached to aluminum plates could closely represent the true strains. In addition, with these tests and experiments, finite element analyses of the pilot bridge have also been conducted. These results are critical for calibrating measured data from the field test and monitoring. Finally, the real-time/dynamic performance of the link slab system and the entire bridge would be evaluated, and recommendations would be provided.
