Testing and operation of Delaware's first permanently instrumented "smart" bridge

Harry W. ShentonAs many of the nation's bridges reach the end of their design service life, the reliability and safety of these bridges is becoming a major concern. Visual inspections conducted every two years are not thorough enough to fully assess the performance of a bridge. While other inspection methods are available, these processes require more time and many other resources. With this in mind the Federal Highway Administration (FHWA) initiated the Long-Term Bridge Performance Program (LTBPP), with its primary goal being to use permanently instrumented bridge monitoring systems throughout the country to gather quantitative data on the long-term performance and deterioration of our bridges. Bridge 1-821, located in Wilmington, DE, is a typical slab on girder steel design. Known as Delaware's first "Smart Bridge," it was instrumented with a structural monitoring system in 2006. The system consists of 61 sensors that include accelerometers, and displacement, temperature, and several types of strain gages. Sensor data is recorded by a Campbell Scientific CR9000X data acquisition system. Two main types of data are collected: monitor data and event data. Monitor data is taken every hour and is used to track bridge behavior from season to season and year to year. Event data is taken for 4 seconds when a predetermined threshold is reached for a trigger gage and is used to study the behavior of the bridge due to the site specific live load traffic, and to analyze the dynamic performance of the bridge. Recent work on the project included: (1) field work to repair strain gages and bridge completion modules that were malfunctioning, (2) developing software to implement a more reliable event trigger, and (3) developing MATLAB software programs to process and analyze collected data. Since this is a permanent monitoring project, monthly reports summarizing bridge behavior is a goal for the future. The current MATLAB programs are capable of accomplishing this task but additional work must be done to refine the process and increase automation, while decreasing human interaction and the time required for analysis.University of Delaware, Department of Civil and Environmental EngineeringM.C.E