Performance monitoring of a bridge superstructure using a dense, wireless sensor network

Performance monitoring of bridges is in great demand for existing and new Structures alike. A large number of today's bridges are rated as structurally deficient due to significant deterioration requiring investigation of their structural health. Discussed in this paper is the deployment of a dense wireless sensor system on a short span integral abutment bridge superstructure located in St. Lawrence County, New York. The Wireless Sensor Solution (WSS) developed at Clarkson University's Laboratory for Intelligent Infrastructure and Transportation Technologies (LIITT) is designed specifically for diagnostic bridge monitoring, providing independent conditioning for both accelerometers and strain transducers in addition to high-rate wireless data transmission and is capable of supporting large-scale sensor arrays. During the deployment, strain and acceleration Measurements are obtained simultaneously and in real-time at critical locations of the bridge under several loading conditions, including ambient environmental and traffic loading. Results from the strain data analysis aid to quantify the bridge static response, notably end fixity and load distribution along the girder length. Accelerometers provide the dynamic characteristics of the superstructure. An average normalized power spectrum is developed from acceleration measurements where the natural frequencies along with their corresponding mode shapes are extracted. The findings are compared to a developed analytical Finite Element Method (FEM) model based on the bridge as-built drawings. Results from the test deployment correlate well with the FEM model and the expected behavior for integral abutment bridge.