Health monitoring of precast bridge deck panels with glass fiber reinforced polymer bars

Glass fiber reinforced polymer (GFRP) bars are an innovative material that have special properties. One property is their noncorrosive nature that lends itself to being able to replace steel reinforcement in bridge decks; however, GFRP bars have a lower elastic modulus than steel reinforcement contributing to higher deflections unless a greater percentage of reinforcement is utilized. One way to monitor bridge deflections is to instrument the deck panels and check the various measurements. The bridge used in this research was constructed using precast GFRP reinforced deck panels and prestressed concrete girders. The deck panels were monitored throughout the transportation from the precast yard to the bridge by the use of electrical strain gauges. The bridge is instrumented with accelerometers that measure vertical accelerations of the girders, linear variable displacement transducers (LVDT) that measure vertical displacement of the deck panels and vibrating wire strain gauges (VWSG) that measure the strain in the concrete deck panels. Remote monitoring was done by the use of a secure modem. Data were collected for three purposes. First, lifting strains were measured, analyzed and compared to a finite element model. Collected data from electrical strain gauges were compared to tensile cracking limits. Second, long-term VWSG and LVDT data were recorded and charted to extract strains and deflections. Trucks with a known weight passed over the bridge while strains and displacement data were recorded during testing. Data were interpreted, iv analyzed and compared to design requirements. Third, multiple trucks with a known weight and speed passed over the bridge during testing while acceleration data was collected. Research was conducted to determine the impact factor for design, the period of the bridge, structural damping and primary mode shapes. This research showed that the lifting layout for large GFRP precast panels was successful for crack prevention during transportation and installation. This study recorded a performance history for future use of GFRP bridge decks showing that strain and deflections were well within code limits. Accelerometer data showed that the bridge is dynamically stable and that truck speed and axle weight are the main contributions to the acceleration response of the bridge.