Vehicle-Induced Dynamic Performance of FRP versus Concrete Slab Bridge

In the United States alone, about 30% of the bridges are classified as structurally deficient or functionally obsolete. To alleviate this problem, a great deal of work is being conducted to develop versatile, fully composite bridge systems using fiberreinforced polymers (FRPs). To reduce the self-weight and also achieve the necessary stiffness, FRP bridge decks often employ hollow sandwich configurations, which may make the dynamic characteristics of FRP bridges significantly different from those of conventional concrete and steel bridges. Due to the geometric complexity of the FRP sandwich panels, dynamic analyses of FRP bridges are very overwhelming and rarely reported. The present study develops an analysis procedure for the vehicle-bridge interaction based on a three-dimensional vehicle-bridge coupled model. The vehicle is idealized as a combination of rigid bodies connected by a series of springs and dampers. A slab FRP bridge, the No-Name Creek Bridge in Kansas, is first modeled using the finite-element method to predict its modal characteristics, then the bridge and vehicle systems are integrated into a vehicle-bridge system based on the deformation compatibility. The bridge response is obtained in the time domain by using an iterative procedure employed at each time step, considering the deck surface roughness as a vertical excitation to the vehicle. The bridge dynamic response and the calculated impact factors are compared between the FRP slab bridge and a corresponding concrete slab bridge. Finally, the applicability of AASHTO impact factors to FRP bridges is discussed.