Thermal behaviors of concrete and steel bridges after slab replacements with GFRP honeycomb sandwich panels

Abstract

During the last several decades, fiber-reinforced polymer (FRP) panels have been applied as one of the alternatives for slab retrofits and replacements in bridge engineering. Even though with many benefits, e.g., high strength, light weight, long-term durability, and good corrosion resistance, the FRP structures have not been widely adopted. It is partly due to the lack of national design guidelines and the uncertainties on long-term performances. Many studies have been conducted to investigate the static and dynamic performances of FRP bridges, while the studies on their thermal responses are not adequate. Therefore, the present study demonstrates an investigation on the thermal behavior of a FRP bridge based on a slab replacement project conducted by the Kansas State Department of Transportation, i.e., a steel deck replaced by glass FRP (GFRP) panels. The temperatures of the bridge and ambient air are recorded from December 2002 to July 2004. Firstly, a finite element model is developed using a sub-structuring method. This method is particularly efficient for modeling structures with complex configurations and subjected to the traffic and temperature loadings. Then, the model is verified by comparing the predicted live load distribution factors with that of a live load test; and it is further adopted to study the thermal responses using the measured temperatures from January 24 to July 13 in 2004. Finally, a parametric study is performed to study two general slab replacement cases, i.e., bridges with concrete beams and steel girders, respectively. Different loading conditions are considered, including the uniform temperature variations, temperature gradients, self-weights, and HS-20 live loads. Results from this study indicate that careful attentions should be paid to the thermal responses of bridges. The temperature gradients and uniform variations evidently affect the performance of bridges after replacing the concrete slabs with GFRP panels, such as the induced vertical deflections, horizontal movements, and stresses of steel girders or concrete beams.