Time-dependent deterioration of FRP bridge deck under freeze/thaw conditions

A FRP bridge deck is composed of several constituent materials with different characteristics. Under weathering conditions, individual constituents can degrade at different rates. As described in this paper, a mechanics model has been formulated to simulate the changes in load capacity and structural stiffness of FRP decks over time. A key element in these simulations is to include the quantitative effect of sustained loads and environmental exposures on the deterioration rates of the strength and stiffness of the constituent materials. Such data can be generated from accelerated laboratory testing and input as constitutive laws in finite element analyses for the deck design. The results indicate that the reductions in strength and stiffness of the glass/vinyl ester composites are substantial after 10,000 h freeze/thaw cycles only when the composites were also subjected to a sustain load of 25% strain, whereas the reductions are insignificant when the composites were not preloaded. For a thin wall sandwich structure deck, local buckling failure is most likely the dominant cause of the deck failure.