Volume 40, Issue 6 (November 2012)
Fatigue Crack Assessment of Asphalt Concrete Pavement on a Single Span Highway Bridge Subjected to a Moving Truck
Characterization of fatigue crack in asphalt concrete (AC) pavement placed on the bridge is quite complex because it involves not only viscoelastic behavior of AC mixture but also dynamic interaction between bridge and traffic. In this study, a new approach that accounts for these material and structural aspects of the problem has been proposed to evaluate the fatigue crack potential of AC pavement on the bridge. A highway bridge surfaced with the 13-mm stone mastic asphalt (SMA) pavement that was subjected to a moving two-axle dump truck was selected as a simulation target and its equation of motion was derived using the Lagrange’s formulation. Given the range of testing variables, the maximum center deflections of the bridge were calculated and converted into the peak strains at the bottom of the SMA pavement. A simplified linear viscoelastic continuum damage model (S-VECD) was then implemented for the strains ranging from the largest peak strain to the specified allowable strain to predict the fatigue life of the SMA. The outputs showed that the fatigue life of the SMA got shorter as strain increases, and that hard SMA failed earlier than soft SMA. It was also found that SMA’s temperature was more influential than vehicle’s speed in causing fatigue cracks.