Mechanistic calculation of load equivalency and truck factors for fatigue damage of hot mix asphalt using strain area method

Abstract EN

Among several pavement distress types, fatigue and rutting are the main distresses of flexible pavements.

to accurately assess the amount of damage that trucks with multiple axle groups cause to these flexible pavements, a summation methodology is imperative.

several methods have been used to sum the pavement damage due to multiple axle groups, researchers have used continuous methods, as well as discrete methods.

the continuous strain area method is a very good candidate for calculating the fatigue damage.

applying this method on the laboratory strain pulses proved superior to the discrete method.

the characteristics of the mechanistic strain pulse differs from the laboratory strain pulse, which indicates that the mechanistic strain area method for calculating the axle factors (AFS) needs to be calibrated with the laboratory-derived AF values.

the calibrated power was obtained by minimizing the sum of the square error (SSE) between both AFS that involved iteration over trial values.

this study employed two pavement cross sections, thin and thick, for analysis of the mechanistic strain area.

the load equivalency factors (LEFS) and truck factors (TFS) for multiple axle and truck configurations were calculated using the calibrated mechanistic strain area method.

the results showed that combining truck axles in a large axle group reduces the fatigue damage significantly (by about 50%) compared to the same number of individual axles.

moreover, wide-base tires impose more fatigue damage to the pavements than conventional dual tires bearing the same load and tire pressure.