INFLUENCE OF HEAVY TRUCKS ON HIGHWAY BRIDGES

In the present study, truck traffic data collected by the Florida Department of Transportation statistics office are grouped according to truck type and loading condition (loaded or empty). Mean values of truck axle weight and spacing are used to represent their average effects on bridge structures. The mathematical models of typical trucks with significant counts are established and the input data are derived from the synthesized results. These typical trucks include types 5, 8, 9, and 10. Road surface roughness is generated as multi-correlated random processes. According to the research by Honda et al., the coefficient of correlation is approximately taken as a constant. Static effects of the heavy trucks are compared with those of the standard design truck HS20-44. The tandem axle weights of the heavy trucks are found to be higher than that of HS20-44 and exceed the limit by the AASHTO Guide. Dynamic impact factors of moment at midspan and shear at end are analyzed for I-girder steel and prestressed concrete bridges ranging from 9.14 m (30 ft) to 42.67 m (140 ft). Effects of correlation of road surface roughness on dynamic impact factors are investigated. Fatigue accumulation damage incurred by the normal traffic at sites with significant counts is performed.