The axle load shifts of four truck types during braking are estimated using theoretical braking models and the implications of these axle load shifts for bridge and pavement design are explored. The truck types examined are a three-axle straight truck, a five-axle tractor semi-trailer, a seven-axle tractor semi-trailer with two air-lift belly axles, and a seven-axle B-train tractor-double trailer, each loaded to legal Ontario limits with weigh-out commodities. Each of the truck types experienced a substantial load transfer to the front steering axles under braking, mainly from the rear tandem axle groups, where the front axle load increase varied from 38 to 48%. The bridge design implications of the load shifts are examined in terms of the Ontario Bridge Formula. The pavement damage implications are analyzed in terms of load equivalency functions. It is suggested that the major damage implications are at intersections in urban areas and that increased structural sections could be designed to handle the increased equivalencies.
ASJC Scopus subject areas
- Civil and Structural Engineering
- Environmental Science(all)