During spring thaw, restrictions on allowable axle weights (load limits) are often applied to flexible pavement sections in seasonal frost areas to prevent premature failure of thaw-weakened pavements. Currently, load limits are selected on the basis of experience. An approach to load limits that is based on controlling seasonal rates of fatigue consumption is described. Fatigue consumption can be determined from fatigue curves that relate critical tensile strains in the pavement section to the number of load repetitions causing fatigue failure. By using a layered-elastic computer program, strain is determined for the traffic loads applied to the pavement while it is in various seasonal states. Seasonal values for elastic-response parameters (resilient modulus and Poisson's ratio) are determined in laboratory tests on appropriately conditioned specimens. By relating the fatigue damage produced to the number and magnitude of loads applied during each of the seasonal pavement conditions, the effects of alternative load limit policies on remaining pavement life can be compared. In an application of the method to an existing pavement it was decided that the maximum axle load permitted during the spring-thaw period should be one that produced the same rate of fatigue consumption as the normal-summer-fall legal maximum of 18.9 kips. Using this criterion, the maximum spring-thaw load for the pavement would be 11.5 kips. Comparisons indicated that the remaining service life under the posted 14-kip load limit would be 80 percent of the life remaining if the 11.5-kip load limit were imposed. If no special spring-thaw period load limit is imposed, the remaining service life of the pavement will be reduced to 40 percent of the life remaining under the 11.5-kip limitation. (Author)

Media Info

  • Media Type: Print
  • Features: Figures; References; Tables;
  • Pagination: pp 22-30
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00381783
  • Record Type: Publication
  • ISBN: 030903561
  • Files: TRIS, TRB
  • Created Date: Mar 30 1984 12:00AM