Histograms of the gross vehicle weight (gvw) of trucks obtained from weigh-in-motion data for seven states are analyzed. These histograms are modeled by two bimodal distributions consisting of mixed pairs of lognormal distributions and a lognormal and a type iii largest extreme value distribution. Fatigue lifetimes for aashto categories a, b, c, and e details are calculated from these models of the distribution of gvw by approximating the miner's stress as a linear function of the mth root of the mth expected moment of the gvw. The lifetimes based on the two models are compared with each other and with the results obtained by assuming a single lognormal distribution. The results show that the lifetimes estimated using the bimodal distributions differ little from each other but are significantly shorter than the lifetimes estimated from the single lognormal distribution. It was also noted that there are large differences between the estimated lifetimes of different aashto categories. This paper appearsin transportation research record no. 1275, Bridge research 1990.
Abstract