ABSTRACT
Super-heavy loading vehicles, also called superloads, have weight, size, and loading configurations different from those of traditional vehicle classes found in Federal Highway Administration (FHWA) classifications. In general, superloads include Implements of Husbandry (IoH), non-divisible vehicles, and other non-standardized industrial vehicles. Although oversize/overweight load permit regulations differ somewhat among State Highway Agencies, superloads can potentially exceed regulated load limits and cause unexpected distress and damage to pavement systems. Accordingly, to satisfactorily and more accurately determine the impact of superloads on pavement systems with less time-consuming pavement analysis, it is important to characterize superload loading configurations. This study will focus on a method of identifying the number of tire loadings (i.e., nucleus segment) required in analyzing the impact of IoHs on flexible pavement systems. Layered Elastic Theory (LET)-based analysis using MnLayer has been performed to determine the nucleus segments of IoHs, followed by determining critical flexible-pavement responses such as horizontal tensile strain at the bottom of an asphalt surface layer for assessing fatigue-cracking potential, and determining vertical compressive strain at the top of the subgrade for assessing rutting potential induced by applying a nucleus segment of IoH as a loading input. Using the superposition method, the critical flexible-pavement responses induced by the nucleus segments of IoHs can be compared to those induced by only one row of tire loadings within the nucleus segment to confirm its applicability to performing analysis of pavement under IoHs with reduced computational effort.
