Oancea, Marius-Adrian (1991) A comparative assessment of mechanistic load equivalence factors for flexible pavements. Masters thesis, Memorial University of Newfoundland.
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This study deals with mechanistic Load Equivalence Factors (LEF) for flexible pavements. It addresses two sets of objectives. First, a theoretical investigation of cycle counting methodologies used for mechanistic LEF's calculation was carried out. Second, a number of these methods were used for calculating LEF's from in-situ strains. -- The study includes an extensive literature review, starting with the empirical approach proposed by the AASHO Road Test (AASH0, 1961). Mechanistic methods for LEF's calculation are subsequently introduced and discussed. -- Next, the concept of fatigue cycle, as defined by the ASTM standard E 1049-85, is introduced and its applicability to flexible pavements is investigated. As a result of the comparison of all the fatigue cycle counting methods proposed by the standard, the Range-Pair Counting Method was selected for LEF's calculation. -- The experiment undertaken in order to obtain strain versus time histories included two experimental trucks, namely a 3-axle configuration and a 5-axle configuration. The experiment involved 3 levels of speed, 3 levels of loading and 2 replicate runs of the experimental vehicles for each speed and load combination. Each set of 2 replicate runs of the experimental trucks were followed by an equal speed run of the Benkelman Beam truck. -- Resulting strain versus time histories were evaluated in terms of the quality of the lateral placement. Those corresponding to the best lateral placements were processed by the proposed ASTM Range-Pair Cycle Counting method, by the mechanistic method employed during the RTAC 1986 study, and the results were compared to the empirical AASHO LEF's. A new integral approach, based on the cycle definition provided by the selected ASTM method for cycle counting, was also introduced. -- Comparative assessment of LEF's calculated by different methods was made in order to validate numerically and investigate the suitability of each method for LEF's calculation.
|Item Type:||Thesis (Masters)|
|Additional Information:||Bibliography: leaves 167-171.|
|Department(s):||Engineering and Applied Science, Faculty of|
|Library of Congress Subject Heading:||Pavements, Flexible--Testing|
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