Browsing by Author "Lim, Jason"
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Item Effects of Heavy Agricultural Vehicle Loading on Pavement Performance(2011-01) Lim, JasonAgricultural equipment manufacturers have been producing equipment with larger capacity to meet the demands of today’s agricultural industry. This rapid shift in equipment size has raised concerns within the pavement industry, as these heavy vehicles have potential to cause significant pavement damage. At present, all implements of husbandry are exempted from axle weight and gross vehicle weight restrictions in Minnesota. However, they must comply with the 500 lb per inch of tire width restriction which may lead to very large loads as long as the tires are sufficiently wide. A full scale accelerated pavement test was conducted at the MnROAD test facility. Both flexible and rigid pavements were tested in this study. This thesis presented analysis performed on the flexible pavement sections. The flexible pavement sections consisted of a “thin section” which represented a typical 7-ton road and a “thick section” which represented a 10-ton road. Both sections were instrumented with strain gages, earth pressure cells, and LVDTs to measure pavement responses generated by these heavy agricultural vehicles. These response measurements were compared to responses generated by a typical 5-axle semi truck. Additionally, tire contact area and contact stresses of these vehicles were measured. Through this research, it was determined that traffic wander, seasonal changes, time of testing, pavement structure, and gross vehicle weight have profound effects on pavement response measurements. The effect of vehicle speed and benefits of flotation tires over radial ply tires were not significant in this study. Additionally, all agricultural vehicles loaded above 80% of full capacity generated higher subgrade stresses compared to the 80-kip 5-axle semi truck. Layered elastic programs, BISAR and MnLayer were used in the modeling analysis. The contact areas of these vehicles were approximated through multi-circular area estimation. This detailed modeling of the contact area yielded a more realistic representation of the actual vehicle footprint. DAKOTA-MnLayer optimization framework was introduced to perform backcalculation analysis to determine Young’s moduli of the pavement layers. The backcalculated Young’s moduli resulted in a close match between predicted responses and field measurements.Item Effects of Implements of Husbandry (Farm Equipment) on Pavement Performance(Minnesota Department of Transportation Research Services Section, 2012-04) Lim, Jason; Azary, Andrea; Khazanovich, Lev; Wang, Shiyun; Kim, Sunghwan; Ceylan, Halil; Gopalakrishnan, KasthuriranganThe effects of farm equipment on the structural behavior of flexible and rigid pavements were investigated in this study. The project quantified the difference in pavement behavior caused by heavy farm equipment as compared to a typical 5-axle, 80 kip semi-truck. This research was conducted on full scale pavement test sections designed and constructed at the Minnesota Road Research facility (MnROAD). The testing was conducted in the spring and fall seasons to capture responses when the pavement is at its weakest state and when agricultural vehicles operate at a higher frequency, respectively. The flexible pavement sections were heavily instrumented with strain gauges and earth pressure cells to measure essential pavement responses under heavy agricultural vehicles, whereas the rigid pavement sections were instrumented with strain gauges and linear variable differential transducers (LVDTs). The full scale testing data collected in this study were used to validate and calibrate analytical models used to predict relative damage to pavements. The developed procedure uses various inputs (including axle weight, tire footprint, pavement structure, material characteristics, and climatic information) to determine the critical pavement responses (strains and deflections). An analysis was performed to determine the damage caused by various types of vehicles to the roadway when there is a need to move large amounts agricultural product.