Laserfiche WebLink
<br />Feb.08 05 09:24a <br /> <br />Cit~ of F~lcon Heights <br /> <br />6516448675 <br /> <br />, <br /> <br />. <br /> <br />PAVEMENT AND ENVIRONMENTAL FACTORS <br /> <br />. <br /> <br />Over the range of pavement designs typical of primary and secondary roads, fatigue <br />damage wries by a factor of 20. The primary pavement and environmental factorS affecting <br />damage are: <br /> <br />. Roughness in the road surface excites truck dynamic axle loads which increases <br />fatigue damage. Rough pavements (2.5 PSI) experience damage at a rate that is <br />approximately 50% greater than that of smooth roads (above 4 PSI) for most typical <br />truck suspensions. With a walking-beam tandem suspension, however, rough roads <br />may experience damage as much as 3 times greater than that of smooth roads. <br />Roughness does not systematically affect rutting damage of flexible pav=ntS. <br /> <br />. Elevated temperatures increases permanent deformation of the pavement layers in <br />flexible pavements. Over the temperature range from 770 to 1200F, the rutting <br />damage from this mechanism increases by a factor of 16. <br /> <br />. The temperature gradient in a rigid pavement slab is most important to fatigue <br />damage, because of the thermal stress created. With a gradient of one degree <br />Fahrenheit per inch in the slab, the fatigue damage from most truCks increases by a <br />factor of 10 over that of a zero..gradient condition. <br /> <br />In the process of conducting this study, sholtcomings and deficiencies in the <br />knowledge affecting our ability to predict truCk-road interactions have been identified. The <br />pavement models for flexible pavements need general improvement, along with the <br />methods for predicting damage. Rigid pavement models need more development for <br />analysis of damage accrual at cracks and joints, and methodology for studying damage <br />needs to be modified to inveStigate damage under stress conditions that include tensile and <br />compressive loading. Broad sholtcomings in the knowledge of trucks are apparent More <br />empirical information on the dynamic properties of trucks and truck suspensions is needed, <br />along with more infonnation on truck tire properties. <br /> <br />. <br /> <br />xi <br /> <br />p.5 <br />