Parham Hayati - Assistant Professor, Faculty Member of Islamic Azad University Science and Research Branch, Tehran, Iran,
Niloufar Salehipour Bavarsad - MS.c. in Road and Transportation Engineering,

Pavement materials in terms of the mechanical and under the environmental conditions,operational and storage, have different behaviors. In this paper, flexible pavement models were designed and compared for damage and economic factors based on pavement lifetime in Kenlayer software using variables such as materials with linear and nonlinear elastic behavior in fine-grained/ granular type and: continuous interface (A)/discontinuous ; asphalt/base (B); subbase /subgrade (C); base/subbase/subgrade (D). Models: 1- nonlinear base; 2- nonlinear subbase; 3- nonlinear subgrade; 4- combination 1 - 2; 5- combination 2 - 3 (viscoelastic behavior of asphalt and linear rest ). Research results revealed that depending on type, behavior, and interface of layers, the pavement damage factor, which affects pavement lifetime, varies between ratio of damage with horizontal tensile strain bottom the asphalt layer and vertical compressive strain top soil subgrade. In 15-25 years lifetime range, models 1, 2, 3, and 5 best, and models 1, 2, 4 (fine-grained ) with 5 to 7 years, offered worst design. Groups C, D in models 1 (granular) and 2 , 3 (fine-grained) increased lifetime 3 to 70 years, models 2 and 3 (granular) reduced lifetime 2 to 13 years. B resulted in severe damage. According to the results of damage ratio, a index for the assessment of models based on the Lifetime Calculated, is predicted. in the simulated models, A index (DRετ/DRεc), showed a vast and different range

Flexible Pavement; Materiale Type and Behavior; interface of layers;Kenlayer software; A index (DRετ/DRεc)