In this study, the bearing capacity of strip footing located on fiber reinforced soils has been defined using the stress characteristics method. The composite of soil and fibers has been considered as a homogeneous but anisotropic soil, as well as fiber orientation distribution has been considered in both isotropic and anisotropic conditions. Earthquake effects have been considered as horizontal and vertical pseudo-static coefficients.
First the stress equilibrium equations along characteristics have been obtained and then these equations have been analaysed with finite difference method. A computer program has been prepared to defining the bearing capacity. This is able to evaluate the stress characteristics net, distribution of ultimate bearing capacity beneath the footing and stress information at different points of the net, respect to soil and reinforcing parameters. The ultimate bearing capacity is calculated by averaging the distributed traction beneath foundation. Using this program and run it in frequent times, as well as considering different values of parameters, the graphs and charts have been obtained for practical and designing purposes in static and dynamic conditions, moreover the bearing capacity and rupture zones obtained in different conditions have been compared respect to different friction angles and reinforcing parameters. It is shown that use of fiber in soils, increases the bearing capacity of soils and also the bearing capacity increases while the content of fibers closer to horizontal orientation increases.