RAM Concept allows you to specify six stiffness factors that modify the behavior of the slab elements (see description of the orthotropic behavior settings in Slab area properties and Beam properties ). When all of the factors are set to 1.0, the slab element behave as an isotropic material (a material having the same properties in all directions). When the factors are different from each other, the slab elements behave as an orthotropic material (a material having different properties along its three perpendicular axes.)

Care must be used when setting these stiffness factors. With certain combinations of factors, the structure can become unstable and the results can become unreliable. Also, the interaction of the stiffness factors may be more complex than it appears upon first inspection. This section gives some guidance to assist in avoiding these issues.