How to eliminate tension from a subsoil?
When modelling 2D members it is possible to define a surface elastic foundation – subsoils – as a support for these elements. However, these subsoils have by default tension capabilities which means it might occur the subsoil gets under tension. Negative contact stresses indicate tension in the subsoil.
Since this behaviour is not realistic, it is necessary to eliminate these values. This can be done by performing a nonlinear calculation for which the functionality ‘Support nonlinearity/basic soil spring’ is needed. This functionality can be activated within the functionalities tab ‘Nonlinearity’.
In order to perform a nonlinear calculation, it is necessary to create one or multiple nonlinear calculations. These combinations can be defined within the service ‘Load cases, Combinations’. When generating the results for the nonlinear calculation, the tension in the subsoil will be eliminated and the contact stresses will have a positive value which represents pressure.