Requesting a Help for PLAXIS 2D modelling

Question

Hi. Can someone explain me why we should not model the length direction of a strip foundation when settlement analysis?

Faseel Khan · Answer

If the length in the out-of-plane direction is quite large compared to the width of the foundation (roughly greater than10 times), then plane strain conditions exist. In 2D, we model the strain conditions as plane strain conditions which means no normal and shear strains in the out-of-plane direction. The 2D analytical solutions for strip foundations consider plane strain conditions and so the 2D finite element model should match the analytical solution when plane strain conditions exist. If, on the other hand, the length in the out-of-plane of direction was not large and say was only 2 or 3 times the width of the foundation then plane strain conditions would not exist and therefore a 3D model would be used instead. The saying that you should not model the length direction of a strip foundation is rather to simplify modelling to avoid extra computation time. A 2D model is easy to construct and analyze compared to a 3D model. The 2D section of a strip foundation represents the major part and the most critical part of the strip foundation and the conditions at this section exist for almost the whole strip foundation and therefore only one 2D section is analyzed for such foundations.