Finite Element Type

The result of the FE modelling process will consist of shell, beam and truss elements.

Shell elements are used to model thin structures where one dimension is much smaller than the other two dimensions. They decouple the deformation on the surface and the deformation in the normal direction, allowing for a simple and efficient simulation of a thin structure.

Beam or link (truss) elements are used to represent relatively long, thin pieces of structural continua where two dimensions are much smaller than the other dimension.

Beam elements assume the direct stresses in the nonaxial direction to be zero, and ignore the deformations in the nonaxial directions. For link elements, shear stress, stress gradients, and deformation are also ignored.

The final FE type may vary with the type of analysis. In a global model a girder is modelled as a beam, in a detailed model it might be necessary to consider the whole geometry and represent both web and flange as shell elements.

The user should be aware of element types and their structural capabilities. The element type selection also has enormous effect on size and calculation times in the later FEA.