Models can be built from several type of finite elements.

All element types can be used for static, first order vibration or buckling analysis. Static and second oder vibration analysis with geometric nonlinearity is available only for beam structures.

FINITE ELEMENTS

Line elements: truss, beam, rib

Truss

Beam

Rib

The truss and the cubic beam element are the most widely used finite elements for bar, beam, or column modeling. The rib element is a 3-node isoparametric element with quadratic displacement interpolation that can be used similar to the beam element (but takes account for the shear deformations) or in conjunction with surface elements for eccentric rib modeling.

Surface elements: membrane, plate, shell

Quadrangular membrane, plate, shell

Triangular membrane, plate, shell

The surface elements are isoparametric flat quadrilateral (8/9-node) or triangular (6-node) elements. All use quadratic shape functions to interpolate displacements, and pass the patch test for arbitrary shape. The plate end shell elements use Mindlin's plate assumptions in a Heterosis formulation. 

Diaphragms
Using diaphragms means simplifying the model. Diaphragms are special rigid bodies where the relative position of the element nodes remain constant in a global plane.
It can be an advantage running vibration analysis of big models. Diaphragms can represent plates totally rigid in their planes.

The running time is reduced if the model contains only columns and slabs. If structural walls are included, the number of equations will be reduced but the band-width will be increased. The resultant running time may be greater than without diaphragms.

LINKS, GAPS, ETC.

Gap elements

Spring elements
The spring elements can account for linear or nonlinear elastic support or connection behavior.

Link elements

Edge hinges
Edge hinges can be defined between domain edges or between a rib and an edge. Both the edge and the domain have to be selected. Stiffness values must be defined in the local coordinate system of the edge.

Rigid elements
The rigid elements can model rigid parts of your structures without assigning large stiffness values to an element. The element can have any number of nodes.

SUPPORTS

Winkler-type elastic supports for line elements
These elements can model elastic foundation support conditions of line elements.
Nonlinear characteristics (tension only, compression only, or limit resistance)

Winkler-type elastic supports for surface elements
These elements can model elastic foundation support conditions of surface elements.
Nonlinear characteristics (tension only, compression only, or limit resistance)

Nodal supports with arbitrary orientation and stiffness
These support elements can have a specified stiffness, and the resulting internal forces are the support reactions.
Nonlinear characteristics (tension only, compression only, or limit resistance)