Structure Type

Open Structure Type dialog window, which selects a structure type to be created, using either method:

Click Geometry menu > Structure Type.
Click .

When opened, you can create one of the following: building, 2D truss, 3D truss, 2D frame, 3D frame, grillage, plate, shell, plane stress structure, plane deformation structure, axisymmetric structure, or a volumetric structure.

Robot can analyze the structure types in the following chart, which shows the coordinates and the nodal degrees of freedom that are defined when creating a structure. U denotes displacements in the X, Y, or Z direction in a global coordinate system, and R denotes rotations around the axes.

STRUCTURES	COORDINATES	NODAL DEGREES OF FREEDOM
2D frames	X, Y	UX , UY , - , - , - , RZ ,
2D trusses	X, Y	UX , UY , - , - , - , - ,
Grillages	X, Y	- , - , UZ , RX , RY , - ,
3D trusses	X, Y, Z	UX , UY , UZ , - , - , - ,
3D frames	X, Y, Z	UX , UY , UZ , RX , RY , RZ,
Plates	X, Y	- , - , UZ , RX , RY , - ,
Shells	X, Y, Z	UX , UY , UZ , RX , RY , RZ,
Plane stress structures		UX , UY , - , - , - , - ,
Plane deformation structures		UX , UY , - , - , - , - ,
Axisymmetric structures		UX , UY , - , - , - , - ,
Volumetric structures	X, Y, Z	UX , UY , UZ , - , - , - ,

Building is a structure template available in Robot. Building is not a structure type, but a template which facilitates defining this structure type. Available coordinates and nodal degrees of freedom for the building are identical as for shells.

Note: It is impossible to combine 3D bar models (the 3D frame type) with the following structure types: plate, plane deformation structure, or a plain stress structure.

Note: For 2 structure types (plane deformation structures and axisymmetric structures), the transversal dimension is always assumed to be 1 m, irrespective of the unit length specified in the Job Preferences dialog. This means that a structure sector of 1-meter thickness is modeled, which affects the interpretation of loads and reactions. For example, if the force unit [N] and the length unit [mm] are specified, then:

A linear load is treated as pressure with a value 1 [N/mm / m] = 1000 [N/mm2]
A concentrated load is treated as a linear load with a value 1 [N/m] instead of [N/mm].

A sum of reactions is interpreted analogously (always on the length of 1 m).

Note: For volumetric structures, you can define a 3D bar model (3D frame) or a shell structure. These element types that can be used in volumetric structures have 6 degrees of freedom: UX, UY, UZ, RX, RY, and RZ.