What types of coordinate systems are in SCIA Engineer?

Different types of co-ordinate systems are used in SCIA Engineer.
These are important for the modeling of the structure and the definition of loads and supports, and of course also for the interpretation of the results.

Remark: The axes have fixed colors, namely X axis = red, Y axis = green, Z axis = blue.



The GCS is the co-ordinate system which is visible and activated when creating a new project. The GCS origin and the directions of its axes are fixed and cannot be modified.
The directions of these axes are shown at any time at the bottom left corner of the model space.

Figure 1: Global co-ordinate system.



The UCS is a co-ordinate system defined by the user, and overwrites the GCS. (The GCS can in fact be seen as a special case of the UCS.)
A UCS can be created and adapted via the ‘UCS’ icon in the ‘Tools’ toolbar:

Figure 2: UCS icon.

At any moment it’s possible to re-activate the GCS, also via this icon.

All co-ordinates entered via the Command line, relate to the UCS activated at that moment.
The properties menu of a node always shows its co-ordinates with regard to the GCS and with regard to the active UCS:

Figure 3: The Properties menu of a node.



Each structural entity (e.g. 1D member, 2D member, node) in SCIA Engineer has its own local co-ordinate system.

For 1D members the x axis of the LCS always coincides with the length axis of the beam, and is positive in the direction from beginning to end node.

Figure 4: Local co-ordinate system.

The orientation of the x axis can be reversed by swapping beginning and end node, e.g. via the ‘Reverse orientation’ icon in the ‘Geometry manipulations’ toolbar:

Figure 5: Geometry manipulations toolbar.

The local y and z directions can be adapted if desired, by means of a ‘LCS rotation’ via the Properties menu of the 1D member:

Figure 6: LCS rotation.

For 2D members the z axis of the LCS is always perpendicular to the element plane.

Figure 7: LCS co-ordinate system of 2D member.

The sense of the z axis can be inverted by selecting the option ‘Swap orientation’ in the Properties menu of the 2D member. Also an ‘LCS angle’ can be entered to define a rotation of the local x and y axes around the local z axis:

Figure 8: Properties menu of 2D member.

Furthermore a distinction has to be made between the LCS of a 2D member, and the LCS of an element of the finite element mesh.
Each mesh element also has its own local co-ordinate system. Also here the z axis is always perpendicular to the element plane. For the mesh elements of a curved 2D member, we can find for instance the following result:

Figure 9: LCS of the finite element mesh.