The File > Export > Analytical Model command writes a CIMsteel Integration Standard (CIS/2 format) file that contains all the necessary analytical data to allow a third-party program to import the finite element representation. After being imported by the analytical program, the model is analyzed and designed to the appropriate section sizes, and then returned back to Smart 3D using the same file.
The CIS file contains all the necessary analytical data to allow third party programs to import the finite element representation of the analysis model. Generally, an analysis model is associated with a single CIS file. During the export process, nodes and finite elements are derived and written to the CIS files along with the boundary conditions, member releases, loads, and load cases and combinations. Because the nodes and finite elements only exist in the CIS file, the CIS file must be maintained throughout the life cycle of the analysis model.
If you need to update a third-party analysis model with changes made in the Smart 3D model after the initial analysis export from Smart 3D, you must use the same CIS file name for the update export. By using the same name, Smart 3D uses the existing file as input into the generation of the update export file. Smart 3D extracts the identity of the nodes and elements from the initial file and then uses this identification to create the new export file. If you do not use the same file name, Smart 3D creates new node and element identifications. Therefore, you will not be able to update the third-party analysis model because the node and element identifications will not match. For example, Model1A.stp was exported initially from Smart 3D. Now the Design Firm needs to send model changes to the Analysis Firm. The updated file to be exported must be named Model1A.stp. The original export file is renamed with a numbered prefix (based on the date) so the existing file is not over-written.