Page Comparison

This pages describes what files are created by SAP2000 during model creation and analysis, and what files should be saved for archiving.

h1. Input Files

For SAP2000, the main input file is the *.SDB file* which is the binary input file. Depending on the load cases defined in the model, the program sometimes uses additional separate input files listed below to store special information about the model:

* Response Spectrum, Time History, Power Spectral Density and Steady State functions (all defined via "Define > Functions") are sometimes stored in *separate function input files* when the "From File" function type is chosen. The user however has the option to convert the data stored in these external input file into a "user defined" data in which case the function data are stored directly within the binary .SDB file.
* Construction scheduler data (please note that construction schedules can be created via the "Bridge > Construction Scheduler" menu command) are stored in separate input file with *.BCS* extension.

The program also automatically saves *.SBK binary backup files* and *.S$K text backup files* in the model directory. It is recommended to archive the .S2K text backup file in addition to the binary .SDB model file.


h1. Analysis Files

During the analysis the program creates a number of *binary analysis files* that are used to store intermediate and final analysis results, such as displacements, forces, time history analysis results, etc. If you unlock the model, all these binary intermediate files will get deleted and you would need to re-run the model to re-create these files. If you need to archive the analysis results, the best approach is to export them using Text, Excel, or Access format as described in the next section.

Analysis log file with .LOG extension contains useful information (such as numerical problems, convergence problems, total analysis time, etc.) about the completed analyses.

h1. Exporting Results

Although archiving only the input files will enable you to obtain results by re-running the model, it may be also good idea to export and *archive the analysis results using some common file format, such as Text, Excel spreadsheet, or Access database*. Analysis results can be exported using the "File > Export > SAP2000 .mdb, .xls, or .s2k" menu command and by selecting all analysis results tables. Below are some common situations when archiving analysis results using this approach should be considered:

* Re-running the model to obtain analysis results takes significant time.
* You need to review the results on a computer without SAP2000.
* You need to archive results for a particular version of the program. If you upgrade to a higher version of the program, this will enable you to compare the current version results from the previous version results, if needed.


h1. Summary

{info}
Ideal backup strategy should involve backing up all relevant input files and backing up all exported results that are desired for convenient accessibility.
{info}

h1. See Also

* [Backups and troubleshooting corrupted models]
* [Import FAQ]
* [kb:File format]

{related-incident:no=23763|comment=Output file for archiving.}

{related-incident:no=24973|comment=Archiving SAP2000 models.}