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This article describes how SAP2000 creates input and analysis results files, and how users may archive those files.

Input files

The binary input .SDB file is the main SAP2000 input file. Additional input files may be created, depending on the load cases defined, to store specific information about the model. These separate input files are listed as follows:

  • Response-spectrum, time-history, power-spectral-density, and steady-state functions, defined through Define > Functions, may be stored in separate function input files when the From File function type is selected. Users have the option to convert the data stored in these external input files into user-defined sets in which function data is stored directly within the binary .SDB file.
  • Construction-scheduler data, created through Bridge > Construction Scheduler, is stored in separate input files with a .BCS extension .

Further, .SBK binary backup files and .$2K text backup files are automatically saved in the model directory. We recommend archiving the binary .SDB model file and the .$2K text backup file.

Analysis files

  • Binary analysis files are created during analysis to store intermediate and final analysis results. When the model is unlocked, these binary intermediate files are deleted, and analysis must be re-run to re-create these files.
  • To archive analysis results, the best approach is to export using Text, Excel, or Access format, the process for which is described in the next section.
  • The analysis log file with the .LOG extension contains useful information associated with completed analysis, such as numerical problems, convergence problems, total analysis time, etc.

Exporting results

  • Archived input files may be run to obtain analysis results.
  • Export and archive analysis results using Text, Excel, Access, or another common file format. Results may be exported through File > Export > SAP2000 .mdb, .xls, or .s2k.


Backup should account for all relevant input files and exported results. 

Some conditions in which archiving may be appropriate include:

  • When analysis results take a significant amount of time to generate. 
  • When results will be reviewed on a computer without  SAP2000
  • When results are archived for a particular software version. Then results from an upgraded version may be compared with those from the current version.


See also