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A. To check for soft stories and seismic code irregularities

To check for soft stories and other seismic code irregularities in rigid diaphragm structures, use the following procedure.

Note: Soft story checks and plan irregularities are applicable to structures with rigid floor diaphragm definitions. Refer to M. To assign nodes to a floor diaphragm.
The CHECK SOFT STORY option may added to a FLOOR DIAPHRAGM command set to check for soft stories per either IS 1893 2002, IS 1893 2016, or ASCE 7-05 codes. The CHECK IRREGULARITIES command may be added to check plan irregularities for the IS 1893 2016 or ASCE 7-05/10/16 codes.
Tip: You can check plan and vertical irregularities and structure stiffness per EC8 using the Earthquake workflow.
  1. On the Analysis and Design ribbon tab, select the Miscellaneous Commands > Floor Diaphragm Options tool in the Analysis Data group. The Floor Diaphragm Options dialog opens.
  2. Select the building code for which you want to perform earthquake checks:

    IS1893 2002

    or

    IS1893 2016

    or

    ASCE7-05/10/16

  3. Check the option Check Soft Story to perform this check.
  4. (IS 1893 - 2016 or ASCE 7 only) To check for plan and other vertical irregularities, check the option Check Irregularities.

    For IS 1893 2016, the program can check horizontal irregularities (torsional and reentrant corners) per Table 5 and vertical irregularities (mass irregularities and irregular modes of oscillation) per Table 6.

    For ASCE 7-05/10/16, the program can check horizontal irregularities (torsional and reentrant corners) and vertical irregularies (mass). Irregular modes of oscillation are not considered for this code.

  5. (Optional) If the base of the structure is not the minimum global Y coordinate defined in the structure, then check the Base Level option and then type the height of the structure base in the adjacent field.
  6. Click Add.
Note: Additionally, the story stiffnesses used in calculating story drift or checking soft stories can be added to STAAD.Pro output by including the command PRINT STORY STIFFNESS in the post analysis print commands section.
Parent topic: Analysis
Related reference