Irregularities

For most of the horizontal and vertical structural irregularities defined in Tables 12.3-2 and 12.3-3, respectively, you must manually determine whether the structure is irregular for each force direction and indicate so in the Site Information dialog.

The program automatically detects horizontal Torsional Irregularities 1a and 1b and horizontal 4, Out of Plane Offset, and applies these to the determination of:

• the redundancy factor (12.3.4.2)
• application of 25% increase in drag strut forces (12.3.3.4).
• the application of accidental eccentricity in torsional analysis for rigid diaphragms

However these irregularities are not known before loads are generated, so they must be entered in the Site Dialog for their use for determining

• whether the structure is permitted for each Seismic Design Category (12.3.3.1)
• the regularity criterion for limiting the value of the design seismic response parameter S_DS (12.8.1.3).

If the program determination of irregularity is different than your initial appraisal, you can change the Site Dialog setting, regenerate loads, and redesign.

You can also override the program's determination of Torsional Irregularities 1a and 1b by settings in the Site Dialog.

The application of all other irregularities to these provisions depends solely on what you enter in the Site Dialog. The application of irregularities to the provisions is described in more detail in the subtopics to this topic.