Parameters of a structure seismic analysis depend on a seismic code used during calculations of a structure influenced by seismic impact. Select French seismic code AFPS ("Recommendations Association Francaise du Genie Paraseismiques 90") or PS 92 ("Regles Parasismiques Francaise 1992") in the New Case Definition dialog or click Parameters in the Analysis Type dialog.
To complete the seismic analysis according to the rules given in the code, define the following parameters:
- Zone - The Seismic zone number
- Parameters:
- Topography and/or behavior factor
- Structure Type
- Structure Site (if the Envelope option is selected, the Parameters button becomes accessible; its pressing opens the Spectrum Envelope dialog box)
- Spectrum Type:
- Design
- Elastic
-
Direction
- Horizontal
- Vertical
In the lower part of the dialog, the Direction definition,Filters and Residual mode buttons are located.
Click Eccentricity Definition to open the Definition of mass eccentricities dialog where you can specify how to account for the eccentricity of a mass in the seismic analysis.
The seismic excitation multiplier is calculated as follows.
Sa = aN * τ * ρ * R
where:
aN - acceleration depending on the zone number and the structure type,
τ - topographic coefficient depending on the tangent of the inclination angle,
ρ - damping correction coefficient depending on the damping ratio,
R - value of spectrum calculated by Robot, depending on the structure type, site type and risk type.
The details concerning this structure analysis method can be found in the mentioned code.