Seismic Analysis Parameters (Canadian Code NBC 2015)

The parameters of a structure seismic analysis depend on a seismic code used during the calculations of a structure influenced by seismic loads.

Select Canadian seismic code NBC 2015 in the New Case Definition dialog or click Parameters in the Analysis Type dialog.

To access the dialog:

1. Click Tools Job Preferences Design Codes.
2. In the Loads section select NBC of Canada 2015 from the seismic loads menu.
3. Click Analysis Analysis Types.

   The Analysis Types dialog opens.

4. Click New. The New Case Definition dialog opens.
5. Select Seismic, choose NBC of Canada 2015 and click OK.

   The Parameters dialog opens.

Code parameters

The code parameters for a seismic analysis according to NBC 2015 are defined as follows:

• Site classifications for ground (A, B, C, D, E, F) conform with Table 4.1.8.4.-A
• Site classifications for ground (A, B, C, D, E, F) conform with Table 4.1.8.4.-A.
• Factors Sa(T) where Sa(T) - 5% damped spectral response acceleration, for periods T of 0.2 s, 0.5 s, 1.0 s, 2.0 s, 5.0 s and 10.0 s, depend on the selected province, and conform with Table C-3.
• F(T) - site coefficient for spectral acceleration, for periods T of 0.2 s, 0.5 s, 1.0 s, 2.0 s, 5.0 s and 10.0 s, as defined in Sentence 4.1.8.4.(5).

  Manual definition of F(T) parameters is optional for site classes A-E after checking the box for 'User defined F(T) values' and obligatory for site class F.

• Factor PGA - Peak Ground Acceleration, as defined in Sentence 4.1.8.4.(1).
• Factor PGAref - reference PGA for determining F(T), F(PGA) and F(PGV), as defined in Sentence 4.1.8.4.(4).
• Site coefficients Fa and Fv for a selected site class, according to subsection 4.1.8.4 (7) (and Table 4.1.8.4.-B and Table 4.1.8.4.-D).

  The displayed factor values depend on the selected province and site. You can change these values manually or you can click Region to change the province and site of reference.

• Coefficients:
  • IE (earthquake importance factor) conforms with table 4.1.8.5.
  • Rd (ductility-related force modification factor) and Ro (overstrength-related force modification factor) factors conform with Table 4.1.8.9.

In this dialog, you can also access and modify the Direction definition, Filters, and Base Shear by clicking the dedicated buttons.

You can find the details concerning this structure analysis method in the mentioned code.