When the "Run Analysis" button is pressed, the "Spectral Analysis Results" dialog is called, and the analysis starts. Two progress bars at the bottom of the dialog show the analysis progress. The lower progress bar shows progress of the whole analysis, while the upper one shows the progress of the current series.

For example, if spectral results are desired for a combination of 40 periods and 5 strengths, the lower progress bar can be imagined to start at 0 and progress uniformly to 200, while the upper one would go from 1 to 5 repeatedly, once for each period until all the periods are done, that is 40 times.

When a spectral analysis is performed, a large number of spectral quantities are computed and made available for plotting or data export. See the Spectral Quantities section for a description of all available Spectral Quantities. Of those quantities, any two quantities can be plotted against each other on the X and Y axes of the plot (see Figure 10).

Linear Spectra

Bispec can construct linear spectra for a ground motion or a suite of ground motions. The user specifies the mass, the damping ratio, and the period range. The periods or frequencies to be used can be specified by the user as a range by specifying the minimum value, maximum value and number of periods. The user has control on how the values are generated as they can be evenly (linearly) spaced, or Logarithmically spaced, if it's desired to have more points at small periods/frequencies. For linear spectra, the user may specify a range of damping values by entering multiple values separated by commas in the damping box.

Nonlinear Spectra

For nonlinear analysis, Bispec allows the specification of two parametric variables: Period/Frequency and Strength/Ductility/Damage Index allowing "Constant Strength", "Constant Ductility", or "Constant Damage" spectral computations. Note that ranges of strength and ductility are specified similarly to periods and frequencies, with the ability to specify linear or log spacing. In addition, custom ranges can also be specified by typing multiple values separated by commas.

The selection of two parameters for nonlinear spectra (period and strength/ductility/damage) results in a "matrix" of values for each of the result quantities. This is shown graphically on the plot by using different series to represent one of the parameters (either period/Frequency or strength/ductility) being constant. The data can be plotted as either "Equal Period", "Equal Strength", "Equal R" or "Equal Ductility". See Figure 10 in which the various series represent "Equal R" lines.

For the bidirectional case, spectral values can also be plotted for each direction, as well as for the 2D resultant.

The two directions and the resultant spectral values can all be shown simultaneously if the data consists of only one series (constant strength spectra with one strength for example).

Results can be plotted both in 2D and 3D.