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QuakeManager allows the user to easily and seamlessly compute, save, plot, search and select ground motions and their response spectra.
This discussion is mainly focused on ground motion response spectra (Sa, Sv, Sd, etc), although some discussion of FFT and PSD spectra is also included.
QuakeManager supports response spectra in multiple ways:
1.Automatic computation of response spectra. When a new ground motion is imported into the library and the user selects it, the response spectra are automatically computed.
2.Saving response spectra in the database for easy access and search. Once a response spectrum is computed, it is automatically saved in the database.
3.Automatic computation of resultant spectra (SRSS, Geomean, RotD100, etc)
4.Batch calculations of spectra for multiple records. In case of a large number of records, the user can choose to calculate or recalculate spectra (and intensity measures) of a given collection in one operation.
Read the following sub pages to learn more about Response Spectra and how QuakeManager calculates them:
•What is a Response Spectrum?
•Nonlinear Response Spectra
•Resultant (Biaxial) Response Spectra
•Rotated Spectra
•FFT, PSD & Other Spectra
Spectra Types
There are two types of response spectra: Component Spectra, and Resultant Spectra.
Component spectra are regular ground motion spectra values are different periods defined for each ground motion records (horizontal or vertical).
In contrast, resultant spectra are defined for Triplets, and are usually a measures of the bidirectional spectral intensity of the two horizontal components.
QuakeManager provides a multitude of ways to define resultant spectra. Having said that, the most common measures are usually SRSS, GM and RotD100.
The types of spectra currently defined in QuakeManager are listed below:
1.Component spectra (H1, H2 or V components)
2.Geomean: This is the geometric mean of H1 and H2 computed as Sqrt(Sa1 x Sa2) at each period T, where Sa1 and Sa2 are the component spectral values for H1 and H2 respectively, at period T.
3.Max(1,2): The maximum of H1 and H2
4.Min (1,2): The minimum of H1 and H2
5.SRSS: The SRSS of H1 and H2, equal to Sqrt(H12 + H22)
6.RotD100: Maximum Rotated Component. This is the maximum possible Sa value along all orientations between 0 and 360 degrees.
7.RotD50: Median Rotated Component.
8.RotD0: Minimum Rotated Component.
9.Comp 1: Component H1
10.Comp 2: Component H2
11.Comp 3: Vertical Component
12.FN Comp: Fault Normal Component
13.FP Comp: Fault Parallel Component
Of the above spectra, note that Component, Geomean, Max(1,2), Min(1,2) and SRSS are orientation-dependent spectra. This means that they depend on the initial orientation of the record. The remaining spectra are orientation-dependent, they are the same regardless of how the initial horizontal components are rotated (for example, whether they are rotated to as-recorded orientation or to Fault-Normal/Fault-Parallel orientation, or any other orientation).
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