General Settings

The General Settings tab is used to control the basic properties of the current project. The following sections are available

Project

Title
The title is included header of all output files.
Notes
The notes are only meant to help maintain one's sanity and are not used in any way.
Filename prefix
The filename prefix is prepended onto the standard filenames. Allowing for the filenames to be descriptive of the calculation.
Units
The units system changes the units of both the input and output between Metric and English. Changing the units system does not provide conversion between the two different systems.
Save motion data within the input file check box
When this check box is checked, the time-series data is included in the data file. This increases the size of the file, but allows for the file to be easily transfered.

Type of Analysis

Calculation Method
The calculation method switches between the time-domain and random vibration theory methods.
Vary the properties check box
Allows the user to vary the properties of the site.

Site Property Variation

Number of realizations
The number of sites profiles that are generated. For each site profile all of the motions are propagated through the site.
Vary the non-linear soil properties check box
Determines whether or not the non-linear soil properties (shear-modulus reduction and damping curves) are varied.
Vary the site profile
Determines whether or not the site profile (shear-wave velocity, layer thickness, and depth to bedrock) are varied.

Equivalent Linear Parameters

Strata performs equivalent-linear site response analysis which assumes linear-elastic wave propagation with strain compatible properities. The analysis is an iterative procedure which changes the properties in the layer such that properties use the previously computed effective strain for the layer.

Effective strain ratio
The effective strain ratio rates the maximum strain in the layer to the effective strain used for the equivalent non-linear soil properties. [Default value 0.65]
Error tolerance
The error tolerance is one of the exit conditions in the equivalent-linear site response loop. Once the error in both the damping and shear-modulus in all layers is below this level the iterative portion of the analysis stops. [Default value 1%]
Maximum number of iterations
The maximum number of iteration is the other exit conditions for the equivalent-linear site response loop. After reaching this number of iterations, the loop exits and a warning message is printed. [Default value 8]

Layer Discretization

Strata allows for variation of the layering thickness and shear-wave velocity therefore it divides the velocity layers into sub-layers for the wave propagation. The thickness of these sublayers is controlled by the maximum frequency and wavelength fraction. See technical manual for more information.

Maximum frequency
Maximum frequency of engineering interest. [Default value 20]
Wavelength fraction
The number of wavelengths contained within a sublayer. Typically ranges from 1/5 to 1/10, values less than 1/3 are not recommended. [Default value 0.2]