Siren

Siren Benefits

  1. Units can be chosen from preset SI, kN-m, kip-ft of kip-in unit sets or specified individually for each component
  2. Data checking to identify invalid or inconsistent data
  3. Graphical output of time histories: displacements, velocities, accelerations, stresses and strains

About This Software

Easily model site response to seismic events

Siren is a site response analysis program that calculates the soil response, attributable to specified movement in the bedrock. This is achieved by modelling the soil as anon-linear one dimensional soil column with an earthquake motion input at its base.  Properties are assigned to the bedrock and the soil is modelled as a non-linear stress-strain curve which incorporates hysteresis effects.  Excitation is assumed to apply at the bedrock level and an explicit time integration scheme is used to calculate the soil response with time.

How does it work? Siren models the site as a column of soil overlying bedrock. The software assigns properties to the bedrock and the soil, which is modelled as a non-linear stress-strain curve incorporating hysteresis effects. The software assumes excitation applies at the bedrock level and uses an explicit time integration scheme to calculate the soil response with time.

Siren is the perfect addition to the toolkit of any engineer working on seismic design. 

Features:

  • COM Interface
  • Full technical support when maintained
  • Wizards to guide users in setting up the model
  • Units can be chosen from preset SI, kN-m, kip-ft of kip-in unit sets or specified individually for each component
  • Import of excitation time-histories in a variety of formats
  • Graphical representation of results
  • Data checking to identify invalid or inconsistent data
  • Multiple soil stress-strain curves and transmitting or non-transmitting boundaries
  • Control of integration time step and output time step
  • Graphical output of time histories: displacements, velocities, accelerations, stresses and strains
  • Graphical output of stress-strain histories
  • Calculation of response spectra
  • Export to Sigraph for post-processing

General Description

Within Siren, the movement of the soil is calculated by treating it as a one dimensional soil column.  The soil column is specified as a series of layers each with its own material properties, characterised by a stress-strain relationship and a bulk density. The program operates in the time domain enabling it to model non-linear soil properties with hysteretic damping.

For calculations of the soil response, the time over which the soil response is to be analysed is divided into a number of equal time steps, for which the soil response at each point can be calculated

Siren allows the following to be calculated for a specified soil column and bedrock movement:

  • Displacement, velocity and acceleration time response for any node
  • Stress-Strain curve for any element in the soil profile
  • Relative displacement at various elevations at any time
  • Base response spectrum and surface response spectrum
  • Spectral ratio (surface/bedrock)

This can in turn be used to assess the ground movement affecting a specific structure, or to review the peak ground acceleration to be considered during design.

Quick Overview

Siren is a site response analysis program that calculates the soil response, attributable to specified movement in the bedrock.

Features

  • Wizards to guide users in setting up the model
  • Units can be chosen from preset SI, kN-m, kip-ft of kip-in unit sets or specified individually for each component
  • Import of excitation time-histories in a variety of formats
  • Graphical representation of results
  • Data checking to identify invalid or inconsistent data

In Siren the site is modelled as a column of soil overlying bedrock. Properties are assigned to the bedrock and the soil which is modelled as a non-linear stress-strain curve which incorporates hysteresis effects. Excitation is assumed to apply at the bedrock level and an explicit time integration scheme is used to calculate the soil response with time.

  • Multiple soil stess-strain curves and transmitting or non-transmitting boundaries
  • Control of integration time step and output time step
  • Graphical output of time histories: displacements, velocities, accelerations, stresses and strains
  • Graphical output of stress-strain histories
  • Calculation of response spectra
  • Export to Sigraph for post-processing

Time Step Calculations

At each time step, the shear stress acting in each soil layer is calculated from the shear strain existing in that layer at that time. The net force on each lumped mass is calculated as the difference of the shear stress above and below the mass.

The acceleration is then calculated as the net force divided by the mass.  Having calculated the displacement of the masses, the shear strain and consequently the shear stress at the next time step, for each layer can be determined and the process is repeated until the total specified time is achieved.

 

Bedrock Excitation

  • You can input the physical properties and location of the bedrock. You can also specify bedrock level, density, shear wave velocity and whether the base boundary is considered as "transmitting"
  • You can model the partial transmission of waves into the rock underlying the soil deposit using the principal proposed by Papastamatiou (1973).
  • The excitation force is applied as a nodal force time history using a node specified by you.
  • You can specify the input excitation as a base motion or a force excitation.
  • You can apply a nodal force time history to the excitation force using a node you specify.

 

Viscous Damping

Viscous damping can be added into the system in addition to hysteretic damping. For normal situations this can be set to zero; however, they may be appropriate for modelling a simple structure on the soil surface.

 

Soil Materials

Allows input of the strain degradation curve for different soil types. The curve represents the degradation of shear modulus with increasing strain levels. A number of G/G0 curves have been proposed in various publications. By way of example these include for sands, the G/Go vs curves proposed by Seed et al. (1984) and for clays the relationships given by Sun et al. (1988).  The values of shear strain and the product of shear strain and shear modulus should be increasing. The shear stress and Damping ratio are calculated from the strain degradation curve by the program and cannot be edited by the user.

 

Soil Elements

Allows input of the location and material property number of each soil layer. Each soil element is located by its top level and assigned a soil material number, bulk density and yield factor. The data should be such that the natural frequency of each layer within the site is approximately equal (say 10 Hz). This can be achieved by assuming a natural frequency for a layer and then calculating its height.

 

Time History

This represents the expected bedrock motion for the site. This can be scaled to achieve the appropriate magnitude of motion. Scaling can be done by using the 'Wizard' button on the Tables toolbar.

Time histories should be selected from earthquake databases based on the magnitude, distance from recording station to epicentre, soil stiffness, significant duration, spectral shape close to the target spectrum, type of fault, etc.

 

Analysis Control

Allows specification of the method and location of the excitation motion, together with several analysis parameters.

For control of the time period analysed and reported in the results, specify the calculation time step (seconds) and the finish time (seconds). The number of time steps between output are used for the calculations between those whose results are stored for producing the detailed output.

Additionally, the excitation can be specified at bedrock level or as nodal force at any node, and a scaling factor can be applied to the acceleration time history.

Within this dialog you are able to specify time histories to be treated as X and Y pairs. This option does not affect the analysis, but can be used when exporting data to LS-Dyna. If checked, consecutive time history data sets will automatically be paired up to represent the X and Y planes, rather than specifying manually during the export process.

 

File Formats

Siren supports the 'srn' file type.  Data can be imported in other formats (GFD, TXT, CUR files).  There are options to save the data, both graphical and tabular, to other file formats.

  • You can export to Oasys Sigraph or to a siren text file.
  • You can export a table view to (txt, csv, html, cur).
  • Text can be exported to txt,csv,HTML & rtf formats

 

COM Interface

A COM interface has been included with Siren. This is a form of Application Programming Interface (API) that allows other programs to open Siren, and execute specific functions within the program.  This allows you to write scripts from other programs that will automate the use of Siren and extraction of results, potentially saving significant amounts of time on projects where a large number of analyses are required.

References

 

 

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Which type?

Standalone Licences
Locked to an individual machine but transferrable by the user to another machine.

Shared Licences (equivalent to Network)
Shared Licences can be activated on any number of machines, however you can only concurrently use the number of licences that you have purchased.

$455.00

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