General Commands

• Sensitivity_Command_Manual
  • General Commands
    • reliability
    • parameter
    • addToParameter
    • updateParameter
    • sensitivityIntegrator
    • sensitivityAlgorithm
    • recorder
  • Material Commands
    • uniaxialMaterial
    • nDmaterial
  • Section Commands
    • Fiber
    • Elastic
    • Aggregator
  • Element Commands
    • dispBeamColumnWithSensitivity
    • quadWithSensitivity
    • bbarBrickWithSensitivity
  • Constraint Commands
    • Transformation

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reliability Command

This command creates the reliability domain in which the sensitivity, reliability and optimization components are kept. This

reliability domain is parallel to the finite element (FE) domain in OpenSees. Currently, the commands for stand-alone sensitivity :analysis (e.g., sensitivityIntegrator, sensitivityAlgorithm) are set in the reliability domain only and, thus, the ‘reliability’

reliability

parameter Command

In DDM-based FE response sensitivity analysis, the sensitivity parameters can be material,

geometry or discrete loading parameters. Each parameter should be defined as:

parameter $tag <specific object arguments>

addToParameter Command

In case that more objects (e.g., element, section) are mapped to an existing parameter, the following command can be used to

relate these additional objects to the specific parameter:

addToParameter $tag <specific object arguments>

updateParameter Command

Once the parameters in FE model are defined, their value can be updated:

updateParameter $tag $newValue

sensitivityIntegrator Command

For static analysis, the only option currently available is the following, which must be defined before the ‘analysis’ command.

sensitivityIntegrator -static

For the dynamic case, currently only the Newmark algorithm is available. Two command need to be used together:

integrator NewmarkWithSensitivity $gamma $beta

sensitivityIntegrator -definedAbove

Currently, ‘-definedAbove’ is the only option available in OpenSees. This means that the same integration scheme (i.e.,

‘NewmarkWithSensitivity’) is used to perform both response and response sensitivity analysis.

sensitivityAlgorithm Command

The most general command is the following, which computes the response sensitivity at each time/load step, after the response

has converged.

sensitivityAlgorithm -computeAtEachStep

In those cases in which the sensitivity computation does not need to be performed at each step (e.g., for linear elastic systems : subjected to static pushover analysis), the sensitivity computation may be performed only at the time/load steps required by

user:

sensitivityAlgorithm -computeByCommand

However, before using the ‘-computeByCommand’ option, it is the user’s responsibility to make sure that the response

sensitivities computation is not needed at each time/load step. For example, in case of incremental nonlinear FE analysis or

dynamic analysis, using the ‘-computeByCommand’ option will produce wrong sensitivity results.

recorder Command

To record the nodal response and response sensitivity, the most commonly used format is:

recorder Node -file disp29.out -time -node 29 -dof 1 <–precision 16 > disp

recorder Node -file ddm29G1.out -time -node 29 -dof 1 "sensitivity 1"

recorder Node -file ddm29G1.out -time -node 29 -dof 1 "velSensitivity 1"

recorder Node -file ddm29G1.out -time -node 29 -dof 1 "accSensitivity 1"

The above ‘recorder’ commands (extended for recording response sensitivities) save into files (with the file name defined after : the command ‘-file’) the responses and response sensitivities of the node 29 along the first degree of freedom (dof) direction. : Response quantities can be ‘disp’ (displacements), ‘vel’ (velocities) and ‘acc’ (accelerations). Response sensitivities are

denoted by a string in double quotes and containing the response quantity identifier (i.e., “sensitivity” for displacements,

“velSensitivity” for velocities and “accSensitivity” for accelerations) and the sensitivity parameter specified by the parameter : tag ( in this example the tag is 1).

The command ‘-precision’ is optional, and allows users to change the number of digits used to record into file the response

and/or response sensitivities. This command is particularly useful when the finite difference method is used to verify/validate : DDM-based FE response sensitivities, since high accuracy in the results may be needed.

The user may also get responses and response sensitivities directly using the following Tcl commands:

nodeDisp 29 1

nodeVel 29 1

nodeAccel 29 1

sensNodeDisp 29 1 2

sensNodeVel 29 1 2

sensNodeAccel 29 1 2

These commands return the responses of the node 29 along the first dof, and their response sensitivities with respect to the

parameter with tag 2