Post-Processing

The opstool framework adopts xarray as its core data structure, leveraging its powerful capabilities for handling labeled multi-dimensional data. This choice provides a flexible and intuitive way to manage and process structural analysis results.

You can learn xarray through the following resources:

Xarray in 45 minutes

Project Pythia

In a nutshell

In opstool, saving responses is very simple. You only need to run the analysis iteratively and use the following concise code:

>>> ODB = opst.post.CreateODB(odb_tag=1, **kargs)
>>> for i in range(Nsteps):  # you need to run the analysis iteratively
>>>    # perform analysis for one step
>>>    ops.analyze(1)  # or other analysis commands
>>>    ODB.fetch_response_step()  # fetch response at this step
>>>    # if you want to fetch response every 10 steps
>>>    #  if i % 10 == 0:
>>>    #     ODB.fetch_response_step()
>>> ODB.save_response()  # save the responses after the analysis is done

opstool.post.CreateODB is used to create a database object, where odb_tag specifies the label. Then, the method opstool.post.CreateODB.fetch_response_step() is called to iteratively save the data at each step. Once the analysis is complete, all responses are saved by the method opstool.post.CreateODB.save_response(). That’s it.

The above code will automatically retrieve and save most of the commonly used output quantities of OpenSees.

Other args in kargs can be used to customize the output, such as specifying which response types to save, the frequency of saving, computing derived stress measures, and project Gaussian points responses to nodes, and more.

Note

  • odb_tag is used to label different datasets (different sets of responses). Subsequent post-processing and visualization will rely on this odb_tag for data retrieval.

  • The analysis must be performed iteratively (e.g., using a loop) to enable the step-by-step fetching of responses.

  • Static and dynamic analyses are both performed step-by-step, so the post-processing is consistent.

Supported response types

The following is a non-exhaustive list of response types supported by opstool:

  • “disp”

  • “vel”

  • “accel”

  • “reaction”

  • “reactionIncInertia”

  • “rayleighForces”

  • “pressure”

  • “localForces”

  • “basicForces”

  • “basicDeformations”

  • “plasticDeformation”

  • “sectionForces”

  • “sectionDeformations”

  • “sectionLocs”

  • “axialForce”

  • “axialDefo”

  • “Stress”

  • “Strain”

  • “basicDeformation”

  • “basicForce”

  • “Stresses”

  • “Strains”

  • “secForce”

  • “secDefo”

  • “sectionForces”

  • “sectionDeformations”

  • “Stresses”

  • “Strains”

  • “sectionForcesAtNodes”

  • “sectionDeformationsAtNodes”

  • “StressesAtNodes”

  • “StrainsAtNodes”

  • “Stresses”

  • “Strains”

  • “StressesAtNodes”

  • “StressAtNodesErr”

  • “StrainsAtNodes”

  • “StrainsAtNodesErr”

  • “StressMeasures”

  • “StrainMeasures”

  • “StressMeasuresAtNodes”

  • “StrainMeasuresAtNodes”

  • “Stresses”

  • “Strains”

  • “StressesAtNodes”

  • “StressAtNodesErr”

  • “StrainsAtNodes”

  • “StrainsAtNodesErr”

  • “StressMeasures”

  • “StrainMeasures”

  • “StressMeasuresAtNodes”

  • “StrainMeasuresAtNodes”

  • “globalForces”

  • “localForces”

  • “localDisp”

  • “slips”

  • “disp”

  • “vel”

  • “accel”

  • “pressure”

  • “lambdas”