3.1.2. Model Class

The Model class is an alternative to the model command in Python that creates an isolated model that is safe from global state corruption. An instance of Model has all of the standard OpenSees modeling commands exposed as methods.

class Model(ndm, ndf=None, echo=None)

Create an isolated model for given number of dimensions and number of DOFs.

ndm integer	number of dimensions (1,2, or 3)
ndf integer	number of dofs (optional, default ndm*(ndm+1)/2)
echo FileLike	Optional file handle to write command history to.

Note

The Model class is currently only available in the experimental opensees Python package, but may eventually be added to openseespy. To install opensees, just run:

pip install opensees

This experimental package exposes an identical interface to openseespy, but must be imported as opensees.openseespy as opposed to openseespy.opensees. For more information, visit GitHub.

The Model class prevents inadvertent corruption of global state that may be caused when using the model command of OpenSeesPy. Each instance of a Model owns a unique instance of an interpreter which can only be manipulated through the instance itself. This interpreter can be be used from Python to invoke either Tcl or Python commands to create Nodes, Masses, Materials, Sections, Elements, LoadPatterns, TimeSeries, Transformations, Blocks and Constraints. These additional commands are described in the subsequent sections.

3.1.2.1. Example

The following examples demonstrate the creation of a Basic model builder that will create nodes with an ndm of 2 and with 3 degrees-of-freedom at each node.

import opensees.openseespy as ops
model = ops.Model(ndm=2, ndf=3)

model.node(1, 2.0, 3.0)
...

Note that opensees must come before openseespy in the import statement.

For more examples, visit the STAIRlab example [gallery](https://stairlab.github.io/opensees-gallery).

Code Developed by: cmp