A fast and stateless interface to the OpenSees framework for finite element analysis.

This is an experimental package that provides an optimized OpenSees Tcl interpreter, as well as a new set of Python bindings that is both idiomatic, and free of global state.

The package may be used as a drop-in replacement for both OpenSees.exe and OpenSeesPy (see Getting Started below), and generally provides a substantial performance boost. Project objectives include:

• Performance The opensees package uses the experimental OpenSeesRT analysis kernel which eliminates reliance on global variables for state and memory management. New template classes in matrix/ allow for stack-allocated matrices and vectors and eliminate the need for static local variables which is leveraged to furnish substantial performance improvements. Switching Python scripts to use opensees typically results in a 4x to 5x performance boost.

• Reliability The core OpenSees runtime has been redesigned so that all program state is encapsulated in user-instantiated classes, and global variables/singletons are avoided. This eliminates several preexisting vulnerabilities to inadvertent state corruption.

• Semantics ...

Additional features include:

• Convert OpenSeesPy scripts into equivalent Tcl files that can be used for faster processing or serialization. Unlike most conversion utilities, this conversion is done exactly and does not rely on hand-rolled parsing.

• The package can be installed with pip for Python versions 3.7 - 3.12 on Linux, MacOS and Windows, but eigenvalue analysis is currently broken on Windows.

This package is experimental and not yet intended for public use.

• To start a Tcl interpreter run the shell command:

  python -m opensees

• The opensees package exposes a compatibility layer that exactly reproduces the original OpenSeesPy functions, but does so without mandating a single global program state. To run OpenSeesPy scripts, just change the import:

  import openseespy.opensees

  to

  import opensees.openseespy

  For true stateless modeling, the Model class should be used instead of the legacy model function; documentation is under development.

See also:

• osmg OpenSees Model Generator
• sees Modern rendering library
• mdof Optimized system identification library
• sdof Optimized integration for single degree of freedom systems

For more projects by the STAIRlab, visit https://github.com/STAIRlab .