Developing

Details about the internals of OpenSees.

Class Interface Specification  

Classes may be categorized as follows:

1. Domain: These classes describe the finite element model and store the results of an analysis on the model. The classes include Domain, Element, Node, Load, SP_Constraint, MP_Constraint, and their subclasses.

2. Analysis: These classes perform the analysis of the finite element model. The classes include the Analysis, ConstraintHandler, DOF_Numberer, SolutionAlgorithm, Integrator, FE_Element, DOF_Group and AnalysisModel classes, and their subclasses.

• Computational Classes: These classes allow for composing efficient computational strategies that take advantage of prolem features such as sparsity, symmetry, and parallelism. More specifically these include:

  • System of Equation These include the abstract SystemOfEquation and Solver classes, and subclasses of these classes. These classes are provided for the solving of large scale systems of linear and eigenvalue equations.

  • Graph These are classes used to provide information about nodal and elemental connectivity and sparsity of systems of equations. The classes include Graph, Vertex, GraphNumberer, GraphPartitioner, and their subclasses. There is no Edge class provided at present. In current design each Vertex stores in an ID the tag of all it’s adjacent Vertices. For graph numbering and partitioning this has proved sufficient.

  • Parallel Classes These facilitate the development of parallel object-oriented finite element programs, classes are provided for parallel programming. The classes in the framework support the aggregate programming model. The classes include Actor, Shadow, Message, MachineBroker, FEM_ObjectBroker, Channel, and their subclasses.

• Runtime Classes: These include the ModelNamespace and G3_Runtime classes. An analyst will interact with a ModelBuilder object, to create the Element, Node, Load and Constraint objects that define the model.

• Other/Utility Classes

  • Matrix Classes: These include the classes Matrix, Vector and ID (integer array). These classes are used in the framework for passing information between objects in a safe manner, and for small scale numerical calculations in element formulation.

  • Data Storage These are classes used to store data. There are two abstract classes TaggedObjectStorage and FE_Datastore. Objects of type TaggedObjectStorage are used as containers to store and provide access to the TaggedObjects in memory during program execution. FE_Datastore objects are used to store/retrieve information from databases, containers which can permanently hold program data.

  • Visualization Classes These are classes used to generate images of the model for the analyst. These classes include Renderer, ColorMap, and their subclasses.

This design allows for contributions in the fields of:

• Element and material modeling.

• Solution algorithms, integration procedures and constraint handling techniques.

• Model generation.

• Numerical analysis for solution of linear and eigenvalue problems.

• Graph theory for numbering and partitioning graphs.

• Data structures for container classes and database.

• Graphics.

• Message passing systems and load balancing in parallel environments.