3.1. Model Commands

These are the commands added to the interpreter to create the finite element model. A finite element model consists of Nodes, Elements, Constraints, and Loads. In OpenSees the Constraints are divided into two types: single-point constraints (SP_Constraints) for specifying the boundary condition for a specific degree-of-freedom at a node and multiple-point constraints (MP_Constraints) for specifying the relationship between the responses between the degrees-of-freedom at two separate nodes. The loads in OpenSees are assigned to LoadPatterns. Also associated with load patterns are TimeSeries objects ans sometime SP_Constraints when the user wants to specify time-varying SP_Constraints.

Fig. 3.1.1 OpenSees Model

In OpenSees there are commands to add each of these types of objects to a domain:

• 3.1.1. model Command
• 3.1.2. node Command
• 3.1.3. SP_Constraint Commands
• 3.1.4. MP_Constraint Commands
• 3.1.5. uniaxialMaterial Command
• 3.1.6. nDMaterial Command
• 3.1.7. section Command
• 3.1.8. Geometric Transformation Command
• 3.1.9. Element Command
• 3.1.10. Time Series Command
• 3.1.11. Pattern Command
• 3.1.12. Damping Commands