3.1.3. SP_Constraint Commands

Single point constraints (SP_Constraints) are constraints that define the response of a single degree-of-freedom at a node. These constraints can be homogeneous (=0.0) or non-homogeneos. Non homogeneous SP_Constraints, which define the non-zero response of the degree-of-freedom, can be constant or time varying. In the OpenSees interpreters there are a number of commands to add a homogeneous SP_Constraint.

• 3.1.3.1. fix Command
• 3.1.3.2. fixX Command
• 3.1.3.3. fixY Command
• 3.1.3.4. fixY Command

Non-homogeneous constraints are added with wither sp_constraint/sp or imposedMotion commands inside the :ref:`plainPattern or Multisupport Excitation commands.