SP_Constraint Commands
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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.

.. toctree::
   :maxdepth: 1

   sp_constraint/fix
   sp_constraint/fixX
   sp_constraint/fixY
   sp_constraint/fixZ

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