Constraint Commands
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.
fix fixX fixY fixZ
Non-homogeneous constraints are added with wither sp or imposedMotion commands inside the :ref:`plainPattern or multisupportExcitation commands.
MP_Constraint Commands
Multi point constraints (MP_Constraints) are constraints that allow the user to define the relationship between the response of a set of the degrees-of-freedom at one node (the constrained node) in relation to the response of the degrees-of-freedom at another node (the retained node). In structural analysis MP_Constraints are used to enforce rigid-diapgragm constraints or equal constraints (response of degrees-of-freedom at two nodes move the same)
equalDOF rigidDiaphragm rigidLink