RigidElement

RigidElement is an MpcElement, with virtually infinite stiffness. Nodes contained in a RigidElement have no relative displacement regarding eachother. Best usecase is rigid diaphragm in structures. Some other use cases of rigid element can be found at: https://mashayekhi.iut.ac.ir/sites/mashayekhi.iut.ac.ir/files//files_course/lesson_16.pdf

This does represents a nondeformable element or element with infinite stiffness which does not deform. For more info see http://www.codeproject.com/Articles/850733/RigidElements-in-BriefFiniteElement-NET

ref[1]: http://www.edwilson.org/book-wilson/07-cons~1.doc

TODO: an appropriated image