algorithmic modeling for Rhino
How to set infinite stiffness for the beam element in Karamba 3d?
at the moment (Karamba3D 1.3.1) it is not possible to have infinitely stiff beams. You can make them very stiff though by e.g. defining a material with a high value for Young's Modulus.
The problem is, that if a model contains elements with hugely different stiffnesses the associated stiffness matrix which forms the basis for calculating the nodal displacements gets ill-conditioned. This means that the accuracy of the solution deteriorates.