As of version 2025.b, it is now possible to enter "Ibarra-Medina-Krawinkler" type plastic hinges in CYPE 3D. This hinge allows users to model a behaviour of strength and stiffness reduction after yielding by means of a Backbone type curve.
The "Plastic hinges" option in the "Bar" menu defines the plastic hinges' relative position and their properties, as well as the degrees of freedom of rotation on which they act. Up to version 2025.b, "Elastic-linear Hardening" plastic hinges could be defined. From now on, the new "Modified Ibarra-Medina-Krawinkler" type can also be selected.
The data required to define the behaviour of a plastic hinge for a given degree of freedom of rotation are shown in the following image.
In the entry panel for the "Ibarra-Medina-Krawinkler" plastic hinge, there is an aid for visualising the behaviour curve and a legend of the symbols used in the curve.
In the stress display, plastic hinges that have reached the yielding point in the selected combination will be highlighted with an increase in size and a colour change.
