The analysis of the deformation capacity is subject to the condition that the model geometry has nonlinear properties. Various types of nonlinearities are possible.
Member Hinge with Nonlinearity
It is possible to assign nonlinear hinges to member ends. For the pushover analysis, the standardized hinges for steel according to FEMA 356 [1] with plastic criteria are particularly suitable. They describe the ratio of the occurring moment to yield moment, and the occurring rotation to yield rotation. The work line depends on the yield strength of the cross-section.
As an alternative, you can use hinges of the Diagram type with user-defined acceptance criteria. However, nonlinear properties can also be described in the form of a regular member hinge by defining it as a diagram.
However, nonlinear properties can also be described in the form of a regular member hinge by defining it as a diagram. The modal analysis is a linear calculation without considering nonlinearities. Therefore, it is important to define the plastic hinges without fully pinned hinges for the linear calculations (see the image Assigning Plastic Hinge According to FEMA 356).
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Nonlinear Material Properties
The pushover analysis is also able to consider nonlinear material behavior. For example, you can use the Masonry material to determine the pushover curve.
You can also define user-defined materials using the work lines of their own. The Isotropic Damage material model is particularly suitable for this. Find detailed information about this material model in this technical article.
Using user-defined working lines requires a license of the Nonlinear Material Behavior add-on. This add-on is described in the chapter Nonlinear Material Behavior of the RFEM manual.