This model is, in a sense, the opposite of the kinematic model. Plastic deformation in one direction “pushes” the curve for the other direction away from it, so that both directions increase in strength simultaneously. Unlike the BRB hardening model, the backbone curve itself does not increase in strength, only the unloading and reverse loading behavior. Matching pairs of points are linked. No additional parameters are required for this model.
Unloading and reverse loading occur along a path parallel to the elastic line until the magnitude of the action in the reverse direction equals that of backbone curve at the same amount of deformation in the reverse direction, and then continues along a horizontal secant to the backbone curve.
When you define the points on the multi-linear curve, you should be aware that symmetrical pairs of points will be linked, even if the curve is not symmetrical. This gives you some control over the shape of the hysteretic loop.
This model dissipates the most energy of all the models. This behavior is illustrated the figure.
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