Restoring Force Model of an Energy-Dissipation Joint in Hybrid Frames: Simplified Skeleton Curve and Hysteretic Rules

Table 3

Three working stages of a typical skeleton curve.

Working stages	relationship	Working status of EDP	Working characteristics [28]
I	Linear	Elastic	No damage of each components
II	Nonlinear curve	Buckling	By increasing the displacement or load, the strain exceeds its elastic limit, and the EDP of the joint begins to buckle
III	A segment with negative stiffness	Failure	At the end of stage (II), the higher the displacement, the lower the load until the failure of the joint occurs