Characteristics of Compound Rotational Element
The behaviour of the compound rotational element is dependent upon the strength capacities of the connection and the connected beam members. For the current study, the effect of connected columns on the behaviour of the beam-column connection is ignored and the shear deformation of panel zones is not considered.
If considering only the effect of member plasticity, the moment-rotation relation in the post-elastic range is as shown in Figure 4(a), whereas when considering the effect of the semirigid connection alone the moment-rotation relationship is as shown in Figure 4(b). In Figure 4, Mu is the ultimate moment capacity of the connection, while My and Mp are the initial-yield and fully-plastic moment capacities of the connected member, respectively. Depending on the interaction of member inelasticity and nonlinear connection behaviour, three types of semirigid connections may be characterized by the compound element, as described in the following.