Under-strength connections: Mu < My
In this situation, the performance of the compound element is governed purely by the semirigid connection, and no inelasticity occurs in the vicinity of the member end. This may occur for single web-angle (SWA) connections with Mu = MuSWA. The combined moment-rotation behaviour of the compound element is shown in Figure 5, which is exactly the semirigid behaviour shown in Figure 4(b). This kind of connection is referred to as an Under-strength connection since the strength capacity of the compound element is less than the yield strength of the member. If Mu is small enough or the rotational constraint is ignored, this type of connection is categorized as a conventional simple or pinned connection (AISC 2001, CISC 2004).