The validity of the EC3 classification system for connections is reviewed by examining the elastic-plastic overall critical behaviour of frames. As a result, it is observed from the numerical results that the semirigid frames exhibit a load-carrying capacity almost comparable to that of rigid frames even when the connection rigidity of the semirigid frames is much lower than that specified by EC3 as the boundary between rigid and semirigid. This implies that the EC3 requirement for the connections to be classified as rigid may be rather restrictive in terms of the load-carrying capacity of frames. In addition to the EM classification system, some comments are also made on the other classification system proposed by Bjorhovde et al. © 1995.
Goto, Y., & Miyashita, S. (1995). Validity of classification systems of semirigid connections. Engineering Structures, 17(8), 544–553. https://doi.org/10.1016/0141-0296(95)00013-W