Review of force transfer mechanism of welded steel moment connections

Abstract

Employing the classical beam theory for the design of welded steel moment connections has been brought into question since the 1994 Northridge earthquake. In this study, the force transfer mechanism in various welded steel moment connections is comprehensively reviewed based mainly on the authors recent studies. Available analytical and experimental results showed that the beam theory does not give accurate predictions of the stress path in almost all the welded steel moment connections because of the effects of the boundary conditions. Vertical plates near the connection, such as the beam web, the web of the straight haunch, and the rib, act as a strut to some extent. The force transfer mechanism in the reduced beam section (RBS) connection is essentially the same as that in the pre-Northridge type connections. Some simplified analytical models that can be used as the basis of a practical design procedure are also briefly presented.