Analysis of Flexibly Connected Steel Frames

Abstract

A procedure is presented for analyzing steel frames with any combination of pinned connections, fixed connections, connections with any specified flexibility characteristics, or any of seven commonly used connection types. A method is outlined for expressing, in a nondimensional form, the moment–rotation characteristics for all connections of a given type. The dimensionless relationships are listed for the commonly used structural steel framing connection types. The incorporation of connection deformations into a linear structural analysis, by modifying the stiffness matrix and fixed-end-force vectors for each member, is demonstrated.An iterative nonlinear analysis procedure is described in which repeated modifications are made to assumed flexibility characteristics for all connections in a structure. When a suitable set of connection flexibility characteristics has been arrived at, a single analysis is performed to determine the correct structural deflections and internal forces.