Steel Frame Analysis and Connection Shear Deformation

Rigid moment-resisting connections in unbraced framed structures are shown to have a significant effect on the strength and stiffness of such frames, and a method is provided whereby the size and stiffness of connections are considered in the analysis. The stiffness method of analysis is extended to consider the deformation of the connection. The elastic-plastic response of the connection subjected to antisymmetrical loading is calculated by considering the shear stiffness of the panel in the elastic range and the frame action of the boundary plates (flanges and stiffeners) in the inelastic range. Using the method described, the effect of connection shear stiffening on the frame strength and resistance to drift may be determined. In one experiment in which the girder depth-to-story height ratio was 1:8 and the column depth to girder span ratio was 1:20, the conventional method of analysis erred by 32%; whereas, the panel hinge method predicted the observed behavior accurately.