ACCOUNTING FOR CONNECTION BEHAVIOR IN STEEL FRAME DESIGN

The behavior of a steel frame may be affected significantly by the moment versus rotational deformation (M-phi) behavior of its beam-to-column connections. Some of the effects of connection behavior are described and demonstrated. Because connection behavior is nonlinear and relatively difficult to model analytically, generally applicable analytical behavior models are not available. Nor, despite the availability of more than 300 experimentally measured connection M-phi data sets, are generally applicable empirically based behavior models available. Consequently, connection behavior continues to be accounted for only crudely in North American design specifications and in frame design. This paper describes a three-step strategy that would eventually permit the M-phi behavior of beam-to-column connections to be accounted for explicitly and routinely in steel design specifications and thus in frame design. The first step, to express connection M-phi behavior in a compact form suitable for incorporation into frame analysis software, has been demonstrated by curve fitting 274 experimental M-phi data sets to a specially developed function that requires only six parameters to describe connection behavior. The second step, to illustrate graphically the ranges of M-phi behavior exhibited by the common connection. types, and thereby to help designers to develop a ''feel'' for connection behavior, has been demonstrated by comparing the M-phi plots to the EUROCODE3 connection classification boundaries. The third step, to blend the standard connection geometries that have been developed in several countries into an international menu of standard connection geometries and, eventually, to generate and curve fit reliable experimental M-phi data for all of the standard connections, is summarized.