Stability design of semi-continuous steel frame structures

Stability design procedures for semi-continuous steel frames are summarized herein. The indirect design procedure of semi-continuous frames conforms with the EC3 standard (European Code ENV-1993-1-1 1992). A new set of member stiffness equations for the effective length chart method is developed, taking into account the effect of semi-rigid joints. The member distribution factors are calculated with the use of so-called fixity factors. The direct design procedure proposed in this paper is based on the concept of advanced analysis which assumes the same partial safety factors for load components and sectional strengths as those used in the conventional limit states design method. The effect of semi-rigid connections is incorporated in the form of a Standardized Connection Model (SCM). The difference between the direct and indirect design procedures is that the resistance in the former refers to the complete structural system, whereas the resistance of each individual component is considered in the latter.