AISC LRFD 1.pdf

Comm. C2.] FRAME STABILITY 191Notes for Fig. C-C2.2a and b: The subscripts A and B refer to the joints at the two ends of the columnsection being considered. G is defined asIcLcG = Σ ( / )Σ( I / L )in which indicates a summation of all members rigidly connected to that joint and lying on theplane in which buckling of the column is being considered. I cis the moment of inertia and L cthe unsupportedlength of a column section, and I gis the moment of inertia and L gthe unsupported lengthof a girder or other restraining member. I cand I gare taken about axes perpendicular to the plane ofbuckling being considered.For column ends supported by but not rigidly connected to a footing or foundation, G is theoreticallyinfinity, but, unless actually designed as a true friction-free pin, may be taken as “10” forpractical designs. If the column end is rigidly attached to a properly designed footing, G may beFig. C-C2.2a. Alignment chart for effective length of columnsin continuous frames – Sidesway Inhibited.gLRFD Specification for Structural Steel Buildings, December 27, 1999AMERICAN INSTITUTE OF STEEL CONSTRUCTIONg