A PROPOSAL FOR IN-PLANE STABILITY DESIGN OF STEEL FRAMED STRUCTURES

One aspect not considered seriously in the revisions of the structural steel design codes is the adoption of design analyses where the use of computers is presupposed. A procedure to determine effective length is presented for in-plane stability failure of frames by utilizing eigenvalue analysis of the tangential stiffness matrix, for which the use of computers is essential. Determination of the effective lengths by the eigenvalue analysis encounters one difficulty when there exist members in a frame subject to very small amounts of internal compression. The load carrying capacity of the frame could be determined by these members resulting in unrealistically small capacity. This difficulty was overcome by introducing an amplification factor concept. The proposed procedure is clear and applicable for any frame including one with non-prismatic members.