A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Engineering and Technology

Thesis (M.Eng.) - Asian Institute of Technology, 1985

A simple design procedure for the compression members and frames by utilizing eigen-value analysis is proposed in this thesis. Effective lengths are defined at each section of framed structures, and the check of structural safety at each section is presented by utilizing the effective length defined in this study. This procedure is more advantageous compared with the clauses given in current design codes, Especially for members subject to nonuniform bending moment distribution, and for members with variable cross section. Numerical examples are worked out to compare the design based on the proposed procedure and the specified in the design code of the American Institute of Steel Construction. The Results show that the effective length determined by utilizing eigen-value analysis can predict the structural behavior more precisely for structures under a variety of loading condition. One of the problems in the evaluation of the effective length by this proposed design procedure is that for members under very small axial compressive force which results in large effective lengths and this might result in unreasonable large sections for these members. This problem is also reviewed in view of optimum design in this thesis.