A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering of the Asian Institute of Technology, Bangkok, Thailand

Thesis (M.Eng.) - Asian Institute of Technology, 1976

Investigated in this study is the elastic-plastic behavior of wide-flange columns in building frames subjected to axial and horizontal loads and external moments at both ends. The column is elastically restrained against rotations at both ends by adjacent beams , and free to sway laterally. The differential equation governing the deflection of the column is derived in a simple form, based on the fixed coordinate system with the origin at the centroid of the original cross section, and proved valid for both the elastic and the elastic-plastic states of loading. The application of the finite difference expression to the governing differential equation and the boundary conditions yields a set of simultaneous equations, the deflection at each subdivision point being unknown. An iterative procedure of the numerical computation is discussed for solving the simultaneous equations which are modified to avoid the situation of non-convergence of the solution in the vicinity of the maximum load. The parametric study reveals that the intensity of the axial load, the column length, the beam-to-column stiffness ratio and the beam stiffness ratio are the main parameters affecting on the column behavior. As a conclusion, simple formulas are derived for the approximation of the maximum load carrying capacity of the column and the deflection at the maximum load, and the results are compared with the actual ones obtained by the numerical analysis.