09-10-2014, 03:02 PM
Currently, designers incorporate secondary effects in the design of frame columns in two ways, namely through effective length factors to account for buckling and through moment amplification factors to account for excessive bending. The design tools to estimate these factors are based on assumptions, which may not even be actually realized. A literature search is conducted to identify the critical parameters that were omitted, or incorrectly considered, in the current methods. The effect of these parameters involved is studied through a new Column Behaviour Model. A simple method for determining the effective length factors of general frame members is presented. Convenient design charts are proposed to obtain effective length factors. When bending moments are present with axial load in a frame member, closed-form expression for the moment amplification is derived for the direct use of designers. Methods of incorporating secondary effects in the design of general frame members with partial restraints against rotation and translation at their ends, are presented. This s