THE EFFECT OF THE SELECTION OF COLUMN AXES ON THE INTERNAL FORCES

Abstract

In the idealization of structural frames, certain questions require special comments. The most important of these are; the effective span lengths, effective moment of inertia, and conditions of supports. In an elastic frame analysis, a structure is usually represented by a simple line diagram, which is based on the centerline distance between columns and between floor beams. Actually, the depths of beams and the widths of columns amount to sizable fractions of the respective lengths are considerably smaller than their centerline distance between joints. It is evident that the usual assumption in a frame analysis that the members are prismatic, with constant moment of inertia between centerlines, is not strictly correct. A beam intersection with a column may be prismatic up to the column face, but from that point to the column centerline, it has a greatly increased depth, with a moment of inertia that could be considered infinite compared with that of the remainder of the span. In addition, some eccentricities occur on the column axis due to variation of column dimensions and erroneous production. In this study, the effects of the selection of column longitudinal axes at planar frame system structures were investigated.