Simplified Analysis of Frame-Tube Structures

A simplified method is presented for the analysis of framed-tube structures subjected to lateral loads. The rigidly jointed perimeter frame panels are replaced by equivalent orthotropic plates, whose properties are chosen to represent both the axial and shearing deformation characteristics of the frames. The force and stress distributions in the panels are assumed to be represented with sufficient accuracy by polynomial series in the horizontal coordinates, the coefficients of the series being functions of the height only. The unknown functions are determined from the principle of least work. The influence of stiffer corner columns is included in the analysis. Closed-form solutions are presented for three standard load cases, a uniformly and a triangularly distributed load, and a point load at the top. Design curves are presented to enable solutions to be obtained rapidly.