Estimation of Collapse Strength of Square Tubes with Partition Plate under Bending and Torsional Loadings

Abstract

In this study, estimation of maximum bending and torsional moment for square tubes with vertical partition plate was investigated using nonlinear finite element analysis. Especially, the effects of tube’s geometries on the observed collapse mode, and on the maximum bending and torsional moment were discussed.
When the tubes are subjected to pure bending moment, there are mainly two types of collapse modes, namely, plastic buckling and flattening, and these modes can be distinguished by the amount of the tube thickness-to-width ratio t/a. Also, the flattening deformation can be divided into two modes (Flattening-A and Flattening-B), and the former mode is governed by the decrease of compressive bending stress along the longitudinal axis, and the latter is governed by the decrease of compressive stress along the vertical partition. In addition, the square tube with partition can be regarded as the assembly of two rectangular tubes, and the bending stress distribution spreading in the square tube and the rectangular tube are almost the same with each other. Thus the maximum bending moment for tubes with partition can be estimated by the theoretical result for the rectangular tubes. When the tubes are subjected to pure torsional moment, the effect of partition on the torsional behavior is small, so the maximum torque can be evaluated by that for a tube without partition. Moreover, since the relationship of maximum bending moment and torsional torque of the tubes with partition is equal to that for the tubes without partition, the collapse strength for tubes with partition can be predicted easily from the relationship and the pure bending and torsional results for tubes without partition.