Gross bending deformation of hollow and void-filled square tubes

Experimental results of hollow and void-filled square steel tubes subjected to four-pointloading pure bending tests are described and compared to theoretical curves. The specimens tested included both commercially available SHS and spot-welded closed-hat sections manufactured from sheet steel. Results confirm earlier work by Grzebieta and White (1994) on cantilever beams, that void-filled tubes with large width (B) to wall thickness (t) ratios display substantial increases in both bending moment capacity and energy dissipation rates when compared to hollow profiles. In this paper, however, results from a more extensive range of B/t ratios of beams subjected to pure bending, indicate that there is little or no benefit in regard to increased moment capacity or rate of energy dissipation for stocky (thick-walled) void filled profiles. Good correlation between theoretical and experimental values verify useful equations for estimating the peak and residual strengths of both hollow and void-filled beams subjected to pure bending. Plots comparing peak loads, residual loads and energy dissipated for particular B/t ratios will provide useful information to designers wanting to utilise void filling materials to increase strength to weight ratios and energy dissipation rates of thin-walled beams.