Local Instability Tests of Plate Elements Under Cyclic Uniaxial Loading

An experimental study of the inelastic cyclic load‐deformation behavior of welded built‐up square box‐section short columns subjected to cyclic axial loading is presented. A total of 10 test specimens were fabricated from mild $({\sigma }_y=240N/{\mathrm{mm}}^2)$ and high strength $({\sigma }_y=700N/{\mathrm{mm}}^2)$ steels, having plate elements with the width‐thickness ratios of 40, 60 and 80 for mild steel, and 40 and 60 for high strength steel. Furthermore, monotonically increased loading tests were carried out for comparison with the deformation behavior of cyclic loading tests. This paper emphasizes the development of alternating local instability of plate elements associated with cyclic loading sequences. The hysteretic loops of average stress versus axial strain curves are expressed experimentally, and analyticalinterpretations are added to the results. Successive reduction of the ultimate strength and residual deformation at zero‐load are provided experimentally and analytically under cyclic loadings.