Inelastic Response of Restrained Steel Tubes

Eighteen specimens made from 1 in. (25-mm) square tubes with welded gusset plates were tested under repeated axial loading. Length of the specimens varied from 20 in. to 54 in. (510mm to 1,370mm) and their slenderness ratio varied from 30 to 160. The objective of this investigation was to study the effects of connection flexural strength and stiffness and change of member length on the hysteresis behavior. From the parametric study it was concluded that the hysteresis behavior of flexurally restrained axial members is most influenced by a single parameter — the effective slenderness ratio. The results were compared with recent theoretical predictions and were in excellent agreement for members of larger slenderness ratio, yet with some slight differences. Other observations are that the maximum compressive load decreased and member length increased with number of cycles.