Influence of a cutout on circular steel hollow sections under cyclic loading

• With an optimal cutout, the stress concentration was significantly relieved.
• Fatigue life of the specimens dramatically increased with a proper cutout.
• A significant amount of stress concentration was developed near a small hole.
• For very large holes the influence of the cutout on the fatigue was quite negative.
• There is a strong interrelation between the strain values of Scutout and Sweld.

Due to extensive applications of circular hollow sections (CHS) as structural members, these steel elements are always in the focus of interest of investigators. This study reports on the effect of circular openings on the fatigue behavior of CHS members. Circular cutouts were made near the area of maximum tension stress of tube specimens. The failure mode as well as the fatigue life was explored. It was found that fatigue life and failure modes strongly depend on the position and the diameter of the opening. It was interesting that, due to the distribution of the stress concentration, a cutout with an optimal diameter helped to extend the fatigue life of a tube compared to those without the cutouts.