EXPERIMENTAL AND PARAMETRIC RESEARCH ON THE BEHAVIOR OF CFS-ZEE SECTION UNDER CYCLIC LOAD

Abstract

This research investigated the axial performance of Cold-Formed Steel, CFS thin-walled Zee sections under cyclic pure axial loading. The experiment studied a zee section with a depth of 200mm and a thickness of 2mm. The experiment program was conducted for three full-scale specimens to examine the three buckling failure modes: local buckling, distortion buckling, and global buckling modes with a length of 600mm,1000 mm, and 2500mm, respectively. The Zee-section web is provided with a notch in the distortion and global buckling specimens to prevent the local buckling formation in the web. The energy dissipation with strength degradation behavior of the Zee section was examined for the three buckling failure modes. The cyclic load-displacement protocol was performed according to the FEMA 461 method depending on the elastic properties of the CFS section. The results showed the failure mode of the CFS zee elements and investigated the axial load-displacement responses and axial load capacity. A Finite Element Model FEM was conducted and validated by the experimental results. The FEM analysis was extended to study the behavior of the cyclic Zee sections with wide ranges of Zee-sections’ geometry, including the lip depth, flange width, and thickness.