Cyclic Quasi-Static Testing of Hollow Structural Section Beam Members: Fid-Bau Portal

Cyclic Quasi-Static Testing of Hollow Structural Section Beam Members

Fadden, Matthew / McCormick, Jason

Abstract

The efficient compression, torsion, and bending behavior of hollow structural sections (HSS) combined with their high strength-to-weight ratio provide an opportunity to further their use in seismic applications and improve on structural performance. However, current applications of HSS in seismic systems are restricted because of a limited understanding of their cyclic bending behavior. To characterize the behavior of HSS under pure bending and determine limiting values for their use up to large rotation levels, 11 different HSS beam members ranging in size from HSS $203.2 \times 101.6 \times 6.4 mm$ to HSS $304.8 \times 152.4 \times 6.4 mm$ with thickness of 6.4 and 9.5 mm are tested under cyclic bending loads. The moment-rotation results suggest that the width-thickness and depth-thickness ratios are important in determining whether a stable plastic hinge can be sustained during cycling, ensuring adequate ductility. Cycling effects associated with increasing rotation levels and multiple cycles at the same level are considered with respect to the degradation of the moment capacity, rotation capacity, secant stiffness, and energy dissipation. It is clear that the influence of the width-thickness ratio and depth-thickness ratio is not independent of one other. Flange strains also provide an understanding of how yielding propagates along the length of the member and at what point local buckling begins to occur. In general, the findings suggest that HSS can be used in cyclic bending applications provided that their parameters are selected carefully to ensure stable plastic hinging behavior.