ABSTRACT
In addition to experimental testing, there have been several studies to address the behavior of HSS members using Finite Element Modeling (FEM). Nakashima and Liu (2005) used FEM to study HSS columns up to failure with varying axial loads finding that the amount of axial load greatly affects the hysteretic behavior. Another FEM study modeled large HSS columns with a threesurface cyclic metal plasticity model providing very accurate hysteretic results when calibrated to experimental data (Goto et al. 1998). Other HSS models consider their use in CFT columns under cyclic loading by employing fiber elements which utilize constitutive models for both the concrete and steel that include confinement of the concrete core and cyclic local buckling of the steel tube (Denavit et al. 2010). Modeling of HSS beam sections under monotonic loading has also been
1 INTRODUCTION
1.1 Background
The use of Hollow Structural Sections (HSS) for Seismic Moment Resisting Frame (SMRF) applications has been limited partially due to a lack of understanding of the behavior of HSS under large cyclic rotations. HSS have many desirable properties that have initiated interest in the use of these sections in SMRF systems. Up to now, HSS members typically have been used as columns, truss elements, bracing members, and cladding supports. This is due to their highly efficient compression, bending, and torsional properties. In low and mid-rise SMFR systems, the use of HSS can allow for a possible reduction in weight, decrease in lateral bracing requirements, applications in modular construction, further use in steel-concrete composite systems, and increased interest as architecturally exposed elements. However, increased use of HSS in SMRF systems requires an understanding of their cyclic bending behavior because of strong column-weak beam requirements. Since this mechanism requires most of the inelastic behavior to occur in the beam member, HSS in HSS-to-HSS moment connections must be able to form stable plastic hinges up to large rotation levels.
