Optimum range of slenderness ratio of hollow steel square braces for special concentrically braced frames

Abstract

Past studies have shown that the slenderness ratio and the width-to-thickness ratio of braces are primarily responsible for achieving the desired cyclic response of special concentrically braced frames. An increase in brace slenderness ratio results in a reduction in its energy dissipation capacity along with a simultaneous increase in the ductility nearing its fracture. Since both energy dissipation capacity and ductility of braces are essential parameters in quantifying the seismic performance of special concentric braced frames, there is a need of establishing the optimum range of brace slenderness ratio and width-to-thickness ratio. Hence, an extensive finite element parametric study has been conducted on a wide range of values of these parameters on braces of hollow steel square section using a commercial software ABAQUS. The finite element models account for the inelastic hysteretic characteristics and the fracture behavior of braces. The results of simulation models matched very well with the past experimental results with respect to the performance points, namely, global buckling, local buckling, fracture initiation, complete fracture, and ductility. Finally, a relationship between the lower limit of slenderness ratio and the width-to-thickness of square braces has been established based on the simulation results.