Finite element model of the cyclic bending behavior of hollow structural sections

• Finite element model for hollow structural sections in cyclic bending is validated.
• 133 hollow structural sections (HSS) are modeled under cyclic bending loads.
• Nearly all HSS show degradation in capacity with cycling due to local buckling.
• Limiting width–thickness and depth–thickness ratios of 12.1 and 28.4 are derived.
• Secant stiffness is more dependent on web buckling than flange buckling.

Hollow structural sections (HSS) are desirable for utilization in structural applications due to their inherent flexural, compression, and torsional properties. These sections are highly efficient, but have been underutilized in cyclic bending applications due to a lack of understanding of their behavior under these loads. To address the limited experimental data and determine potential limiting parameters for the use of HSS in seismic bending applications, a finite element model (FEM) considering experimentally measured material properties, section geometry, and geometric imperfections has been calibrated and validated to experimental findings. A parametric study is conducted on 133 different standard HSS beam members of sizes ranging from HSS 152 × 50.8 × 4.8 to HSS 508 × 305 × 15.9. To provide insight into the parameters that limit stable hysteretic behavior, the decrease in the overall maximum moment capacity with cycling at a given rotation level, rotational capacity at a given degradation of the moment capacity, and decrease of the secant stiffness with cycling are considered. The findings provide information about the interdependence of the width–thickness and depth–thickness ratios on the cyclic bending behavior of HSS. Linear regression analyses provide a relationship between the width–thickness and depth–thickness ratios and member performance from which equations for predicting the degradation of moment capacity and rotational capacity can be defined.