Evaluation of HSS-to-HSS Moment Connections for Seismic Applications

Hollow structural sections (HSS) are currently underutilized in seismic applications in structures. To address this, a connection design methodology is derived for both unreinforced and reinforced, fully welded, HSS-to-HSS moment connections. Experimental testing of two unreinforced HSS-to-HSS connections with unmatched and matched beam and column widths is conducted under cyclic loads to failure. The hysteretic behavior shows that these connections are limited in their ability to isolate inelasticity to the beam member and panel zone region. A finite element parametric study also is used to better understand the effect of different parameters on internal and external reinforced HSS-to-HSS connection performance under cyclic loads. Based on the finite element models, reinforced connections show the ability to develop plastic hinging in the beam members with a normalized moment capacity greater than unity.