Experimental study on brace to HSS column connection using through-gusset plate

In Hollow Structural Section (HSS) column, webs are available at both ends of column flanges. Thus, there is an offset between webs and a gusset plate connected to the middle of this column flange. However, in H-shaped column, both the column web and the gusset plate are connected to the middle of the column flange. On the other hand, unlike H-shaped column, HSS column flange does not possess an appropriate support and this problem can induce distortion, out-of-plane deformation, and fracture in HSS column flange. To resolve this problem, this study proposes a new gusset plate connection passed through HSS column and called through-gusset plate. Also, force transfer mechanism and design procedure are presented for through-gusset plate. To evaluate the cyclic response of the proposed connection, an experimental study was conducted on two full-scale one-bay, two-story Special Concentrically Braced Frames (SCBFs). This study considered beam-to-column connection as moment transfer via a through-plate to mobilize the reservation capacity of SCBFs. Square-HSS and circular-HSS cross sections were used for braces and columns. The experimental results demonstrated that the proposed connection is acceptable since through-gusset plate can eliminate distortion and out-of-plane deformation of HSS column flange at the gusset plate vicinity via providing a new load path. The cyclic response of specimens showed that beam-to-column moment connection by through-plate increased strength, ductility, and energy dissipation capacity for approximately 41%, 79%, and 110%, respectively. In addition, in the phase of reservation capacity, noticeable slip in bolts and sudden fracture in connection plates occurred. Consequently, an acceptable performance was not observed for beam-to-gusset plate connection proposed in AISC.