Seismic Behavior Assessment of Special Concentrically X-braced Frame with Through Gusset Plate

Abstract

Concentrically braced frames exhibit adequate stiffness against lateral loads. However, a critical issue with these frames lies in the connection between the brace and beam/column. The compressive and tensile forces in the braces induce significant shear at the end of the beam, leading to yielding of the beam and failure of the connection to the column. Additionally, in many cases, welds at the edge of the gusset plate to the beam experience premature failure due to stress concentration before brace yielding or buckling. In this study, it is proposed to replace the I-shaped beam with a double channel beam (2-UNP) and to allow the gusset plate to pass continuously through the beam. Consequently, in consecutive stories, there will be a continuous connection plate passing through. The research results demonstrate that in this configuration, the stress level in the beam web, connection of the beam to the column, and weld at the edge of the connection plate are significantly reduced. In frames with through gusset plates, as a portion of the brace force is transferred through the connection plate passing through the U-shaped beam, less force is absorbed by the weld, preventing premature brace yielding or buckling before weld failure. Furthermore, due to increased allowable drift in frames with through gusset plate, the ductility of the frame enhances compared to frames with a conventional gusset plate.