Link-to-Column Connection with Supplemental Web Doublers in Eccentrically Braced Frames

Abstract

When an eccentrically braced frame configuration requires that the links be connected to the columns, standard seismic guidelines offer little guidance on the link-to-column connection design. Recent testing showed that several welded moment connection details that have been developed after the 1994 Northridge earthquake for special moment frames still cannot prevent brittle fracture in the link flange groove welds. In support of an experimental study on the development of reliable link-to-column connection details, the supplemental web doubler connection is proposed. The connection uses a pair of partial-height doubler plates that are parallel to and offset from the web in the link panel next to the column. Finite-element analyses were conducted to guide the development of design requirements, including the minimum reinforced length, minimum supplemental doubler thickness, and weld design requirement. A closed-form solution, with some minor adjustment based on the finite-element analysis results, for the calculation of the required shear force in the supplemental doublers is also proposed. A step-by-step design procedure is presented.