Parametric study and design of rib-reinforced steel moment connections

Seismic behavior of moment connections used in moment-resisting frames can be improved by adding vertical ribs to beam-to-column joints. A parametric study is conducted here to investigate effects of design parameters of the rib on the connection behavior. Three geometrical parameters were set for the rib characterized with an extension. Moreover, nonlinear finite element analysis was used for the parametric analysis. The stress distribution and plastic strain demand for various combinations of these parameters are also presented and compared. The numerical results indicate that a single lengthened rib can eliminate the concentrations of stresses and strains found in the unreinforced connection, and reduce the potential for brittle fracture of the connection. On the basis of the numerical results and the confirmation of previous experiments, rib design variables are recommended, along with a design procedure.