This paper summarizes the seismic analysis and rehabilitation design of a 15‐story steel moment‐resisting frame building constructed with connection details that were found to be vulnerable to fracture in the 1994 Northridge earthquake. This building is located in Oakland, California, less than 5 miles from the Hayward Fault. Previous testing of the existing moment connections demonstrated that the beam flange to column flange complete joint penetration groove welds were vulnerable to fracture, and consequently, the building presented a risk to life safety in the event of a major earthquake. Seismic rehabilitation to meet the requirements of the State of California, Department of General Services resulted in a retrofit scheme, including a combination of moment connection strengthening and addition of viscous dampers. Because of the deep W27 column and very large W36 beam sections present in the special moment‐resisting frames, a series of four full‐scale tests were conducted to evaluate the performance of the proposed rehabilitation schemes. Sophisticated analysis techniques were performed in the rehabilitation design, including nonlinear time history analyses. These models included a nonlinear fiber element that approximated the fracture behavior observed in the existing connection tests and incorporated results from the test program to model the strengthened connection behavior. Copyright © 2011 John Wiley & Sons, Ltd.