The performance of two passive friction damping systems for retrofitting steel moment-resisting frames is evaluated. Nonlinear dynamic analyses were performed on a six-storey moment-resisting frame designed according to cWTent code provisions for California. The structure was subject~d to three different earthquake ensembles. The first ensemble includes six near field records developed for major crustal earthquakes in California. The five records of the second ensemble are representative of near-field conditions in Los Angeles with a probability of exceedence of 10 % in 50 years. Finally, the third ensemble contains two far-field historical records. Both friction systems are part of a steel chevron-bracing configuration used to retrofit the momentresisting frame. In the first system, slotted-bolted connections that slip at a predetermined load are provided at one end of the bracing members. The second system includes double-acting ring-spring friction devices installed at the same locations. The main feature of the ring-spring system i~ a bi-linear hysteresis with a re-centering force that develops upon unloading and contributes in limiting permanent deformations. The slip load of the devices was determined based on a proposed procedure that takes into account the frequency content of the ground motions and the dynamic properties of the str\lcture with and without the added bracing system.