In this paper, a pseudo-single-degree-of-freedom system identification procedure is developed to investigate the dynamic characteristics of energy-dissipated buildings equipped with symmetric ductile braces (SDBs). The primary structure is assumed to be linear on account of substantial reduction of seismic forces due to the installation of SDBs for which a bilinear hysteretic model is considered. The hysteretic model is in turn characterized by a backbone curve by which the multi-valued restoring force is transformed into a single-valued function. With the introduction of backbone curves, the system identification analysis of inelastic structures is significantly simplified. The proposed algorithm extracts individually the physical parameters of each primary structure and each energy-dissipation device that are considered useful information in the structural health monitoring. A numerical example is conducted to demonstrate the feasibility of using the proposed technique for physical parameter identification of partially inelastic energy-dissipated buildings.