A procedure of analysis of inelastic response spectra based on Park and Ang damage model, called damage spectra (or “RD” spectra), is proposed. Considering the ultimate limit state of buildings and using Damage-based Response Spectra (DBRS) program, a series of RD spectra are obtained. RD spectra consider both the effect of maximum inelastic displacement and the effect of cumulative hysteretic energy, fairly according with the actual inelastic behavior due to the strong ground motion. Then, some characteristics of RD spectra are found, which are similar with the former Rμ spectra. Due to lots of time history analysis of SDOF oscillators and regression of datum, an expression of RD spectra is constructed. Furthermore, the proposed RD spectra are compared with Rμ spectra qualitatively. The results of this paper have the smallest values compared to other results because of two main reasons. One is the consideration of the ultimate limit state of structure and the other is the consideration of the influence of the duration of ground motions, which deserve more attention during the seismic design or estimation for the structures.