The use of energy-based method is discussed in this paper, with taking into account the gravity effects, P-∆ effects, and other equations to prevent the formation of undesirable mechanisms. In this method the seismic design forces are derived from input energy for a selected plastic yield mechanism, and a selected target deformation level. The aim of this method is to study the ability of predicting structural behavior in the ultimate level and to use the maximum structure capacity in order to dissipate seismic input energy. For comparison between response of structures designed with equivalent static method and energy-based method, two 10 and 15-story steel moment frames are designed considering these two methods, for which the results from nonlinear analyses of the frames are compared. The obtained results indicate that the seismic design by energy-based method improves the seismic behavior of structures compared to the typically used equivalent static method.