In the context of seismic analysis of structures, various earthquake inputs may be required depending upon the nature of analysis being carried out. The response spectrum of an earthquake is the most favored seismic input for earthquake engineers. A displacement response spectrum is the plot of maximum displacement of a single degree of freedom system (SDOF) to a particular ground motion as a function of the natural frequency and damping ratio of the SDOF. Present code plots the response spectrum for the given seismic input. Response spectrum is plotted for EL-centro earthquake with 2% damping.