© 2021 COMPDYN Proceedings.Ductility demands observed in asymmetric plan structures due to earthquake excitations are investigated in this study. Torsional Ductility Spectra are utilized to estimate the maximum ductility response of such systems. Dynamic response of these systems are dominated by the lower vibration modes and observed seismic behavior is in conformance with the capacity design principles. In order to utilize the Torsional Ductility Spectra, five parameters of the asymmetric plan systems, namely, first mode period, uncoupled frequency ratio, stiffness eccentricity, stiff-to-flexible edge strength ratio and ductility reduction factor are estimated through a novel procedure. Simple formulations for representing the dynamic properties of shear frame systems in terms of described structural parameters are developed. Parametric equivalents of shear frame structures are obtained. Estimated ductilities form the developed charts are compared with those obtained from dynamic response analyses of shear frame asymmetric-plan systems. The observed results indicate that developed spectra are able to estimate the ductility demands at both stiff and flexible side frames of actual asymmetric-plan systems with reasonable accuracy. Based on the conclusions, Torsional Ductility Spectra charts are considered practical tools for estimating the ductility demands of asymmetric plan structures.