Recent studies provided opportunities to review some of the principles, which have been used in the formulations of internationally accepted code-recommendations relevant to the seismic design of ductile buildings also subjected to torsional phenomena. With the progress of this study, features emerged which are considered to have contributed to a better understanding of structural behaviour. Moreover, the identification of deeply embedded fallacies, relevant to ductile response, suggested the introduction of some changes in seismic design strategies, yet not widely known or appreciated. Reasons for necessary re-interpretations of traditional structural properties, together with illustrative examples, demonstrating applications, rather than set code-type rules, are offered. Keywords: Component behaviour, displacements, ductility, seismic response of buildings, seismic torsion, walls. 273 J. Earth. Eng. 2001.05:273-308. Downloaded from www.worldscientific.com by UNIVERSITY OF CALIFORNIA @ SAN DIEGO on 06/01/15. For personal use only. J. Earth. Eng. 2001.05:273-308. Downloaded from www.worldscientific.com by UNIVERSITY OF CALIFORNIA @ SAN DIEGO on 06/01/15. For personal use only. J. Earth. Eng. 2001.05:273-308. Downloaded from www.worldscientific.com by UNIVERSITY OF CALIFORNIA @ SAN DIEGO on 06/01/15. For personal use only.where E c is the modulus of elasticity of the concrete and I g is the second moment of the gross concrete area. J. Earth. Eng. 2001.05:273-308. Downloaded from www.worldscientific.com by UNIVERSITY OF CALIFORNIA @ SAN DIEGO on 06/01/15. For personal use only.