Minimizing the torsional response of inelastic multistory buildings with simple eccentricity

Common types of multistory buildings, detailed according to a planar static analysis under a code lateral loading, may have a practically translational behavior when the mass axis is passing through (or within a close distance from) the modal centre of rigidity (m-CR). The concept of this point in elastic multistory structures was introduced by the author in earlier papers, but it retains its value in structures composed by inelastic bents, since it specifies the optimum arrangement of these structural elements in terms of producing minimum torsional response in the case of a strong ground motion. This is demonstrated in typical five story buildings, composed by moment resisting frames and structural walls, under the ground motions of Kern County and Loma Prieta.