Understanding the trends in torsional effects in asymmetric-plan buildings

Abstract

This paper studied the reasons behind the four trends in torsional effects in asymmetric-plan buildings observed in the current literature. It was found that the modal eccentricities and the non-proportionality between the modal translations and the modal rotation are key to understanding these trends in torsional effects in asymmetric-plan buildings. These key points were obtained from the three-degree-of-freedom modal systems, which represent the single vibration mode of a two-way asymmetric-plan building. This paper showed that the modal eccentricities, rather than the overall structural eccentricities, are the critical parameters for deciding the trend of the unequal displacement demand on the floor diaphragm. In addition, the non-proportionality between the modal translations and the modal rotation leads to the trend that the torsional effects generally decrease when plastic deformations increase. © Springer Science+Business Media B.V. 2012.