In this article nonlinear behavior of multi-story asymmetric buildings is evaluated considering history of combinations of story shear and torsion in a space called SST (Story Shear and Torque Surface). The first step for understanding this behavior, in modifying these surfaces that represent all combinations of story shear and torque that applied statically to the structure and produce mechanisms in the story. Many factors influence the shape of the SST surface that effects of some factors such as strength of resisting planes in orthogonal direction, strength eccentricity and stiffness eccentricity is considered and their effects on the behavior of asymmetric buildings in evaluated considering 5, 8 and 12 story buildings. Results show that the SST surface with conjunction of the history of shear and torsion in stories produces a useful framework for understanding the behavior of asymmetric systems. Additionally, it is possible to predict the behavior of an asymmetric system using these surfaces even before any dynamic analysis. This method is applicable in both steel and concrete structures.
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