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1- Static procedure: For horizontal earthquake loading situations, the torsional moment (MzM_z) obtained by multiplying the storey forces determined by response spectrum analysis by the rate of exanthicity eccentricity is applied to the center of the diaphragm. Regardless of whether the diaphragm type is full or semi-rigid, Torsion Moment is applied to the center of the diaphragm in all floors containing diaphragms. As of V10.15, it is applied if the static eccentricity and single loading state calculation method is selected in the analysis settings tab. Unless a different value is entered in the analysis settings tab, transactions are made according to the (+) and (-) 5% eccentricity ratio in both horizontal directions.

2- Dynamic procedure:  Determined directly for each mode by response spectrum analysis. It is included in the internal force and displacements of the horizontal earthquake loading conditions obtained by combining with CQC  or  SRSS methods. According to the logic of the method, at each node where the masses are distributed, the mass at the center of the diaphragm, for the semi-rigid diaphragm, or the mass at the center of the diaphragm, is calculated by shifting (+) and (-) 5%. Since it is obtained by shifting the mass matrix, 4 different modal analyzes are required in the standard procedure.

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• The locations of the centers of mass and rigidity for a given floor or roof typically cannot be established with a high degree of accuracy because of mass and stiffness uncertainty and deviations in design, construction, and loading from the idealized case. To account for this inaccuracy, the standard requires the consideration of a minimum eccentricity of 5% of the width of a structure perpendicular to the direction being considered to any static eccentricity computed using idealized locations of the centers of mass and rigidity.