| Notetip |
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As required by 12.8.4.2, the earthquake calculation is made automatically in every 4 cases by shifting the storey masses by 5%. |
| Notetip |
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In accordance with 12.8.4.2, the horizontal earthquake loads are calculated automatically by shifting (+) and (-) 5%. |
| Info |
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In modeling accidental torsion, any of the static and dynamic methods that comply with the regulation can be used for analysis. Method selection is under user controlcontrolled by users. |
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There are two different ways to determine the additional eccentricity effect.
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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 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.
Why is accidental torsion applied?
It is calculated by one of the methods mentioned above in accordance with 12.8.4.2 of ASCE7-16 .
The buckling moment of the structure due to ground motion can affect the Z axis.
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.
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