How does ideCAD control the torsional Irregularities, according to ASCE 7-16, for two earthquake directions?
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Δavg Δavg = Average reduced relative storey story displacement on i'th floor of the building
Δmax Δmax = Maximum reduced relative storey story displacement on i'th storey story of the building
Δmin Δmin = Minimum reduced relative storey story displacement on i'th storey story of the building
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1a - Torsion Irregularity
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The case where the Torsional Irregularity Factor, which is defined for any of the two orthogonal earthquake directions as the ratio of the maximum story drift at any story to the average relative story drifts at the same story in the same direction, is greater than 1.2. Maximum story drift, computed including accidental torsion with Ax =1.0. Torsional irregularity requirements in the reference sections apply only to structures in which the diaphragms are rigid or semirigid.
This type of irregularity affects affects the Selection of Linear Calculation Method described described in Section 12.6 of ASCE 7-16. However, ideCAD Static have has already used Linear Dynamic Analysis (Modal response analysis and modal superposition method in time domain) specified in Section 12.9.
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1b. Extreme torsional irregularity
The case where the Torsional Irregularity Factor, which is defined for any of the two orthogonal earthquake directions as the ratio of the maximum story drift at any story to the average relative story drifts at the same story in the same direction, is greater than 1.2. Maximum story drift, computed including accidental torsion with Ax =1.0.
Extreme torsional irregularity requirements in the reference sections apply only to structures in which where the diaphragms are rigid or semirigid.
According to Table 12.3-1, the calculation of the relative storey story drifts is made are calculated according to the the Equivalent Earthquake Load Method, taking into account considering the + - 5% eccentricity effects. While linear dynamic analysis are is used in the earthquake calculation of the building, Equivalent Earthquake Load Method is is used in1a in 1a and 1b type irregularity control.
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