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This type of irregularity affects the Selection of Linear Calculation Method described in Section 4.6 of TBDY . According to Table 4.4 , if the Torsional Irregularity Coefficient η bi value is less than 2, the Equivalent Earthquake Load Method can be used. However, ideCAD Static TBDY uses the Modal Calculation Methods and Linear Earthquake Calculation specified in Section 4.8 (Mode Combining Method Modal Response Spectrum Analysis andMode Addition Method in Time Domain ). Therefore, if the building contains B2 type irregularities,Modal Calculation Methods and Linear Earthquake Calculationaccording to 3.6.2.1 are valid.
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According to Table 3.6 , the calculation of the relative storey drifts is made according to the Equivalent Earthquake Load Method described in Section 4.7 of TBDY, taking into account the effects of + - 5% eccentricity . While Modal Calculation Methods are used in the earthquake calculation of the building, Equivalent Earthquake Load Method is used in B2 type irregularity control.
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