Interstory stiffness irregularity Coefficient ηki, is defined by dividing the average relative storey drift ratio at any ith storey by the average relative storey displacement ratio of the upper or lower storey, except for basements, for either of two earthquake directions perpendicular to each other. Where ηki is greater than 2.0, there is interstory stiffness irregularity at the building.
ηki = (Δi(X)/ hi)ort / (Δi + 1 (X)/hi + 1)ort > 2.0 or
ηki = (Δi(X)/ hi)ort / (Δi-1(X)/hi-1)ort > 2.0
According to Table 3.6, the calculation of the relative storey drifts is made according to the Equivalent Lateral Force Procedure described in Section 4.7 of TBDY, taking into consideration the effects of + - 5% accidental torsion. It is detailed in the earthquake regulation report.
If desired to control this report A1- Torsion Irregularity Control calculated with the aid of data obtained from the excel program interface section Δi,avg need to perform additional calculations using excel value.
There is no B2 type irregularity in the building.