In the case of structures with a mode shape, which is characterized by a lateral displacement, the effect of imperfections can be considered for the structural calculation by a global initial sway imperfection (and individual bow imperfection, if necessary).
The global initial sway imperfection Φ is determined according to Equation (5.5):
Φ = Φ0 · αh · αm
The resulting basic value Φ0 is equal to 1/200, as specified in DIN 18800, and can be reduced by two factors. These factors take into account the favourable effects of very high columns as well as several supporting columns in a row. The background to this is that the imperfections are structurally distributed and thus very unlikely to be unfavourable on all components.
αh is the reduction factor for the height h applicable to columns
αm is the reduction factor for the number of columns in a row
m is the number of columns in a row with a vertical load > 50 % of the average value of the column
Compared to DIN 18800, there are greater sway imperfections in the case of a larger number of columns m and higher columns resulting from the calculation according to EN 1993-1-1.
.png?mw=600&hash=49b6a289915d28aa461360f7308b092631b1446e)
