8B. ANALYSIS PART 2

CHAPTER 8B 'ANALYSIS' 40 CAN §5.7.2 (b) INFLUENCE OF THE HIGHER IDIOMORITIES A further check is contained in paragraph 5.7.2(b) of the EIA and concerns the influence of the higher eigenmodes . The CAN states that for pushover to apply, the influence of the higher eigenmodes must be insignificant. The criterion for assessing how significant the influence is is as follows: In order to check this condition, an initial dynamic elastic analysis is required where the seismic shear stress is calculated, for each floor and for each direction of the earthquake, once for those eigenmodes that activate at least 90% of the building mass and once for the fundamental (per direction) eigenmodes. OBSERVATIONS The influence is considered significant when, even on one floor and in one direction, the ratio of the intersection of several eigenmodes (Vall) to the intersection of one eigenmodes (V1) is greater than 1.3. This criterion was only incorporated in the Dynamic analysis scenarios. The results are shown in three locations: In the graph within the analysis by selecting "Upper Eigenmode Influence Check" As tabulated results by selecting "Seismic Action"