Analysis Modes

The following dynamic analysis modes (regimes) will be presented in this section: Modal,
Seismic, Pseudo mode.
Several seismic codes (UBC-97, French code PS-92) require that sum of masses for each
direction (or for horizontal directions only) should be not less than 90%. Some“hard”
problems may arise, when it is very difficult to achieve the required sum of masses due to
small contributions of a large number of the lowest modes. Usually, this problem is caused by
local character of the lowest modes. The Seismic mode and Pseudo mode are presented to
improve the situation of such difficult problems.

 

 The effectiveness of such approaches is
illustrated by appendix 3C. Lanczos method for direct solvers is available for these two
modes. Modified Lanczos method and PCG_Ritz one are available for pseudo mode, when
iterative solver is selected.