
Eigenvalues
For every eigenmode the respective response spectrum is analyzed and the deformations, internal forces, etc. are saved. In order to evaluate the modes of vibration to be considered, the applied masses are contrasted with the effective modal masses.
Soil Acceleration
The soil acceleration is applied according to the earthquake zone. When doing so, the direction can be applied for individual components and superposed at a later time (for instance: ± 1.0 Edx ± 0.3 Edy). If necessary, the frame of reference can be rotated into the local building axes.
Coefficients According to DIN 4149:2005
The selected subsoil conditions determine the parameters for the horizontal and vertical response spectra. These are then analyzed and superposed under consideration of the structural properties. The program selects the required static superposition (SRSS or CQC) in accordance with the standard. The user can optionally override this selection.

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Depending on the period of oscillation, the relating spectral acceleration can be taken directly from the response spectrum (for instance, for determining the foundation shear). |
To allow for further analysis (for instance, calculation according to the deflection theory), the static pseudo loads associated with the modal components can be saved.
 Static pseudo load of the 1st eigenmode
Literature:
DIN 4149, Edition:2005-04 Bauten in deutschen Erdbebengebieten - Lastannahmen, Bemessung und Ausführung üblicher Hochbauten (Buildings in German Earthquake Areas - Design Loads, Analysis and Structural Design of Buildings) Beuth Verlag GmbH
Meskouris, K. (1999) Baudynamik (Structural Dynamics) W. Ernst & Sohn, Berlin |