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 EN 1998-1:2004
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.
 |
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 second-order theory), the
static pseudo loads associated with the modal components can be
saved.
Static pseudo load of the 1st eigenmode
Literature:
Eurocode 8: Design of structures for
earthquake resistance –
Part 1: General rules, seismic actions and rules for buildings
EN 1998-1:2004
Beuth Verlag GmbH
Meskouris, K. (1999)
Baudynamik
(Structural Dynamics)
W. Ernst & Sohn, Berlin |
