Civil Engineering Reference
In-Depth Information
Table 7.2
Intensities
(EMS-98) and magnitudes
(Richter scale) of various
earthquakes according to
Mohrbach [
20
]
Earthquake
Intensity, EMS Magnitude, M
Tohoku [2011] (Fukushima)
XI
9.0
Lisbon [1755]
XI
9.0
Basel [1356]
IX-X
6.9
6.25
a
VIII-IX
D¨ren [1756]
VIII
5.9
Roermond [1992]
VII
5.3
a
Ahorner [
17
]
Fig. 7.1
Changes in the
response spectra of a
nuclear power plant in an
earthquake [
21
]
Incoming
tsunami
Building-
ground
Incoming
ground waves
Soil Strata
Solid Rock
Hypocenter
• “Horizontal and vertical accelerations must be assumed to act simultaneously.
The maximum vertical acceleration must be assumed to be 50 % of the maxi-
mum horizontal acceleration.”
The seismic waves change amplitude and frequency-vs.-time characteristics
when impacting local ground strata around the building site of a nuclear power
plant. Figure
7.2
shows such a typical ground response spectrum for horizontal
accelerations as a function of frequency and damping levels, D, of the reactor
building vibrating in the soil strata (the frequency, period, and the damping levels,
respectively, correspond to the theoretical description of a damped spring mass
system vibrating under an external force [
1
]).
Besides the rules proposed (KTA 2201.1 [
6
,
7
]), also two-dimensional and three-
dimensional finite-element models can be employed in mechanical analysis. Mate-
rials in these cases can be modeled either linearly or non-linearly. Various damping
models (viscous or viscous with hysteresis) have been developed. The results
obtained as a function of height in the reactor building are the maximum horizontal
