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Earthquake Response Analysis
Earthquake response analysis was performed for
the non-isolated and isolated domes. Both the NS
and UD components of El Centro 1940
acceleration records which were normalized such
that the maximum horizontal velocity is 50 kine
were simultaneously inputted as the horizontal
and vertical ground motions, respectively. In
order to investigate the residual displacement of
the isolation system at the termination of the
earthquake, the accelerations were reduced
gradually from 30 seconds approaching zero after
35 seconds. Time domain simulation was based
on the linear acceleration method with a time
interval of 0.01 seconds for duration time of 40
seconds. The viscous damping ratio was assumed
to be 1.5% for the dome and 1.0% for the base
isolation system.
Fig. 4.3 shows the distribution of the maximum
acceleration responses along the x-axis. It is
observed that the large horizontal and vertical
acceleration responses of the non-isolated dome
are reduced drastically by introducing the baseisolation
system. This is because the antisymmetric
vibration modes excited by the
horizontal ground motion are reduced by
introducing the seismic isolation system.
Co-latitude (dec)
Co-latitude (dec)
Vertical acceleration
* Non-isolated|
ees Isolated
FIG. 4.3
MAXIMUM ACCELERATION RESPONSES
ALONG X-AXIS TO EL CENTRO 1940
Fig. 4.4 shows the distribution of the maximum
axial stresses (bending stresses not included) of
1 6 10* 1
-U 10* - L
Displaceraent (cm)
FIG. 4.5
HYSTERESIS LOOP FOR BASE
ISOLATION SYSTEM
Co-latutude
lagonai neabers adjacent to x-axis
FIG. 44
MAXIMUM AXIAL STRESS RESPONSES
TO EL CENTRO 1940