Geoscience Reference
In-Depth Information
Fig. 9.15. Load-deformation curves (M-
and M-w) inthe two examined cases under
earthquake loading. The outcropping excitation isalong duration Ricker pulse
(
θ
T
E
=
2
.
2s
,
PGA
=
0
.
20g
)
. The graylines arethe monotonic loading curves
Several conclusions may be drawn fromFigures 9.15 and 9.16:
•
For the light structure
: The initial loading cycle follows the monotonic pushover
M-
curve. Upon unloading after a small excursion in the descending branch of
the monotonic curve, the path follows with small deviations the original monotonic
curve. This is evidence of reversible behaviour—the result of
nonlinearly elastic
upliftingresponse.However,afterasubstantialexcursionintothedescendingbranch
unloading departs slightly from the virgin curve, as soil inelasticity is “activated”
due to the large concentration of the applied normal stress when uplifting reduces
substantially the area of contact.
θ
For the heavy structure
: The departure of all branches of loading-unloading-
reloading cycles from the monotonic curve is far more substantial—apparently the
•
