Geoscience Reference
In-Depth Information
0
-
500
-
1000
-
1500
-
2000
0
5
10
15
20
Time
15
10
5
0
-
5
-
10
0
5
10
15
20
Time
Fig. 10.15. Vertical force and displacement of footing 1
forcesanddownwarddisplacements).Figure10.16plotsthevertical,shearandmoments
appliedtofooting1.Thisshowsthatwhenupliftoccursthehorizontalshearandmoment
are also set to zero. The lower part of the figure has at an expanded scale to show more
clearly the actions during the five upliftevents.
The response of footing 6 is similar. However, footings 7 and 12 had reductions in ver-
tical force and consequent upward movement of the footing but no uplift. Even so there
were some brief periods for footings 1, 2 and 3 during which the bearing strength and
momentdemandexceededthecapacity.AmostinterestingoutcomefromtheRuaumoko
modellingwastheverticalforcehistoryattheinternalfootings,2to5and8to11,exhibit
very nearly constant vertical force during the earthquake motion.
5.4. ELASTIC STRUCTURAL RESPONSE WITHPINNED COLUMN-FOOTING
CONNECTIONS
Modelling of the uplift mechanism is clearly important for the outer footings of this
framed structure. In Figure 10.17 the state paths for footing 1 are plotted with respect
to the bearing strength surface. It is apparent the portions of the state path lie outside
