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the bearing strength surface, so more than correct modelling of uplift is required for a
satisfactory shallow foundation model. A macro-element like that developed by Cremer
et al. (2001) or Paolucci (1997) is clearly what isrequired.
However,anotherapproachwasadoptedinonesetofRuaumokocalculationsandthecol-
umnbase-footingconnectionsweremodelledaspinned.Sincethentherewasnomoment
applied to the shallow foundations during the earthquake no demand was made on the
footing bearing strength which exceeded the available capacity. The state paths for foot-
ing 1 are shown in Figure 10.18. Now that there is no moment applied to the shallow
M = 0 section of bearing strength surface
0.3
0.2
0.1
Footing 1 state paths
0
-
0.1
-
0.2
-
0.3
0
0.2
0.4
0.6
0.8
1
V/V
uo
Fig. 10.18. State paths withinthe bearing strength surfacefor footing1 when there is a
moment freeconnection between the footing and column
20
Slope of allowable interstorey drift profile
Pinned column base
15
Fixed column base
10
5
0
-
0.2
-
0.1
0
0.1
0.2
Maximum lateral displacement profiles (m)
Fig. 10.19. Peak structural horizontal displacement envelopes for the three-storey
structureshown in Figure 10.14
